which
decodes a coded stream to generate quantized data; a
setting unit which sets a quantization parameter used
when the quantized data generated by the decoding unit is
10 inversely quantized for a coding unit in a layer lower
than a reference coding unit in a reference layer of the
coding unit. being a unit of coding process when image
data is coded; and an inverse quantization unit. which
inversely quantizes the quantized data generated by the
15 decoding unit by using the quantization parameter set by
the setting unit.
[0012]
The setting unit may set the quantization
parameter for a current coding unit by using a difference
20 quantization parameter indicating a difference value
between the quantization parameter set for the current
coding unit being a target of an. inverse quantization
process and the quantization parameter set for the coding
unit in the same layer as the current coding unit.
25 [0013]
The difference quantization parameter may be the
difference value between the quantization parameter set
for the current coding unit and the quantization
parameter set for the coding unit decoded before the
30 current coding unit in order of decoding process,
[0014]
4
SP300919W000
The difference quantization parameter may be the
difference value between the quantization parameter set
for the current coding unit and the quantization
parameter set for the coding unit decoded immediately
5 before the current coding unit in the order of decoding
process.
[0015]
The reference coding unit may be a largest coding
unit being the coding unit in a highest layer.
10 [0016]
The image processing apparatus may further
include: a receiving unit which receives the coded stream
and minimum coding unit size data indicating a minimum
size of the coding unit for which the difference
15 quantization parameter is set, and the .setting unit may
set the quantization parameter for the current coding
unit according to the minimum coding unit size data
received by the receiving unit,
[00171
20 The receiving unit may obtain the minimum coding
unit size data from a slice header of the coded stream.
[001-8]
When a size indicated by the minimum coding unit
size data is 16 pixels, the difference quantization
25 parameter for the coding unit of which size is smaller
than 16 pixels may be set. to 0e
[0019]
The setting unit may set the quantization
parameter for a current coding unit by using a difference
30 quantization parameter indicating a difference value
between the quantization parameter set for the current
SP300919WO00
coding unit being a target of a decoding process and the
quantization parameter set for a slice to which the
current coding unit belongs.
[0020]
5 The setting unit may set the quantization
parameter for the current coding unit by using the
difference quantization parameter indicating the
difference value between the quantization parameter set
for the current coding unit and the quantization
10 parameter set for the slice to which the current coding
unit belongs when the current coding unit is a first
coding unit in order of decoding process in a layer of
the reference coding unit.
[0021]
15 The reference coding unit may be a largest coding
unit being the coding unit in a highest layer.
[0022]
The image processing apparatus may further
include: a receiving unit which receives the coded stream
20 and minimum coding unit size data indicating a minimum
size of the coding unit for which the difference
quantization parameter is set, and the setting unit may
set the quantization parameter for the current coding
unit according to the minimum coding unit size data
25 received by the receiving unit,
[0023]
The receiving unit may obtain the minimum coding
unit size data from a slice header of the coded stream.
[0024]
30 The difference quantization parameter for the
coding unit of which size is smaller than 16 pixels may
6
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be set to 0 when a size indicated by the minimum coding
unit size data is 16 pixels.
[0025]
The setting unit may set the quantization
5 parameter set for the reference coding unit as the
quantization parameter set for the coding unit in a layer
lower than the reference coding unit when a value of the
difference quantization parameter is 0 for the coding
unit in the layer lower than the reference coding unit.
10 [0026]
The image processing apparatus may further
_includeo a receiving unit which receives difference
identification data for identifying whether the value of
the difference quantization parameter is 0 for the coding
15 unit in the layer lower than the reference coding unit,
and the setting unit may set the quantization parameter
set for the reference coding unit as the quantization
parameter set for the coding unit in the layer lower than
the reference coding unit by using the difference
20 identification data received by the receiving unit.
[0027]
An aspect of the present technology is an image
processing method, including: generating quantized data
by decoding a coded stream; setting a quantization
25 parameter used when the generated quantized data is
inversely quantized for a coding unit in a layer lower
than a reference coding unit in a reference layer of the
coding unit being a unit of coding process when image
data is coded; and inversely quantizing the generated
30 quantized data by using the set quantization parameter.
[002_8]
7
S9.300919W000
Another aspect of the present technology is an
image processing apparatus, including. a setting unit
which sets a quantization parameter used when. image data
is quantized for a. coding unit in a layer lower than a.
5 reference coding unit in a reference layer of the coding
unit being a unit of coding process when the image data
is coded; a quantization unit which generates quantized
data by quantizing the image data by using the
quantization parameter set by the setting unit; and a
10 coding unit which codes the quantized data generated by
the quantization unit to generate a coded stream.
[0029]
The setting unit may set a difference quantization
parameter indicating a difference value between the
15 quantization parameter set for a current coding unit
being a target of a coding process and the quantization
parameter set for the coding unit in the same layer as
the current coding unit, and the image processing
apparatus may further include, a transmitting unit which
20 transmits the difference quantization parameter set by
the setting unit and the coded stream generated by the
coding unite
[0030]
The setting unit may set, as the difference
25 quantization parameter, the difference value between the
quantization parameter set for the current coding unit
and the quantization parameter set for the coding unit
coded before the current coding unit in order of coding
process.
30 [0031]
The setting unit may set, as the difference
8
S2300919W000
quantization parameter, the difference value between the
quantization parameter set for the current coding unit
and the quantization parameter set for the coding unit
coded. immediately before the current coding unit in the
order of coding process,
[0032]
The reference coding unit may be a largest coding
unit being the coding unit in a highest layer,
[0033]
10 The setting unit may set minimum coding unit size
data indicating a minimum size of the coding unit for
which the difference quantization parameter is set, and
the transmitting unit may transmit the minimum coding
unit size data set by the setting unit.
15 [0034]
The transmitting unit may add, as a slice header,
the minimum coding unit size data set by the setting unit
to syntax of the coded stream generated by the coding
unit.
20 [0035]
The setting unit may set the difference
quantization parameter for the coding unit of which. size
is smaller than 16 pixels to 0 when a size indicated by
the minimum coding unit size data is set to 16 pixels.
25 [0036]
The setting unit may set a difference quantization
parameter indicating a difference value between the
quantization parameter set for a current coding unit
being a target of a coding process and the quantization
30 parameter set for a slice to which the current coding
unit belongs, and the image processing apparatus may
9
SP300919WO00
further includes a transmitting unit which transmits the
difference quantization parameter set by the setting unit
and the coded stream generated by the coding unite
[0037]
5 The setting unit may set, as the difference
quantization parameter, the difference value between the
quantization parameter set for the current coding unit
and the quantization parameter set for the slice to which
the current coding unit belongs when the current coding
10 unit is a first coding unit in order of coding process in
a layer of the reference coding unit.
[0038]
The reference coding unit may be a largest coding
unit being the coding unit in a highest layer.
15 [0039]
The setting unit may set minimum coding unit size
data indicating a minimum size of the coding unit for
which the difference quantization parameter is set, and
the transmitting unit may transmit the minimum coding
20 unit size data set by the setting unit.
[0040]
The transmitting unit may add, as a slice header,
the minimum coding unit size data set by the setting unit
to syntax of the coded stream generated by the coding
25 unit,
[0041]
The setting unit may set the difference
quantization parameter for the coding unit of which size
is smaller than 16 pixels to 0 when a size indicated by
30 the minimum coding unit size data is set to 16 pixels.
[0042]
10
SP300919W000
The setting unit may set the quantization
parameter set for the reference coding unit as the
quantization parameter set for the coding unit in the
layer lower than the reference coding unit when a value
5 of the difference quantization parameter is set to 0 for
the coding unit in the layer lower than the reference
coding unite
[0043]
The setting unit may set difference identification
10 data for identifying whether the value of the difference
quantization parameter is 0 for the coding unit in the
layer lower than the reference coding unit, and the image
processing apparatus may further include: a transmitting
unit which transmits the difference identification data
15 set by the setting unit and the coded stream generated by
the coding unit.
1.0044]
Another aspect of the present technology is an
image processing method, including: setting a
20 quantization parameter used when image data is quantized
for a. coding unit in a layer lower than a reference
coding unit in a reference layer of the coding unit being
a unit of coding process when the image data is coded;
generating quantized data by quantizing the image data by
25 using the set quantization. parameter; and generating a
coded. stream by coding the generated quantized data.
[0045]
In an aspect of the present technology, the coded
stream is decoded and the quantized data is generated,
30 the quantization parameter used when the generated
quantized data is inversely quantized is set for the
11
SP300919WO00
coding unit in the layer lower than the reference coding
unit in the reference layer of the coding unit being the
unit of coding process when the image data is coded, and
the generated quantized data is inversely quantized by
5 using the set quantization parameter.
[0046;]
In another aspect of the present technology, the
quantization parameter used when the image data is
quantized is set for the coding unit in the layer lower
10 than the reference coding unit in the reference layer of
the coding unit being the unit of coding process when the
image data is coded., the image data is quantized and the
quantized data is generated by using the set quantization
parameter, and the generated quantized data is coded and
15 the coded stream is generated.
EFFECTS OF THE INVENTION
[0047]
According to the present technology, the
20 quantization process or the inverse quantization process
may be performed more appropriately,
BRIEF DESCRIPTION OF DRAWINGS
[0048]
25 Fig. 1 is a block diagram illustrating a principal
configuration example of an. image coding apparatus to
which the present technology is applied.
Fig. 2 is a view illustrating an example of
correspondence relationship between a quantization
30 parameter for a luminance signal and a quantization
parameter for a chrominance signal.
12
;P300919W000
Fig, 3 is a view illustrating an example of a
macroblock.
Fig. 4 is a view illustrating another example of
the macrobloclce
5 Fig. 5 is a block diagram illustrating a detailed
configuration example of a quantization unit.
Fig. 6 is a view illustrating an example of an
image in a unit of macrobloclce
Fig. 7 is a flowchart illustrating an example of a
10 flow of a coding process.
Fig. 8 is a flowchart illustrating an example of a
flow of a quantization parameter calculation process,
Fig. 9 is a block diagram illustrating a principal
configuration example of an image decoding apparatus to
15 which the present technology is applied.
Fig, 10 is a block diagram illustrating a detailed
configuration example of an inverse quantization unit.
Fig. 11 is a flowchart illustrating an example of
a flow of a decoding process.
20 Fig. 12 is a flowchart illustrating an example of
a flow of an inverse quantization process.
Fig, 13 is a flowchart illustrating another
example of the flow of the quantization parameter
calculation process.
25 Fig. 14 is a flowchart illustrating another
example of the flow of the inverse quantization process.
Fig. 15 is a view illustrating a configuration
example of a coding unite
Fig. 16 is a view illustrating an example of the
30 quantization parameter assigned to each coding unit.
Fig. 17 is a view illustrating an example of
SP300919W000
syntax.
Fig. 10 is a block diagram illustrating another
configuration example of the image coding apparatus to
which the present technology is applied,
5 Fig. 19 is a block diagram illustrating a detailed
configuration example of a coding unit quantization unit
and a rate controller.
Fig, 20 is a flowchart illustrating still another
example of the flow of the quantization parameter
10 calculation process,
Fig. 21 is a block diagram illustrating another
configuration example of the image decoding apparatus to
which the present technology is applied.
Fig. 22 is a block diagram illustrating a detailed
15 configuration example of a coding unit inverse
quantization unite
Fig. 23 is a flowchart illustrating still another
example of the flow of the inverse quantization process.
Fig. 24 is a view comparing characteristics of
20 methods of calculating a quantization parameter dQP.
Fig. 25 is a view illustrating an example of the
quantization parameter assigned to each coding unit.
Fig. 26 is a view illustrating an example of the
syntax of a slice header.
25 Fig. 27 is a view illustrating an example of a
method of calculating activity,
Fig. 28 is a view illustrating a relationship
between the quantization parameter and a quantization
scale.
30 Fig. 29 is a block diagram illustrating still
another configuration example of the image coding
14
SP300919W000
apparatus to which the present technology is applied.
Fig. 30 is a block diagram illustrating a detailed
configuration example of the coding unit quantization
unit, the quantization unit, and the rate controller.
5 Fig. 31 is a flowchart illustrating another
example of the flow of the coding process.
Fig, 32 is a flowchart illustrating an example of
a flow of a quantization process.
Fig. 33 is a view illustrating an example of a
10 muii_i--view image coding system.
Fig. 34 is a view illustrating a principal
configuration example of the multi-view image coding
apparatus to which the present technology is applied.
Fig. 35 is a view illustrating a principal
15 configuration example of a multi-view image decoding
apparatus to which the present technology is applied.
Fig, 36 is a view illustrating an example of a
hierarchical image coding system.
Fig. 37 is a view illustrating a principal
20 configuration example of a hierarchical image coding
apparatus to which the present technology is applied.
Fig. 38 is a view illustrating a principal
configuration example of a hierarchical image decoding
apparatus to which the present technology is applied.
25 Fig. 39 is a block diagram illustrating a
principal configuration example of a computer to which
the present technology is applied,
Fig. 40 is a block diagram illustrating a
principal configuration example of a television apparatus
30 to which the present technology is applied.
Fig. 41 is a block diagram illustrating a
15
SP300919WO00
principal configuration example of a mobile terminal to
which the present technology is applied.
Fig. 42 is a block diagram illustrating a
principal configuration example of a
5 recording/reproducing apparatus to which the present
technology is applied.
Fig. 43 is a block diagram illustrating a
principal configuration example of an imaging apparatus
to which the present technology is applied.
10
MODE FOR CARRYING OUT THE INVENTION
[0049]
Modes for carrying out the present technology
(hereinafter, referred to as embodiments) are hereinafter
15 described. Note that the description is given in the
following order.
1D First Embodiment (Image Coding Apparatus)
2e Second Embodiment (image Decoding Apparatus)
3. Third Embodiment (Image Coding Apparatus/Image
20 Decoding Apparatus)
4. Fourth Embodiment (Image Coding Apparatus/Image
Decoding Apparatus)
5. Fifth Embodiment (Image Coding Apparatus)
6a Sixth Embodiment (Multi-View Image
25 Coding/Multi-View Image Decoding Apparatuses)
7. Seventh Embodiment (Hierarchical Image
Coding/Hierarchical Image Decoding Apparatuses)
8. Eighth Embodiment (Application)
[0050]
30 <1. First Embodiment>
[Image Coding Apparatus]
SP300919W000
Fig, 1 illustrates a configuration of one
embodiment of an image coding apparatus as an image
processing apparatus to which the present technology
applied.
[0051.]
An image coding apparatus 100 illustrated in Fig.
1 is a coding apparatus, which codes an image in a manner
similar to I-L 264/MPEC (Moving Picture Experts Group)-4
Part 10 (AVC (Advanced Video Coding)) (hereinafter,
10 referred to as H.264/AVC) system, for example. However,
the image coding apparatus 100 specifies a quantization
parameter for each sub macroblock.
[0052]
A macroblock is a partial area of the image, which
15 is a unit of process when the image is coded. The sub
macroblock is a small area obtained by dividing the
macroblock into a plurality of parts.
[0053]
In an example in Fig. 1, the image coding
20 apparatus 100 includes an A/D (Analog/Digital) converter
101, a screen reorder buffer 102, an arithmetic unit 103,
an. orthogonal transformation unit 104, a quantization
unit 105, a lossless coding unit 106, and an accumulation
buffer 107. The image coding apparatus 100 also includes
25 an. inverse quantization unit 108, an inverse orthogonal
transformation unit 109, an arithmetic unit 110, a
deblocking filter 111, a frame memory 112, a selector 113,
an intra prediction unit 114, a motion
prediction/compensation unit 115, a selector 116, and a
30 rate controller 117.
[0054]
17
S2300919W000
The image coding apparatus 100 further includes a
sub macroblock quantization unit; 121 and a sub macroblock.
inverse quantization unit 122,
[0055]
5 The A/D converter 101 A/D converts input image
data. and outputs the same to the screen reorder buffer
102 for storage.
[0056]
The screen reorder buffer 102 reorders the stored
10 image with frames in order of display into order of
frames for coding according to a GOP (Group of Picture)
structure, The screen reorder buffer 102 supplies the
image, in which order of the frames has been reordered,
to the arithmetic unit 103. The screen reorder buffer
15 102 supplies the image, in which order of the frames has
been reordered, also to the intra prediction unit 114 and
the motion prediction/compensation unit 115.
[0057]
The arithmetic unit 103 subtracts a predicted
20 image supplied from the infra prediction unit 114 or the
motion prediction/compensation unit 115 through the
selector 116 from the image read from the screen reorder
buffer 102 and outputs difference information to the
orthogonal transformation unit 104.
25 [0058]
For example, in a case of the image to which intra
coding is performed, the arithmetic unit. 103 subtracts,
from the image read from the screen reorder buffer 102,
the predicted image supplied from the intra prediction
30 unit 114. Also, in a case of the image to which inter
coding is performed, for example, the arithmetic unit 103
18
SP300919W000
subtracts, from the image read from the screen reorder
buffer 1.02, the predicted image supplied from the motion
prediction/compensation unit 115,
[0059]
5 The orthogonal transformation unit 104 performs an
orthogonal transform such as a discrete cosine transform
and a Karhunem-Loeve transform to the difference
information supplied from the arithmetic unit 103 and
supplies a transform coefficient to the quantization unit
10 105.
[0060]
The quantization unit 105 quantizes the transform
coefficient output from the orthogonal transformation
unit 104. The quantization unit 105 sets the
15 quantization parameter for each sub macr_obl.ock, which is
an area smaller than the macroblock, in cooperation with
the sub macroblock quantization unit 121 based on
information supplied from the rate controller 117 and
performs quantization, The quantization unit 105
20 supplies the quantized transform coefficient to the
lossless coding unit 106.
[0061]
The lossless coding unit 106 performs lossless
coding such as variable-length coding and arithmetic
25 coding to the quantized transform coefficient.
00062]
The lossless coding unit 106 obtains information
indicating intra prediction and the like from the intra
prediction unit 114 and obtains information indicating an
30 inter prediction mode, motion vector information and the
like from the motion prediction/compensation unit 1150
19
SP300919W000
Meanwhile , the information indicating the intra
prediction (intra prediction ) is hereinafter also
referred to as intra prediction mode information. Also,
information indicating an information mode i ndicating
5 inter prediction ( .nter prediction ) is hereinafter also
referred to as inter prediction mode information.
[0063]
The lossless coding unit 106 codes the quantized
transform coefficient and makes various pieces of
10 information such as a filter coefficient, the intra
prediction mode information, the inter prediction mode
information, and the quantization parameter a part of
header information of coded data (multiplexes) . The
lossless coding unit 106 supplies the coded data obtained
15 by the coding to the accumulation buffer 107 for
accumulation.
[0064]
For example, the lossless coding unit 106 performs
a lossless coding process such as the variable-length
20 coding or the arithmetic coding. The variable-length
coding includes CAVLC (Context-Adaptive Variable Length
Coding) defined by the He264/AVC system and the like.
The arithmetic coding includes CABAC (Context-Adaptive
Binary Arithmetic Coding) and the like.
25 [0065] -
The accumulation buffer 107 temporarily holds the
coded data supplied from the lossless coding unit 106 and
outputs the same as a coded image coded by the H.264/AVC
system to subsequent recording apparatus and transmission
30 channel not illustrated, for example, at a predetermined
timing.
20
SP300919W000
(00661
The transform coefficient quantized by the
quantizati on. unit 105 i s also supplied to the inverse
quantization unit 108. The inverse quantization. unit 108
5 inversely quantizes the quantized transform. coefficient
by a method corresponding to the quantization by the
quantization unit 105. The inverse quantization unit 108
performs inverse quantization by using the quantization
parameter for each sub macroblock set by the quantization
10 unit 105 i n cooperation with the sub macroblock inverse
quantization unit 122 . The inverse quantization unit 108
supplies an obtained transform coefficient to the inverse
orthogonal transformation unit 109.
[0067]
15 The inverse orthogonal transformation unit 109
inversely orthogonally transforms the supplied transform
coefficient using a method corresponding to an orthogonal
transform process by the orthogonal transformation unit
104, An output obtained by inverse orthogonal transform
20 (resto red difference information ) is supplied to the
ari_Ithmeti_c unit :CLOD
[0008]
The arithmetic unit 110 adds the predicted image
supplied from the intra prediction unit 114 or the motion
25 prediction/compensation unit 115 through the selector 116
to a result of the inverse orthogonal transform, that is,
the restored difference information supplied from the
inverse orthogonal transformation unit 109 to obtain a
locally decoded image (decoded image).
30 [0069]
For example, when the difference information
21
SP300919W000
corresponds to the image to which the intra coding is
performed, the arithmetic unit 110 adds the predicted
image supplied from the intra prediction unit 114 to the
difference information. Also, for example, when the
5 difference information corresponds to the image to which
the inter coding is performed, the arithmetic unit 1.10
adds the predicted image supplied from the motion
prediction/compensation unit 115 to the difference
information.
10 [0070]
An addition result is supplied to the deblocking
filter 111 or the frame memory 112.
[0071]
The deblocking filter Ill removes block distortion
15 of the decoded image by appropriately performing a
deblocking filter process and improves image quality by
appropriately performing a loop filter process by using a
Wiener filter, for example. The deblocking filter 111
classifies each pixel and performs an appropriate filter
20 process for each class. The deblocking filter 111
supplies a result of the filter process to the frame
memory 112.
[0072]
The frame memory 112 outputs an accumulated
25 reference image to the infra prediction unit 114 or the
motion prediction/compensation unit 115 through the
selector 113 at a predetermined timing.
[0073]
For example, in the case of the image to which the
30 intra coding is performed, the frame memory 112 supplies
the reference image to the intra prediction unit. 114
22
SP300919W000
through the selector 113, Also, for example, when the
inter coding is performed, the frame memory 112 supplies
the reference image to the motion prediction/compensation
unit 115 through the selector 113.
[0074]
When the reference image supplied from the frame
memory 112 is the image to which the intra coding is
performed, the selector 113 supplies the reference image
to the intra prediction unit 114. Also, when the
10 reforence image supplied from the frame memory 112 is the
image to which the inter coding is performed, the
selector 113 supplies the reference image to the motion
prediction/compensation unit 115.
[0075]
15 The infra prediction unit 114 performs the intra
prediction (infra prediction) to generate the predicted
image by using a pixel value in a screen. The intra
prediction unit 114 performs the intra prediction in a
plurality of modes (intra prediction modes).
20 [0076]
The intra prediction unit 114 generates the
predicted image in all of the intra prediction modes and
evaluates each predicted image to select an optimal modes
Upon selecting the optimal intra prediction mode, the
25 intr_a prediction unit 114 supplies the predicted image
generated in the optimal mode to the arithmetic unit 103
and the arithmetic unit 110 through the selector 116.
[0077]
Also, as described above, the intra prediction
30 unit 114 appropriately supplies, to the lossless coding
unit 106, the information such as the intra prediction
23
SP300919WO00
mode information indicating an adopted intra. prediction
mode.
[0078]
The motion. prediction/compensation unit 115
5 performs motion prediction by using the input image
supplied from the screen reorder buffer 102 and the
reference image supplied from the frame memory 112
through the selector 113, performs a motion compensation
process according to a detected motion vector and
10 generates the predicted image (inter prediction image
information) for the image to which the inter coding is
performed.
[0079]
The motion prediction/compensation unit 115
15 performs an inter prediction process in all of candidate
inter prediction modes to generate the predicted image.
The motion prediction/compensation unit 115 supplies the
generated predicted image to the arithmetic unit 103 and
the arithmetic unit 11.0 through the selector 116.
20 [0080]
lILlso, the motion prediction/compensation unit 115
supplies the inter prediction mode information indicating
an adopted inter prediction mode and motion vector
information indicating a calculated motion vector to the
25 lossless coding unit 106.
[0081]
In the case of the image to which the infra coding
is performed, the selector 116 supplies an output of the
infra prediction unit 114 to the arithmetic unit 103 and
30 the arithmetic unit 110, and in the case of the image to
which the inter coding is performed, the selector .116
24
S2300919W000
supplies an output of the motion prediction/compensation
unit 115 to the arithmetic unit 103 and the arithmetic
unit 110.
[0082]
5 The rate controller 117 controls a rate of
quantization operation of the quantization unit 105 such
that overflow or underflow does not occur based on a
compressed image accumulated in the accumulation buffer
107. The rate controller 117 supplies information
10 indicating complexity of the image to the quantization
unit 105 for each sub macroblock, which is the small area
obtained by dividing the macroblock into a plurality of
parts.
[0083]
15 For example, the rate controller 117 provides
activity, which is information indicating dispersion of
the pixel values, to the quantization unit 105 as the
information indicating the complexity of the image. It
goes without saying that the information indicating the
20 complexity of the image may be any information.
[0084]
The sub macroblock quantization unit 121 obtains
the information indicating the complexity of the image
for each sub macroblock from the quantization unit 105,
25 sets a quantization value (quantization step) for each
sub macroblock based on the information, and returns the
value to the quantization unit 105.
[0085]
The sub macroblock inverse quantization unit 122
30 obtains the quantization parameter from the inverse
quantization unit 108, obtains the quantization value for
25
SP300919W000
each sub macr_oblock by using the value of the parameter,
and returns the same to the inverse quantization unit 108,
[0086]
[Quantization of AVC]
5 Herein, the quantization defined by the AVC
(Advanced Video Coding) is described as an example of a
conventional quantization process.
[0087]
Although an integer transform matrix [H] defined
10 by the AVC does not satisfy a requirement: of an
orthogonal transform matrix represented by a following
equation (1), the orthogonal transform process is
performed by performing different quantization processes
to respective components after integer transform and
15 combining the integer transform and the quantization.
[0088]
[ H][H]T = I.1] ...(1)
[0089]
In the AVC, it is possible to define a
20 quantization parameter QP, which may have values from "0"
to "51", for each macroblock in order to perform the
quanLization..
[0090]
For example, suppose that A(QP) and B(QP) have
25 values, which satisfy a following equation (2),
regardless of the value of the QP.
[0091]
A(QP)*B(QP) = 2m + n ...(2)
[0092]
30 The orthogonal transform and the inverse
orthogonal transform in the AVC may be realized by
26
S2300919W000
operation represented by following equations (3) and (4)e
[00931
d = c*A(QP) /2m ... (3)
c' = d*B(QP)/2T1 (4)
[0094]
Meanwhile, c represents an orthogonal transform
coefficient before the quantization, d represents the
orthogonal transform coefficient after the quantization,
and c' represents the orthogonal transform coefficient
10 after_ the inverse quantization.
110095]
By performing such a process, it is possible to
realize the quantization and inverse quantization
processes not by division but only by shift operation in
15 the AVC.
[0096]
Meanwhile, values of A and B differ depending on
components
[00971
20 The quantization parameter QP is designed such
that the quantization process twice as coarse as the
original one is performed when the value :hereof
increments by 6 such as from 6 to 12, for example.
[0098]
25 Especially, deterioration in a chrominance signal
is easily noticeable at a lower bit rate, that is, with a
higher QP. Therefore, a default quantization parameter
QPc for the chrominance signal is defined with respect to
a quantization parameter QPy for a luminance signal as
30 indicated in a table in Fig. 2e
[00991
27
00919WO00
A user may control this relationship by setting
information about ChromaQPOffset included in image
compressed information.
[0100]
5 Also, in a. profile not lower than a High Profile,
it is possible to independently set the quantization
parameter for a Cb/Cr component by using Chrom.aQPOffset
and 22ndChromaOPOffsete
[0101]
10 [Quantization Parameter Calculation]
In the AVC coding system and coding systems
disclosed in Non-Patent Documents 1 and 2, a quantization
parameter MB QP for each macroblock is calculated in the
following manner.
15 [0102]
That is, QpBdOffsety is first calculated from
bit depth.luma minusS in a sequence parameter set a:
represented by a following equation (5)o
[0103]
20 QpBdOffsety = 6*bit_depth_luma_minus8 AN
[0102]
Next, an initial value of the quantization
parameter in each picture is specified by
pic init qp minus26 in a picture parameter set.
25 [0105]
Next, by slice qp delta defined in a slice layer,
a quantization parameter SliceQPy in the slice is
calculated as represented by a following equation (6),.
[0106]
30 SliceQPY = 26 -I- pic init qp minus26
slice qp delta ... (6 )
28
SP300919WO00
[0107]
Finally, by using rb_gp_delta in a macrobloclc
layer, the quantization parameter MB_QP for each
macroblock is calculated as represented by a following
5 equation (7)
[0;'08]
MB --OP = ((MB OPPr., + mb qp delta + 52 +
2*QpBdOffsety) % (52 + QpBdOfffsety)) QpBdOffsety ...(7)
[0109]
10 Herein, MB QPPrev represents the quantization
parameter for a previous macrobloclc.
[0110]
In the present technology, in addition to this,
information about submb qp delta is further included in a.
15 sub macroblock layer in image compression.
[0111]
By using this information, the quantization
parameter SubMB QP for each sub macroblock is calculated
as represented by a following equation (8),.
20 [0112]
SubMB QP = Cli_p(0,51,MB QP + submb qp_delta) ...( 8)
[0113]
Herein, Clip(min,max,value) represents a function
having a return value as represented by a following
25 equation (9).
[0114]
[Equation 1]
m , iif(vaiue rnax)
valued, Otherwise
..(9)
29
SP300919WO00
[0115]
That is, the quantization ;parameter_ Sub-MB-OP foi,
each sub macroblock. is calculated as represented by a
following equation (10). Herein, a minimum quantization
5 parameter defined in advance is minQP and a maximum
quantization parameter defined. in advance is maxQP.
[0116]
[Equation 2]
SU MB_ QP =-= Cl p(mm inQP, mwxQ , MB,-QP
-±sub mb__qp-,Sdeita)
10 ... (10)
[ 011-7 ]
Meanwhile, when there is no submb_gp_delta in the
image compressed information, a value thereof is set to
"0" and the quantiza.t..on parameter for the macroblock is
also applied to the sub macroblocko
[01-18]
[Quantization Uni.t]
Fig. 5 is a block diagram illustrating a detailed
configuration example of the quantization unit 105 in Fig.
20 1o As illustrated in Fig. 5, the quantization unit 105
includes a sub macroblock activity buffer 151, a
quantization parameter calculation unit 152, and a
quantization processor 153.
[0119]
25 The sub macroblock activity buffer 151 holds the
activity supplied from the rate controller 117. Although.
adaptive quantization based on the activity as defined in
a MPEG-2 Test Model is performed in the AVC coding system,
the rate controller 117 calculates the activity (also
30
SP300919W000
referred to as sub macrobloclc activity) for each sub
macroblock. A method of calculating the sub macrobloclc
activity is similar to that in a conventional case where
the activity is calculated for each macroblock.
[0120]
The sub macrobloclc activity buffer 151. holds the
sub macroblock activity supplied from the rate controller
117 and supplies the held sub macroblock activity to the
sub macroblock quantization unit 121 for each
10 predetermined amount (for example„ an amount of one
screen).
[0121]
The sub macroblock quantization unit 121
calculates the quantization value for each sub macrobloclc
15 by using the sub macroblock activity supplied from the
sub macroblock activity buffer 15], The quantization
value for each sub macroblock may be calculated by a
method similar to that in a case where the quantization
value for each macroblock is calculated from the activity
20 for each macroblock,
[0122]
After obtaining the quantization value for each
sub macroblock, the sub macroblock quantization unit 121
supplies the quantization value for each sub macroblock
25 to the quantization parameter calculation unit 1520
[0123]
The quantization parameter calculation unit 152
calculates various quantization parameters by using the
quantization value for each sub macroblock supplied from
30 the sub macroblock quantization unit 121,
[0124]
31
SP300919WO00
For example, the quantization parameter
calculation unit 152 calculates the quantization
parameters such as pic_init. qp minus26, sli_ce_gp_delta,
and mb qp delta, The quantization parameter calculation
5 unit 152 may obtain the quantization value for each
macroblock from the quantization value for each sub
macroblock. Therefore, the quantization parameter
calculation unit 152 calculates the various quantization
parameters to set as in a case of the conventional AVC
10 coding system.
1.0125]
The quantization parameter calculation unit 152,
further obtains the quantization parameter submb qp delta
indicating difference between the quantization parameter
15 MB QP for each macroblock and the quantization parameter
SubMB QP for each sub macroblock. it is required to
transmit the quantization parameter for each sub
macroblock to a decoding side. It becomes possible to
decrease a code amount of the quantization parameter for
20 each sub macroblock by obtaining a difference value in
this manner. So to speak, the quantization parameter
submb qp delta is a transmission format of the
quantization parameter SubMB OP. The quantization
parameter SubMB O_P for each sub macroblock may be
25 obtained by transforming the quantization value for each
sub macroblock. Similarly, the quantization parameter
MB QP for each macroblock is obtained by transforming the
quantization value for each macroblock. The quantization
parameter calculation unit 152 calculates submb qp delta
30 for each sub macroblock by using the above-described
equation (35), for example.
32
SP300919W000
[0126]
The quantization parameter calculation unit 152
supplies the quantization value for each sub macr_obloclc
to the quantization processor 153. Also, the
5 quantization parameter calculation unit 152 supplies
calculated various quantization parameters (specifically,
pic_i..nit_gp_minus26, slice gp_d.elta, mb_gp_delta. and the
like) to the lossless coding unit 106 and transmits the
same together with a coded stream obtained by coding the
10 imane. Meanwhile, as described above, when the value of
submb_gp delta is "0 transmission of submb_gp_delta is
omitted. That is, in this case, the quantization
parameter other than suburb qp delta is supplied to the
lossless coding unit 106,
15 [0127]
Further, the quantization parameter calculation
unit 152 ,upplies the quantization value for each sub
macroblock also to the inverse quantization unit 108,
[0128]
20 The quantization processor 153 quantizes the
orthogonal transform coefficient supplied from the
orthogonal transformation unit 104 by using the
quantization value for each sub macroblock,
[0129]
25 The quantization processor 153 supplies a
quantized orthogonal transform coefficient to the
lossless coding unit 106 and the inverse quantization
unit 108.
[0130]
30 Meanwhile, the inverse quantization unit 108
inversely quantizes the orthogonal transform coefficient
33
SP300919WO00
quantized by the above-described quantization unit 105 by
using the sub macroblock inverse quantization unit 122.
In an. image decoding apparatus corresponding to the image
coding apparatus 100 also, a process similar to the
5 inverse quantization process is performed, so that the
inverse quantization is described in detail when the
image decoding apparatus is described.
[01311
In the conventional case such as the AVC coding
10 system, only one quantization parameter may be set for
one macroblocke Therefore, in a case where a planar area
and an area including texture are mixed in one macroblock,
it is difficult to set the quantization parameter
appropriate for both of the areas.
15 [0132]
Especially, the larger the size of the macroblock
as an extended macroblock (extended partial area)
proposed in Non-Patent Document 2 and the like, the
higher the possibility that the images having different
20 characteristics are mixed in the area, so that it becomes
more difficult to perform the adaptive quantization
corresponding to the characteristics of each area.
[0133]
On the other hand, the image coding apparatus 100
25 may calculate an index indicating the complexity of the
image for each sub macroblock by the rate controller 117
and calculate the quantization value for each sub
macroblock by the sub macroblock quantization unit 121.
That is, the quantization processor 153 may perform the
30 quantization process by using the quantization value
appropriate for each sub macroblocke
34
S2300919WO00
[013 41
According to this, the image coding apparatus 100
may perform the quantization process more suitable for
contents of the image. Especially, also in a case where
5 the size of the macroblock is extended and both of the
flat area and the area including the texture are included
in a single macroblock, the image coding apparatus 100
may perform an adaptive quantization process suitable for
each area to inhibit subjective image quality of the
10 decoded image from deteriorating.
[0135]
For example, in an image 160 illustrated in Fig, 6,
a macroblock 161 includes only the flat area. Therefore,
even when the image coding apparatus 100 performs the
15 quantization process by using a single quantization.
parameter for such macroblock 161, there is no particular
problem in image quality,
[0136]
On the other hand, a macroblock 162 includes both
20 of the flat area and a texture area. In the quantization
process by using the single quantization parameter, it is
not possible to perform the adaptive quantization
appropriate for both of the flat area and the texture
area. Therefore, if the image coding apparatus 100
25 performs the quantization process by using the single
quantization parameter for such macroblock 161, the
subjective image quality of the decoded image might be
deteriorated.
[0137]
30 In such a case also, the image coding apparatus
100 may calculate the quantization value for each sub
35
SP300919WO00
macroblock as described above, so that it is possible to
perform a more appropriate quantization process to
inhibit the subjective image quality of the decoded. image
from de :er iorati_ng.
[01.38]
Also, when a total code amount for each picture is
likely to overflow in the accumulation buffer 107,
control by the quantization parameter is performed.
Therefore, at that time, by allowing the quantization
10 unit 105 to calculate the quantization value for each sub
macroblock and perform the quantization as described
above, the image coding apparatus 100 may control
measurement against the overflow in a smaller unit.
[0139]
15 Further, when the value of submb qp delta is "0",
transmission of suburb qp delta is omitted, so that it is
possible to inhibit unnecessary reduction in coding
efficiency. When the value of submb_cip_delta is "0", the
quantization parameter SubMB QP for each sub macroblock
20 and the quantization parameter MB OP for each macroblock
are equal to each other. Therefore, it is possible to
make the quantization parameter MB_QP for each macroblock
the quantization parameter SubMB QP for each sub
macroblock on the decoding side, so that the value of
25 submb qp delta ("0") is not required. Therefore, it is
possible to omit the transmission ofsubmb_gp_del.ta as
described above. It goes without saying that
suburb qp delta having the value of "0" may be
transmitted; however, it is possible to improve the
30 coding efficiency by omitting the transmission of
suburb qp de 1. tae
36
SP300919W000
[0140]
[Flow of Coding Process]
Next, a flow of each process executed by the
above-described image coding apparatus 100 is described.
5 First,, an example of a flow of a coding process is
described with reference to a flowchart, in Fig. 7.
[0141]
At step 5101, the A/U converter 101 A/U converts
the input image. At step S102, the screen reorder buffer
10 102 stores the A/D converted image and roorder_s pictures
in order of display into order for coding.
[0142]
At step 5103, the arithmetic unit 103 calculates
difference between the image reordered by the process at
15 step 5102 and the predicted image. The predicted image
is supplied to the arithmetic unit 103 through the
selector 116 from the motion prediction/compensation unit
115 in a case of the inter prediction and from the intra
prediction unit 114 in a case of the intra prediction,
20 respectively.
[0143]
A data amount of difference data is smaller than
that of original image data. Therefore, it is possible
to compress the data amount as compared to a case where
25 the image is directly coded.
[0144]
At step 5104, the orthogonal transformation unit
104 orthogonally transforms the difference information
generated by the process at step 5103. Specifically, the
30 orthogonal transform such as the discrete cosine
transform and the Karhunen-Loeve transform is performed
37
SP300919WOOD
and the transform coefficient is output.
[0145]
At step 5105, the quantization unit 1.05 arid the
sub macrobLock quantization unit 121 obtain the
5 guant.izati.on parameter, A flow of a quantization
parameter calculation process is described later in
detail.
[0146]
At step 5106, the quantization processor. 153 of
10 the quantization unit 105 quantizes the orthogonal
transform coefficient obtained by the process at step
5104 by using the quantization value for each sub
macroblock calculated by the process at step S105o
[0147]
15 The difference information quantized by the
process at step S106 is locally decoded in a following
manner. That is, at step S1.07, the inverse quantization
unit 108 inversely quantizes the quantized orthogonal
transform coefficient (also referred to as a quantized
20 coefficient) generated by the process at step S106 by
characteristics corresponding to characteristics of the
quantization unit 105. At step 5108, the inverse
orthogonal transformation unit 109 inversely orthogonally
transforms the orthogonal transform coefficient obtained
25 by the process at step S107 by characteristics
corresponding to characteristics of the orthogonal
transformation unit 104.
[0148]
At step 5109, the arithmetic unit 110 adds the
30 predicted image to the locally decoded difference
information to generate the locally decoded image (image
38
S9300919W000
corresponding to an. input to the arithmetic unit 103)4
At, step 5110, the dehloclci_ng filter 11.1 filters the image
generated by the process at step S109. According to this,
the block distortion is removed.
(.0149]
At step S111 , the frame memory 112 stores the
image from which the block distortion has been removed by
the process at step S110. Meanwhile , the image, which is
not subjected to the filter process by the deblocking
10 fil ter 111, also is supplied from the ari thmetic unit 110
to the frame memory 112 to be stored,
[0150]
At step 5112, the intra prediction unit 114
performs an infra prediction process in the intra
15 prediction mode. At step 5113, the motion
prediction/compensation unit 115 performs an inter motion
prediction process in which motion prediction and motion
compensation in the inter prediction mode are performed.
[0151]
20 At step S114, the selector 116 determines an
optimal prediction mode based on each cost function value
output from the infra prediction unit 114 and the motion
prediction/ compensation unit 115. That is, the selector
116 selects the predicted image generated by the intra
25 prediction unit 114 or the predicted image generated by
the motion. prediction/compensation unit 115.
[0152]
Also, selection information indicating the
selected predicted. image is supplied to the intra
30 prediction unit 114 or the motion prediction/compensation
unit 115 of which predicted image is selected. When the
39
SP300919W000
predicted image in the optimal infra prediction mode is
selected, the intra prediction unit 11.4 supplies
information indicating the optimal infra prediction mode
(that is, the intra prediction mode information) to the
5 lossless coding unit 106,
[0153]
When the predicted image of an optimal inter
prediction mode is selected, the motion
prediction/compensation unit 115 outputs information
10 indicating the optimal inter prediction mode and
information corresponding to the optimal inter prediction
mode as necessary to the lossless coding unit 106. The
information corresponding to the optimal inter prediction
mode includes the motion vector information, flag
15 information, reference frame information and the like.
1[0154]
At step S115, the lossless coding unit 106 codes
the transform coefficient quantized by the process at
step 5106. That is, the lossless coding such as the
20 variable-length coding and the arithmetic coding is
performed to a difference image (secondary difference
image in a case of inter).
[0155]
Meanwhile, the lossless coding unit 106 codes the
25 quantization parameter calculated at step S105 to add to
the coded data.
[0156]
Also, the lossless coding unit 106 codes the
information about the prediction mode of the predicted
30 image selected by the process at step 5114 to add to the
coded data obtained by coding the difference image. That
40
SP300919W000
is, the lossless coding unit 106 codes the infra
prediction mode information supplied from the intra
prediction unit 114 or the information corresponding to
the optimal inter prediction mode supplied from the
motion prediction/compensation unit. 115 and the like to
add to the coded data.
[0157]
At step S116, the accumulation buffer 107
accumulates the coded data output from the lossless
10 coding unit 1064 The coded data accumulated in the
accumulation buffer 107 is appropriately read to be
transmitted to the decoding side through the transmission
channel.
[0158]
15 At step S117, the rate controller 117 controls the
rate of the quantization operation of the quantization
unit 105 such that the overflow or the underflow does not
occur based on the compressed image accumulated in the
accumulation buffer 107 by the process at step S116,
20 [01.59]
When the process at step 5117 is finished, the
coding process is finished,
[0160]
[Flow of Quantization Parameter Calculation
25 Process]
Next, an example of the flow of the quantization
parameter calculation process executed at step 5105 in
Fig. 7 is described with reference to a flowchart in Fig.
8..
30 [0161]
When the quantization parameter calculation
41
SP300919W000
process is started, at step 5131, the sub macroblock:
activity buffer 151 obtains the sub macr.obloclc activity
supplied from the rate controller 117, The sub
macroblock activity buffer 151 holds the obtained sub
5 macroblock activity by the amount of one screen, for
example.
[0162]
At step 5132, the sub macroblock quantization unit
121 obtains the sub macroblock: activity by the amount of
10 one screen, for example, from the sub macroblock activity
buffer 151. Then, the sub macroblock quantization unit
121 calculates the quantization value for each sub
macroblock by using the obtained sub macroblock activity.
[0163]
15 At step 5133, the quantization parameter
calculation unit 152 ob.ain.s the quantization parameter
pic init qp minus26 by using the quantization value for
each sub macroblock calculated at step 57.32.
[0164]
20 At step 5134, the quantization parameter
calculation unit 152 obtains the quantization parameter
slice qp delta by using the quantization value for each
sub macroblock calculated at step 5132.
[0165]
25 At step 5135, the quantization parameter
calculation unit 152 obtains the quantization parameter
mb qp delta by using the quantization value for each sub
macroblock calculated at step 5132,
[0166]
30 At step 5136, the quantization parameter
calculation unit 152 obtains the quantization parameter
42
SP300919W000
submb qp delta by using the quantization value for each
sub m.acroblock calculated at step S132.
[016V]
After obtaining the various quantization
5 parameters as described above, the quantization unit 105
finishes the quantization parameter operation process,
returns the process to step S105 in Fig, 7, and allows
the process at step S106 and subsequent steps to be
executed.
10 [0163]
Since the coding process and. the quantization
parameter calculation process are performed in the abovedescribed.
manner, the image coding apparatus 100 may set
the quantization value for each sub macroblock and
perform the more appropriate quantization process.
[0169]
Also, since the qu tizai:ion parameter calculated
in this manner is transmitted to the image coding
apparatus, the image coding apparatus 100 may allow the
20 image decoding apparatus to obtain the quantization value
for each sub macroblock and perform the Inverse
quantization by using the same.
[0170]
<2. Second Embodiment>
25 [Image Decoding Apparatus]
Fig. 9 is a block diagram illustrating a principal
configuration example of an image decoding apparatus to
which the present technology is applied. An image
decoding apparatus 200 illustrated in Fig. 9 is a
30 decoding apparatus corresponding to an image coding
apparatus 1000
43
SP300919W000
[0171,]
Coded. data coded by the image coding apparatus 100
is transmitted to the image decoding apparatus 200
corresponding to the image coding apparatus 100 through a
predetermined transmission channel to be decoded.
[0172_1
As illustrated in Fig. 9, the image decoding
apparatus 200 includes an accumulation buffer 201, a
lossless decoding unit 202, an inverse quantization unit
10 203, an inverse orthogonal transformation unit 204, an
arithmetic unit 205, a deblocking filter 206, a screen
reorder buffer 207, and a D/A converter 208. The image
decoding apparatus 200 also includes a frame memory 209,
a selector 210, an intra prediction unit 211, a motion
15 prediction/compensation unit 212, and a selector 213.
[0173]
Further, the image decoding apparatus 200 includes
a sub macroblock inverse quantization unit 221.
[0174]
20 The accumulation buffer 201 accumulates the
transmitted coded data. The coded data is coded by the
image coding apparatus 100. The lossless decoding unit
202 decodes the coded data read from the accumulation
buffer 201 at a predetermined timing by a system
25 corresponding to a coding system of a lossless coding
unit 106 in Fig. V
[01751
The inverse quantization unit 203 operates in
cooperation with the sub macroblock inverse quantization
30 unit 221 to inversely quantize coefficient data obtained
by decoding by the lossless decoding unit 202 (quantized
44
SP300919W000
coefficient) by a system corresponding to a quantization
system of a quantization unit 105 in Fig. 1. That is,
the inverse quantization unit 203 inversely quantizes the
quantized coefficient by a method similar to that of an.
5 inverse quantization. unit 108 in Fig. 1 by using a
quantization parameter calculated for each sub macrobl_ocic
supplied from the image coding apparatus 100.
[0176]
The inverse quantization unit 203 supplies the
10 invorsely quantized coefficient data, thal, is, an
orthogonal transform coefficient to the inverse
orthogonal transformation unit 204. The inverse
orthogonal transformation unit 204 inversely orthogonally
transforms the orthogonal transform coefficient by a
15 system corresponding to an orthogonal transform system of
an orthogonal transformation unit 104 in Fig. 1 to obtain
decoded residual data corresponding to residual data
before orthogonal transform by the image coding apparatus
100a
20 [0177]
The decoded residual data obtained by inverse
orthogonal transform is supplied to the arithmetic unit
205. A predicted image is supplied from the infra
prediction unit 211 or the motion prediction/compensation
25 unit 212 through the selector 213 to the arithmetic unit
205.
[0178]
The arithmetic unit 205 adds the decoded residual
data to the predicted image to obtain decoded image data
30 corresponding to image data before subtraction of the
predicted image by an arithmetic unit 103 of the image
45
Sk300919WO00
coding apparatus 1.00. The arithmetic unit 205 supplies
the decoded image data to the deblocking filter 206.
[0179]
The deblocking filter 206 removes block distortion
from the supplied decoded image and thereafter supplies
the same to the screen reorder buffer 207.
[0180]
The screen reorder buffer 207 reorders an image.
That. is, frames reordered into order for coding by a
10 scr,aen reorder buffer 1.02 in Fig. 1 are reordered into
original order of display. The D/A converter 208 D/A
converts the image supplied from the screen reorder
buffer 207 and outputs the same to a display (not
illustrated) for display.
15 [0181]
An output of the debl.ocking filter 206 is further
supplied to the frame memory 209..
[0182]
The frame memory 209, the selector 210, the intra
20 prediction unit 211, the motion prediction/compensation
un:i_; 212, and the selector 213 correspond to a frame
memory 112, a selector 113, an intra prediction unit 114,
a motion prediction/compensation unit 115, and a selector
116 of the image coding apparatus 100, respectively.
25 [0183]
The selector 210 reads an image to which an inter
process is performed and a reference image from the frame
memory 209 to supply the images to the motion
prediction/compensation unit 212. Also, the selector 210
30 reads an image used for intra prediction from the frame
memory 209 to supply the image to the intra prediction
46
300919W000
unit 211.
[0184]
Information indicating an intro prediction mode
and the like obtained by decoding header information is
5 appropriately supplied from the lossless decoding unit
202 Lo the intra prediction unit 211. The intra
prediction unit 211 generates the predicted image from
the reference image obtained from the frame memory 209
based on this information and supplies the generated
10 predicted image to the selector 213.
[0185]
The motion prediction/compensation unit 212
obtains the information obtained by decoding the header
information (prediction mode information, motion vector
15 information, reference frame information, a flag, various
parameters and the like) from the lossless decoding unit
202.
[0186]
The motion prediction/compensation unit 212
20 generates the predicted image from. the reference image
obtained from the frame memory 209 based on the
information supplied from the lossless decoding unit 202
and supplies the generated predicted image to the
selector 213.
25 [0187]
The selector 213 selects the predicted image
generated by the motion prediction/compensation unit 212
or the intra prediction unit 211 and supplies the same to
the arithmetic unit 205.
30 [0188]
The sub macroblock inverse quantization unit 221
47
SP300919WO00
obtains the quantization parameter from the inverse
quantization unit 203 and obtains a quantization value
for each sub macroblock by using an equation (10) and
returns the same to the inverse quantization unit 203.
5 [0189]
[Inverse Quantization Unit]
Fig. 10 is a block diagram illustrating a detailed
configuration example of the inverse quantization unit
203.
10 [0190]
As illustrated in Fig. 1.0, the inverse
quantization unit 203 includes a. quantization parameter
buffer 251, an orthogonal transform coefficient buffer
252, and an inverse qua_nti_zation processor 253.
15 [0191_]
The parameter about quantization in each layer
such as a picture parameter set and a slice header of the
coded data supplied from the image coding apparatus 100
is decoded by the lossless decoding unit 202 to be
20 supplied to the quantization parameter buffer 251. The
qua.ntizati.on parameter buffer 251 appropriately holds the
quantization parameter, and supplies the quantization
parameter to the sub macroblock inverse quantization unit
221 at a predetermined timing.
25 [0192]
The sub macroblock inverse quantization unit 221
calculates a quantization parameter SubMt3_QP for each sub
macroblock as represented by equations (5) to (10), for
example, by using the quantization parameter supplied
30 from the quantization parameter buffer 251 and transforms
the same to the quantization value for each sub
48
SP300919W000
macrobl o< k to supply the quantizat i-on value to the
inverse quantization processor 2530
[0193]
Meanwhile, as described above in the first
5 embodiment, when a value of submb_gp delta is "0",
suburb qp delta is not transmitted. The sub macroblock
inverse quantization unit 221 applies a value of a
quantization parameter MB QP for each macroblock to the
quantization parameter SubMB 0P for each sub macroblock
10 when there is no suburb qp delta in the quantization
parameter supplied from the quantization parameter buffer
251,
[0194]
Also, the quantized orthogonal transform
15 coefficient obtained by decoding the coded data supplied
from the image coding apparatus 100 by the lossless
decoding unit 202 is supplied to the orthogonal transform
coefficient buffer 252, The orthogonal transform
coefficient buffer 252 appropriately holds the quantized
20 orthogonal transform coefficient and supplies the same to
the inverse quantization processor 253 at a predetermined
timing,
[0195]
The inverse quantization processor 253 inversely
25 quantizes the quantized orthogonal transform coefficient
supplied from the orthogonal transform coefficient buffer
252 by using the quantization value for each sub
macroblock supplied from the sub macroblock inverse
quantization unit 221. The inverse quantization
30 processor 253 supplies the orthogonal transform
coefficient obtained by inverse quantization to the
49
SP300919W000
inverse orthogonal transformation unit 204.
[0196]
As described above, the inverse quantization. unit
203 may perform an :inverse quantization process by using
5 the quantization value calculated for each sub macroblock.
According to this, the image decoding apparatus 200 may
perform the inverse quantization process more suitable
for contents of the image. Especially, even in a case
where the macroblock size is extended and both of a flat
10 area and an area including texture are included in a.
single macroblock, the image decoding apparatus 200 may
perform an adaptive inverse quantization process suitable
for each area to inhibit subjective image quality of the
decoded image from deteriorating.
15 [0197]
Meanwhile, the inverse quantization unit 108 of
the image coding apparatus 100 illustrated. in Fig , 3. also
has a configuration similar to that of the inverse
quantization unit 203 and performs a similar process,
20 However, the inverse quantization unit 108 obtains the
quantization parameter supplied from the quantization
unit 1.05 and the quantized orthogonal transform
coefficient and performs the inverse quantization.
[0198]
25 Also, the inverse quantization unit 108 provides
the quantization parameter to a sub macroblock inverse
quantization unit 122, which performs a process similar
to that of the sub macroblock inverse quantization unit
221, and allows the sub macroblock inverse quantization
30 unit 122 to generate the quantization value for each sub
macroblock,
50
SP300919W000
[0199]
[Flow of Decoding Process]
Next, a flow of each process executed by the
above-described image decoding apparatus 200 is described.
First, an example of a flow of a decoding process is
described with reference to a flowchart in Fig. 11.
[0200]
When the decoding process is started, the
accumulation buffer 201 accumulates the transmitted coded
10 dat.& at step S201. At step S202, the lossless decoding
unit 202 decodes the coded data supplied from the
accumulation buffer 201. That is, an I picture, a P
picture, and a B picture coded by the lossless coding
unit 106 in Fig. 1 are decoded,
15 [0201]
At that time, the motion vector information, the
reference frame information, the prediction mode
information (intr_a prediction mode or inter prediction
mode), and the information such as the flag and the
20 quantization parameter are also decoded.
[[0202]
When the prediction mode information is the intra
prediction mode information, the prediction mode
information is supplied to the intra prediction unit 211.
25 When the prediction mode information is the inter
prediction mode information, the motion vector
information corresponding to the prediction mode
information is supplied to the motion
prediction/compensation unit 212.
30 [0203]
At step 5203, the inverse quantization unit 203
51
00919W000
inversely quantizes the quantized orthogonal transform
coefficient obtained by decoding by the lossless decoding
unit 202, At step 5204, the inverse orthogonal
transformation unit 204 inversely orthogonally transforms
5 the orthogonal transform coefficient obtained by the
inverse quantization by the inverse quantization unit 203
by a method corresponding to the orthogonal
transformation unit 104 in Fig. 1. According to this,
difference information corresponding to an input of the
10 orthogonal transformation unit 104 in Fig. 1 (output of
the arithmetic unit 103) is decoded.
[0204]
At step 5205, the arithmetic unit 205 adds the
predicted image to the difference information obtained by
15 the process at step 5204. According to this, original
image data is decoded.
[0205]
At step 5206, the debloclcing filter 206
appropriately filters the decoded image obtained by the
20 process at step 5205. According to this, block
distortion is appropriately removed from the decoded
image.
[0206]
At step 5207 , the frame memory 209 stores the
25 filtered decoded image.
[0207]
At step 5208, the intra prediction unit 211 or the
motion prediction/compensation unit 212 performs a
prediction process of the image according to the
30 prediction mode information supplied from the lossless
decoding unit 202.
S 9 30091 9WO00
[0208]
That is, in a case where the intra prediction mode
information is supplied from the lossless decoding unit
202, the intra prediction unit 211 performs an infra
5 prediction process in the intra prediction mode. Also,
in a case where the inter prediction mode information is
supplied from the lossless decoding unit 202, the motion
prediction/compensation unit 212 performs a motion
prediction process in the inter prediction mode.
10 [0209]
At step 5209, the selector 213 selects the
predicted image. 'Chat is, the predicted image generated
by the intra prediction unit 211 or the predicted image
generated by the motion prediction/compensation unit 212
15 is supplied to the selector 213. The selector 213
selects the unit of which predicted image is supplied and
supplies the predicted image to the arithmetic unit 2050
The predicted image is added to the difference
information by the process at step 5205.
20 [0210]
At step S210, the screen reorder buffer 207
reorders the frames of the decoded image data, That is,
the frames of the decoded image data reordered for the
coding by the screen reorder buffer 102 of the image
25 coding apparatus 100 (Fig. 1) are reordered into the
original order of display.
(.021.1]
At step S211, the D/A converter 208 D/A converts
the decoded image data of which frames are reordered by
30 the screen reorder buffer 207. The decoded image data is
output to a display not illustrated and the image is
53
SP300919W000
displayed.
[0212]
[Inverse Quantization Process]
Next, an example of a flow of the inverse
quantization process is described with reference to a
flowchart in Fig. 12,
[0213]
When the inverse quantization process is started,
the quantization parameter buffer 251 obtains a
10 quaniizati_on parameter pic_init gp_minus25 supplied from
the lossless decoding unit 202 at step 5231.
[0214]
At step 5232, the quantization parameter buffer
251 obtains a quantization parameter slice_gp_delta
15 supplied from the lossless decoding unit 202.
[021_5]
At step 5233, the quantization parameter buffer
251 obtains the quantization parameter mb_gp_delta
supplied from the lossless decoding unit 202,
20 [0216]
At step 5234, the quantization parameter buffer
251 obtains a quantization parameter submb_gp_delta
supplied from the lossless decoding unit 202. However,
when there is no suburb qp delta, the process at step 5234
25 is omitted.
[0217]
At step 5235, the sub macrobloc]c inverse
quantization unit 221 calculates the quantization value
for each sub macrobloc]c by using various quantization
30 parameters obtained by the processes at steps 5231 to
S234. However, when suburb qp delta is not supplied from
54
SP30091.9W000
the image coding apparatus 100 and the process at step
5234 is omitted, the sub macroblock inverse quantization
unit 221 applies the quantization value for each
macroblock to the quantization value for each sub
macroblock,
[0216]
At step 5236, the inverse quantization processor
253 inversely quantizes the quantized orthogonal
transform coefficient held. by the orthogonal transform
10 coefficient buffer 252 by using the quantization value
for each sub macroblock calculated by the process at step
S235.
[0219]
When the process at step S236 is finished, the
15 inverse quantization unit 203 returns the process to step
S203 and allows the processes at step S204 and subsequent
steps to be executed.
[0220]
By performing the decoding process and the inverse
20 quantization process as described above, the image
decoding apparatus 200 may perform the inverse
quantization process by using the quantization value
calculated for each sub macroblock and perform the
inverse quantization process more suitable for the
25 contents of the image.
[0221]
<3, Third Embodiment>
[submb qp present flag]
Although it has been described above that
30 submb qp delta is appropriately transmitted as the
quantization parameter, it is also possible to further
55
SP300919W000
transmit a flag, which acknowledges presence of
suburb qp delta for each macroblock.
[0222]
In this case, a configuration of an image cod
5 apparatus 100 is similar to a configuration example
illustrated in Fig. 10 Also, a configuration of a
quantization unit 105 is similar to a configuration
g
example illustrated in Fig. 5. However , a quantization
parameter calculation unit 152 further calculates
10 submb qp present flag , which is flag information
indicating whether submb_gp_delta of which value is not
"0" is present , for each macrobloclc. When any
suburb qp delta. of sub macroblocks belonging to the
macrobloclc has the value not "0 ", suburb qp present flag
15 is set to " 1", for example . Also, when submb_gp_delt.a of
all the sub macroblocks belonging to the macroblock are
"0", subnta qp present flag i s set to "0", for example.
[0223]
It goes without saying that a value of
20 suburb qp pr_esent flag is arbitrary and any value may be
used as long as it is possible to identify a case where
any suburb qp delta has the value not "0" from a case
where suburb qp delta of all the sub macroblocks are "0"0
[0224]
25 When the quantization parameter calculation unit
152 sets the value in this manner, the quantization
parameter calculation unit 152 supplies
suburb qp present flag to the lossless coding unit 106 as
one of the quantization parameters. The lossless coding
30 unit 106 adds this submb qp present flag to a macroblock
header, for example, and codes the same. That is,
56
SP300919W000
submb qp presenLL flag is transmitted together with coded
data as well as another quantization parameter.
[022.5]
Therefore, a coding process in this case is
5 performed as in the case described above with reference
to the flowchart in Fig. 7. Also, an example of a flow
of a quantization parameter calculation process in this
case is described with reference to a flowchart in Fig.
13. In this case also, the quantization parameter
10 calculation process is performed in a manner basically
similar to that in the case illustrated with reference to
the flowchart in Fig. 8.
[0226]
That is, processes at steps S331 to S336 are
15 performed as the processes at steps S131 to S136 in Fig.
8. However, in this case, the quantization parameter
calculation unit 152 further calculates the quantization
parameter submb qp present flag at step S337,
[0227]
20 As described above, the quantization parameter
submb qp present flag is calculated to be transmitted.
[0220]
That is, subnCc) qp present flag is present in each
macroblock header of the data. Then , submb qp delta is
25 present in a sub macr_obloclc header of the macroblock in
which the value of submb qp present flag is "1" and
submb qp delta is not present i n. the sub macroblock
header of the macroblock in which the value of
submb qp present. flag is "0",
30 [0229]
Such coded data is transmitted from the image
57
SP300919W000
coding apparatus 100 to an image decoding apparatus 200.
[0230]
A configuration of the image decoding apparatus
200 in this case is similar to a. configuration example
5 illustrated in Fig, 9, Also, a configuration of an
inverse quantization unit 203 is similar to a
configuration example illustrated in Fig. 10. However, a
sub macroblock inverse quantization. unit 221 calculates a
quantization value for each macroblock for the macroblock
10 in which submb qp preseni flag is set to "0" without
waiting for supply of suburb qp delta and applies the
quantization value to the quantization value for each sub
macroblock
[0237.1
15 In other words, the sub macroblock inverse
quantization unit 221 obtains subrnb qp delta only when
submb qp present flag is ""1" and calculates the
quantization value for each sub mac.,rcblock.
[0232]
20 A decoding process in this case is performed. in a
manner_ similar to that described above with reference to
the flowchart in Fig. 11. Also, an example of a flow of
an inverse quantization process In this case is described
with reference to a flowchart in Fig. 14, In this case
25 also, the inverse quantization process is performed in a
manner basically similar to that in the case described
with reference to the flowchart in Fig. 12.
[0233]
That is, processes at steps 5431 to S433 are
30 performed as the processes at steps 5231 to 5233 in Fig..
12. However, in this case, the quantization parameter
58
SP300919W000
buffer 251 obtains the quantization parameter
submb gp_present_flag stored in the macroblock header at
step 5434.
[0234]
5 At step 5435, the sub macroblock inverse
quantization unit 221 determines whether the value of the
quantization parameter submb_gp_present_flag is "1"0
When the value of the quantization parameter
suburb qp present: flag is "1", the quantization parameter
TO buffer 251 obtains the quantization parameter
suburb qp delta at step 5436. At step 5437, the sub
macroblock inverse quantization unit 221 calculates the
quantization value for each sub macroblock, That is,
processes similar to those at steps S234 and S235 in Fig.
15 12 are performed.
[0235]
Also, when it is determined that the value of the
quantization parameter submb gp_present-_flag is "0" at
step 5435, the sub macroblock inverse quantization unit
20 221 calculates the quantization value for each macroblock
at step S43B and applies the same as the quantization
value for each sub macroblock,
[0236]
When the quantization value is calculated as in
25 the above-described manner, the inverse quantization
processor 253 performs inverse quantization by using the
quantization value at step S439.
[0237]
As described above, the image decoding apparatus
30 200 may more easily grasp the presence of the
quantization parameter submb_gp_delta and may more easily
59
32300919W000
calculate the quantization value without need for an
unnecessary process of searching suhmb_gp_delta, which is
not present, by transmitting submb_gp_present :f_lag
indicating the presence of the quantization parameter
5 submb qp delta for each. macroblock to use at the time of
the inverse quantization.
[0238]
Although the image coding apparatus, which codes
by the system equivalent to the AVC, and the image
10 decoding apparatus, which decodes by the system
equivalent to the AVC, are described above as an example
in the first to third embodiments, the scope of
application of the present technology is not limited
thereto and the present technology may be applied to
15 every image coding apparatus and image decoding apparatus,
which perform the coding process based on a block having
a hierarchical
[0239]
zcture as illustrated in Fig, 4.
Also, the above-described various quantization
20 parameters may be added to an arbitrary position of the
coded data or may be transmitted to a decoding side
separately from the coded data, for example. For example,
the lossless coding unit 106 may describe the information
in a bit stream as syntax. Also, the lossless coding
25 unit 106 may store the information in a predetermined
area as auxiliary information to transmit. For example,
the information may be stored in a parameter set (for
example, header and the like of sequence and picture)
such as SEI (Supplemental Enhancement Information).
30 [0240]
It is also possible for the lossless coding unit
60
SP300919W000
106 to transmit the information from the image coding
apparatus to the image decoding apparatus separately from
the coded data (as another file) In this case, it is
necessary to clarify correspondence relationship between
5 the information and the coded data (such that the
decoding side may grasp the relationship) but any method
may be used therefore For example, it is possible to
separately create table information indicating the
correspondence relationship or to embed link information
10 indicating corresponding data in each data.
[0241]
Meanwhile, it is also possible that the abovedescribed
quantization using the quantization value for
each sub macroblock (calculation of the quantization
15 parameter for each sub macroblock) is performed only for
an extended macroblock not smaller than 32x32,
110242]
For example, a rate controller 117 calculates
activity for each sub macrobloclc only when the current
20 macr_oblock is the extended macroblock and calculates the
activity for each macroblock when the current macroblock
is a conventional macroblock not larger than 16x16
defined in an existing coding standard such as the AVC,
[0243]
25 The sub macroblock quantization unit 121
calculates the quantization value for each sub macroblock
only for the extended macroblock and calculates the
quantization value for each macroblock for the
conventional macroblock not larger than 16x16, for
30 example.
[0244]
61
SP300919W000
The quantization parameter calculation unit 152
calculates the quantization parameter Submb_gp_delta only
for the extended macroblock and does not calculate the
quantization parameter submb_gp_delta for the
conventional macrobloclc not larger than 16x16, for
example
[0245]
The quantization processor 153 performs the
quantization by using the quantization value for each sub
10 macrobloclc only for the extended macroblock and performs
the quantization by using the quantization value for each
macroblock for the conventional macrobloclc not larger
than 16x16, for example.
[0246]
15 In the above-described manner, the image coding
apparatus 100 may perform the quantization by using the
quantization value for each sub macroblock only for the
extended macroblock having a large area in which an
effect of inhibiting deterioration in subjective image
20 quality of a decoded image may be sufficiently expected
and perform the quantization by using the quantization
value for each macroblock for the macrobloclc having a
conventional size in which the expectation for the effect
is relatively small. According to this, the image coding
25 apparatus 100 may inhibit increase in load caused by the
quantization using the quantization value for each sub
macroblock.
[0247]
In this case, it is of course possible for the
30 image decoding apparatus 200 to perform the inverse
quantization by using the quantization value for each sub
62
SP300919W000
macroblock only for the extended macroblock as the image
coding apparatus 100.
[0248]
For example, the sub macroblock inverse
5 quantization unit 221 calculates the quantization value
for each sub macroblock only for the extended macroblock
and calculates the quantization value for each macroblock
for the conventional macroblock not larger than 16x16
[0249]
10 Therefore, the inverse quantization. processor 253
performs the inverse quantization by using the
quantization value for each sub macroblock only for the
extended macroblock and performs the inverse quantization
by using the quantization value for each macroblock for
15 the conventional macroblock not larger than 16x16, for
example.
[0250]
In the above-described manner, the image decoding
apparatus 200 may perform the inverse quantization by
20 using the quantization value for each sub macroblock only
for the extended macroblock having the large area in
which the effect of inhibiting the deterioration in the
subjective image quality of the decoded image may be
sufficiently expected and perform the inverse
25 quantization by using the quantization value for each
macroblock for the macroblock having the conventional
size in which the expectation for the effect is
relatively small. According to this, the image decoding
apparatus 200 may inhibit the increase in the load caused
30 by the inverse quantization using the quantization value
for each sub macroblock
63
SP300919WO00
[02511
Meanwhile, when ,submbgp present flag is
transmitted as in the third embodiment, it may be
configured. to transmit the quantization parameter
5 suburb qp present flag only for the extended macroblock.
In other words, transmission of the quantization
parameter submb_gp_present_flag may be omitted for the
macroblock having the conventional size. CO course it
may be configured to transmit the quantization parameter
10 suburb qp present. flag having the value indicating that
there is no quantization parameter submb_gp_delta of
which value is other than "0" for the macrobloc]c having
the conventional size.
[0252]
15 <4, Fourth Embodiment>
[Summary]
Although it has been described above that the
quantization parameter is specified for each sub
macrobloc]c, a manner of assigning the quantization
20 parameter to the sub macroblock may be other than the
above-described one. For example, it is also possible to
define a quantization parameter SubMB_QP assigned to each
sub macroblock as represented by a following equation
(11) by using a quantization parameter submb_gp_delta for
25 each sub macroblock and a quantization parameter
previous qp for sub macroblock coded immediately before
the same.
[0253]
SubM]S_QP = C:lip(0,51,previous_gp + submb_gp_delta)
30 (11)
[0254]
64
SP300919WO00
[Coding Unit]
Such a method is to be described below; it is
hereinafter described by using a unit referred to as a
coding unit in place of the above-described ma.cr_oblock
and sub macroblock,
[0255]
For example, in a "Test Model Under Consideration"
(JCTVC°B205), an extended macroblocle described with
reference to Fig. 4 is defined by a concept referred to
10 as the coding unit.
[0256]
The coding unit is a division unit of an image
(one picture), which is a unit of process such as a
coding process of image data. That is, the coding unit
15 is a block (partial area) obtained by dividing the image
(one picture) into a plurality of parts. That is, the
coding unit corresponds to the above-described macr_oblock
and sub macroblocle.
[0257]
20 Fig. 15 is a view illustrating a configuration.
example of the coding unite As illustrated in Fig. 15,
an area of the coding unit may be further divided into a
plurality of parts and each area may be made the coding
unit of one layer lower. That is, the coding units may
25 be hierarchically configured (configured to have a tree
str_ucture). In addition, a size of the coding unit is
arbitrary and the coding units having different sizes may
be present in one picture.
[0258]
30 In an example in Fig. 15, the size of the coding
unit in a highest layer (depth = 0) is set to 128x128
65
SP30091 9W000
pixels, an area of 69x64 pixels obtained by dividing the
same in half vertically and horizontally (into four) is
made the coding unit in one layer lower (depth = 1), and
hierarchization of the coding units is similarly repeated
and an area of 8x8 pixels is made the coding unit in a
lowest layer (depth = n)
[02591
At that time, the coding unit in the highest layer
fer_red to as an LCU (Largest Coding Unit) and the
10 coding unit of the lowest layer is referred to as a SCU
(Smallest Coding Unit). That is, the LCU corresponds to
the macroblock and the coding unit in the lower layer
corresponds to the sub macrobloclc.
[0260]
15 Meanwhile, the size and a shape of the coding unit
of each layer and the number of layers are arbitrary.
That is, it is not required that the sizes and the shapes
of all the LCU and SCU be the same in the image (one
picture), the number of layers of the coding unit may be
20 different according to a position in the image, and a
manner of dividing the area is also arbitrary. That is,
the tree structure of the coding units may be an
arbitrary structure.
[0261.1
25 It goes without saying that a degree of freedom of
the hierarchical structure of the coding units may be
partially limited such that the manners of dividing the
area are the same but only the numbers of layers are
different, for example. For example, as illustrated in
30 Fig. 15, it is possible to configure such. that one area
(one picture or one coding unit) is divided in half
66
SP300919WO00
vertically and horizontally (that is, into four) in any
position and the sizes of the LCU and SCU in each
posii_ti..on are defined, thereby defining the hierarchical
structure of the coding units.
[0262]
The sizes of the LCU and SCU may be specified by a
sequence parameter set in image compressed information,
for example. It goes without saying that they may be
specified by another metadata and the like.
10 [0263]
[Assignment of Quantization Parameter]
In this embodiment, the quantization parameter
submb qp delta is assigned to each coding unit in place
of the macroblock. and the sub macroblock. However, in
15 this case, the quantization parameter submb_gp_delta is
not a difference value between a quantization parameter
MB QP for each macroblock and the quantization parameter
SubMB QP for each sub macroblock but the difference value
between the quantization parameter previous qp for a
20 previously coded coding uni-c and the quantization
parameter SubMB QP for the current coding unit.
[0264]
In other words, the quantization parameter
submb qp delta. indicating the difference value between
25 the quantization parameter previous_gp used for previous
coding and the quantization parameter SubMB_QP for the
current coding unit is assigned to each coding unit.
That is, the quantization parameter submb_gp_delta
satisfying the above-described equation (11) is assigned
30 to each coding unite
[02651
67
SP300919Wp00
Meanwhile, it is only required that, an ent.i re area
of the image be quantized, so that the quantization
parameter submb qp delta is actually assigned to a part
of the coding units such as only to the SCU, for example.
[02661
As in the above-described other embodiments, it is
possible to obtain the quantization parameter SubMB_QP
for the current coding unit by transforming a
quantization value obtained from activity for the coding
10 unit. Therefore, the quantization parameter
submb qp delta for each coding unit may be calculated by
using the equation (11).
[02671
Fig. 16 illustrates the configuration example of
15 the coding unit in one LCU and an example of the
quantization parameter assigned to each coding uni.L. A:
illustrated in Fig. 16, a difference value AQP between
the quantization parameter previous__rp used for the
previous coding and the quantization parameter SubMB_QP
20 for the current coding unit is assigned to each coding
unit. (CU) as the quantization parameter.
[0268]
More specifically, a quantization parameter AQP0
is assigned to an upper left coding unit 0 (Coding Unit
25 0) in the LCU. Also, a quantization parameter AQP10 is
assigned to an upper left coding unit 10 (Coding Unit 10)
out of four upper right coding units in the LCU. Further,
a quantization parameter AQPzl is assigned to an upper
right coding unit 11 (Coding Unit 11) out of the four
30 upper right coding units in the LCU. Also, a
quantization parameter AQP12 is assigned to a. lower left
68
>P300919W000
coding unit 12 (Coding Unit 1.2) out of the four upper
right coding unit.; in the LCU. Further, a quantization
parameter AQP13 is assigned to a lower right coding unit
13 (Coding Unit 13) out of the four upper right coding
units in the LOU.
[02691
A quantization parameter AQP20 is assigned to an
upper left coding unit 20 (Coding Unit 20) out of four
lower left coding units in the LOU, Further, a
10 quantization parameter AQP21 is assigned La an upper
right coding unit 21 (Coding Unit 21) out of the four
lower left coding units in the LCU. Also, a quantization
parameter AQP?2 is assigned to a lower left coding unit
22 (Coding Unit 22) out of the four lower left coding
15 units in the LOU, Further, a quantization parameter AQP23
is assigned to a lower right coding unit 23 (Coding Unit
23) out of the four lower left coding units in the LOU.
A quantization parameter AQP3 is assi,Oned to a lower
right coding unit 3 (Coding Unit 3) in the LCU.
20 [02701
The quantization parameter for the coding unit
processed immediately before the LCU is set to PrevQP,
Further, suppose that the upper left coding unit 0
(Coding Unit 0) in the LCU is the current coding unit
25 first processed in the LOU.
[0271]
A quantization parameter Cur_rentQP for the current
coding unit is calculated as represented by a following
equation (12)0
30 [0272]
CurrentQP = PrevQP + AQPo ... (12 )
69
SP300919WOOO
[0273;
Suppose that, the coding unit to be processed after
the coding unit. 0 is the upper left coding unit 10
(Coding Unit 10) out of the upper right four coding units
in the LCO illu strated in fig. I6.
[0274]
When the coding unit 10 becomes the processing
target, the quantization parameter CurrentQP of the
current coding unit is calculated as represented by
10 following equations (13) and (14).
[0275]
PrevQP = Cu_rrentQP ... (13 )
CurrentQP == PrevQP AQPn ,.(14)
[0276]
15 In this manner, by making the quantization
parameter assigned to each coding unit the difference
value between the quantization parameter for the
previously coded coding unit and the current quantization
parameter, it is not necessary to calculate the
20 quantization parameter for each macroblock, so that a
quantization process may be performed more easily.
[0277]
Meanwhile, when the difference value between the
quantization parameter for the already coded coding unit
25 and the current quantization parameter is calculated, it
is also possible to calculate the difference value from
the coding unit coded before the current coding unit
(coding unit coded before the previously coded coding
unit in the LCU). However, the difference value between
30 the quantization parameter for the previously coded
coding unit and the current quantization parameter is
70
sP300919WO00
preferable.
[0278]
That is, when the difference value between the
quantization parameter for the previously coded coding
5 unit and the current quantization parameter is calculated,
it is only required that only the quantization parameter
for the previously coded coding unit be stored in a
memory and the quantization parameter may be managed in a
FIFO (First In First Out) system. Therefore, when the
10 difference value of the quantization parameter is
calculated, the quantization parameter is easily managed
and a used amount of memory is small, so that there is an
advantage in mounting.
[0279]
15 Meanwhile, such a quantization. parameter
cu gp_d.el.ta for each coding unit is defined by syntax of
the coding unit as illustrated. in Fig. 17, for example,
to be transmitted to a decoding side. That is, the
quantization parameter cu qp delta for each coding unit.
20 corresponds to the above-described quantization parameter
sub qp delta,
[0200]
[Image Coding Apparatus]
Fig. 18 is a block diagram illustrating a
25 principal configuration example of an image coding
apparatus to which the present technology is applied. An
image coding apparatus 300 illustrated in Fig. 18 assigns
the quantization parameter cu qp delta to each coding
unit as described above.
30 [0281]
As illustrated in Fig, 18, the image coding
71
SP300919W000
apparatus 300 has a configuration basically similar to
that of an image coding apparatus 100 in Fig. 1. However,
the image coding apparatus 300 includes a coding unit
quantization unit 305 and a rate controller 317 in place
5 of a quantization unit 105, a rate controller 117, and a
sub macr,oblock quantization unit 121 of the image coding
apparatus 100. Also, the image coding apparatus 300
includes a coding unit inverse quantization unit 308 in
place of an inverse quantization unit 108 and a sub
10 macroblock inverse quantization unit 122 of the image
coding apparatus 100.
[0232]
The rate controller 317 controls a rate of
quantization operation of the coding unit quantization
15 unit 305 such. that overflow or underflow does not occur
based on a compressed image accumulated in an
accumulation buffer 107. Further, the rate controller
317 provides information indicating complexity of the
image for each coding unit to the coding unit
20 quantization unit 305. The coding unit quantization unit.
305 performs quantization for each coding unit by using
the activity, Also, the coding unit quantization unit.
305 calculates the quantization parameter for each coding
unit. The coding unit quantization unit 305 supplies an
25 orthogonal transform coefficient (coefficient data)
quantized for each coding unit and the calculated
quantization parameter for each coding unit to the
lossless coding unit 106 and codes the same to transmit.
Further, the coding unit quantization unit 305 also
30 provides the orthogonal transform coefficient
(coefficient data) quantized for each coding unit and the
72
SP300919W000
ulated. quantization paramet er for each coding unit
verse quantization unit 308.
[0283]
The coding e guan.iti_zation unit 308
5 performs inverse quantization for each coding unit by
using the quantization parameter for each coding unit
supplied from the coding unit quantization unit 305. The
coding unit inverse quantization unit 308 supplies the
orthogonal transform coefficient (coefficient data)
10 inversely quantized for each coding unit to the inverse
orthogonal transformation unit 109. The coding unit
inverse quantization unit 308 is to be described later in
detail in description of an image decoding apparatus.
[0284]
15 [Detailed Configuration about Quantization]
Fig. 19 is a block diagram illustrating a detailed
configuration example of the rate controller 317 and the
coding unit quantization unit 305
[0285]
20 As illustrated in Fig. 19, the rate controller 317
includes an activity calculation unit 321 and an activity
buffer 3220
[0286]
The activity calculation unit 321 obtains the
25 image being a target of the coding process (current
coding unit) from a screen reorder buffer 102 and
calculates the activity being information indicating
dispersion of pixel values as information indicating the
complexity of the image, That is, the activity
30 calculation unit 321 calculates the activity for each
coding unit. Meanwhile, it is only required that the
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SP300919WOOO
quantization process be performed fo r an entire image, so
that it is also possible that the activity is calculated
only for, a part of the coding units such as only for the
SCU, for example.
[0287]
The activity buffer 322 holds the activity for
each coding unit calculated by the activity calculation
unit 321 and provides the same to the quantization unit
105 at a predetermined timing. The activity buffer 322
10 holds the obtained activity for each coding unit by an
amount of one screen, for example.
[0288]
A method of calculating the activity is arbitrary
and may be a method similar to that of the above-
15 described MPEG2 Test Model, for example. Also, contents
of the information indicating the complexity of the image
also are arbitrary and may be the information other than
such activity.
[0289]
20 The coding unit quantization unit 305 includes a
coding unit quantization value calculation unit 331, a
picture quantization parameter calculation unit 332, a
slice quantization parameter calculation unit 333, a
coding unit quantization parameter calculation unit 334,
25 and a coding unit quantization unit 3350
[0290]
The coding unit quantization value calculation
unit 331 calculates the quantization value for each
coding unit based on the activity for each coding unit
30 (information indicating the complexity of the image for
each coding unit) supplied from the rate controller 317.
74
SP300919WOO0
The quantization value for each coding unit may be
calculated by a method similar to that in a case where
the quantization value for each LCU is calculated from
the activity for each LCU. Meanwhile, it is only
5 required that the quantization process be performed for
the entire image, so that it is also possible that the
quantization value for each coding unit is calculated
only for a part of the coding units. Hereinafter, it is
assumed that the quantization value for each coding unit
10 is calculated only for the SCU as an example.
[0291]
After obtaining the quantization value for each
coding unit, the coding unit quantization value
calculation unit 331 supplies the quantization value for
15 each coding unit to the picture quantization parameter
calculation unit 332,
[0292]
The picture quantization parameter calculation
unit 332 obtains a quantization parameter
20 pic i_nit qp mi.nus26 for each picture by using the
quantization value for each coding unite
[0293]
The slice quantization parameter calculation unit
333 obtains a quantization parameter slice_gp_delta for
25 each slice by using the quantization value for each
coding unite
[0294]
The coding unit quantization parameter calculation
unit 334 obtains a quantization parameter cu_gp_delta for
30 each coding unit by using the quantization parameter_
prevQP used for the previous coding.
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3P300919WO00
[0295]
The quantization parameters generated by the
picture quantization parameter calculation unit 332 to
the coding unit quantization parameter calculation unit.
334 are supplied to the lossless coding unit 106, coded,
and transmitted to the decoding side, and supplied also
to the coding unit inverse quantization unit 308.
1:0296]
The coding unit quantization unit 335 quantizes
10 the orthogonal transform coefficient of the current
coding unit by using the quantization value for each
coding unit.
[0297]
The coding unit quantization unit 335 supplies the
15 orthogonal transform coefficient quantized for each
coding unit to the lossless coding unit 106 and the
coding unit inverse quantization unit 308.
[0298]
[Flow of Coding Process]
20 The image coding apparatus 300 performs the coding
process basically as in the case of the image coding
apparatus 100 in Fig. 1 described with reference to Fig,
6a
[0299]
25 [Flow of Quantization Parameter Calculation
Process]
An example of a flow of a quantization parameter
calculation process executed in the coding process is
described with reference to a flowchart- in Fig. 20.
30 [0300]
When the quantization parameter calculation
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SP300919WOOO
process is strted, at step 3531, the. coding
quantization value calculation unit 331 obtains the
activity for each coding unit supplied. from the rate
controller 317.
[0301]
At step 3532, the coding unit quantization value
calculation unit 331 calculates the quantization value
for each coding unit by using the activity for each
coding unit..
10 [03021
At step ,S533, the picture quantization parameter
calculation unit 332 obtains the quantization parameter
pic init qp minus26 by using the quantization value for
each coding unit calculated at step 3532,
15 [0303]
At step 5534, the slice quantization parameter
calculation unit 333 obtains the quantization parameter
slice qp delta by using the quantization value for each
coding unit calculated at step 5532.
20 [03041
At step 3535, the coding unit quantization
parameter calculation unit 334 obtains the quantization
parameter cu qp delta for each coding unit (AQPo to AQP23
and the like in Fig. 16) by using the quantization
25 parameter prevQP used for the previous coding.
[0305]
After obtaining the various quantization
parameters in the above-described manner, the coding unit
quantization unit 305 finishes the quantization parameter
30 calculation process and performs subsequent processes of
the coding process.
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P300919W000
[0306]
Since the coding process and the quantization
parameter calculation process are performed in the abovedescribed
manner, the image coding apparatus 300 may set
the quantizati on value for each coding unit and perform a
more appropriate quantizati on process according to
contents of the image .
[0307]
Also, since the quantization parameter calculated
10 in this manner is transmitted to the image decoding
apparatus, the image coding apparatus 300 may allow the
image decoding apparatus to perform the inverse
quantization for each coding unit.
[0308]
15 Meanwhile, the coding unit inverse quantization
unit 308 included in the image coding apparatus 300
performs a process similar to that of the coding unit
inverse quantization unit included in the image decoding
apparatus corresponding to the image coding apparatus 300.
20 That is, the image coding apparatus 300 may also perform
the inverse quantization for each coding unit.
[0309]
[Image Decoding Apparatus]
Fig. 21 is a block diagram illustrating a
25 principal configuration example of the image decoding
apparatus to which the present technology is applied. An
image decoding apparatus 400 illustrated in Fig. 21,
which corresponds to the above-described image coding
apparatus 300, correctly decodes a coded. stream (coded
30 data) generated by the coding of the image data by the
image coding apparatus 300 to generate a decoded image.
78
S1='300919W000
[031 ,0]
As illustrated in Fig. 21, the image decoding
apparatus 400 has a configuration basically similar to
that of an image decoding apparatus 200 in Fig. 8 and
5 performs a similar process. However, the image decoding
apparatus 100 includes a coding unit inverse quantization
unit 403 in place of an inverse quantization unit 203 and
a sub macroblock inverse quantization unit 221 of the
image decoding apparatus 2000
10 [0371]
The coding unit inverse quantization unit 403
inversely quantizes the orthogonal transform coefficient
quantized for each coding unit by the image coding
apparatus 300 by using the quantization parameter and the
like for each coding unit supplied from the image coding
apparatus 300.
[0312]
Fig. 22 is a block diagram illustrating a.
principal configuration example of the coding unit
20 inverse quantization unit 403. As illustrated in Fig.. 22,
the coding unit inverse quantization unit. 403 includes a.
quantization parameter buffer 411, an orthogonal
transform coefficient buffer 412, a coding unit
quantization value calculation unit 413, and a coding
25 unit inverse quantization processor 414.
[031.3]
The quantization parameter in each layer such as a
picture parameter set and a slice header of the coded
data supplied from the image coding apparatus 300 is
30 decoded by a lossless decoding unit 202 to be supplied to
the quantization parameter buffer 411. The quantization
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SP30091 9W000
parameter buffer 411 appropriately holds the quantization
parameter and supplies the same to the coding unit
quantization value calculation unit 413 at a
predetermined timing.
[031_4]
The coding unit quantization value calculation
unit 47.3 calculates the quantization value for each
coding unit as represented by equations (36) to (39), for
example, by using the quantization parameter supplied
10 from the quantization parameter buffer 411 and supplies
the quantization value to the coding unit inverse
quantization processor 414.
[0315]
Also, the quantized orthogonal transform
15 coefficient obtained by decoding of the coded data
supplied from the image coding apparatus 300 by the
lossless decoding unit: 202 is supplied to the orthogonal
transform coefficient buffer 412. The orthogonal
transform coefficient buffer 412 appropriately holds the
20 quantized orthogonal transform coefficient to supply to
the coding unit inverse quantization processor 414 at a
predetermined timing.
[0316]
The coding unit inverse quantization processor 414
25 inversely quantizes the quantized orthogonal transform
coefficient supplied from the orthogonal transform
coefficient buffer 412 by using the quantization value
for each. coding unit supplied from the coding unit
quantization value calculation unit 413. The coding unit
30 inverse quantization processor 414 supplies the
orthogonal transform coefficient obtained by the inverse
30
SP300919WO00
quantization to an inverse orthogonal transformation unit.
204.
[0317]
As described above, the coding unit inverse
5 quantization unit 403 may perform an inverse quantization
process by using the quantization value calculated for
each coding unit. According to this, the image decoding
apparatus 400 may perform the inverse quantization
process more suitable for the contents of the image.
10 Espr'cially, even in a case where a size of the macroblock
is extended (the size of the LCU is large) and both of a
flat area and an area including texture are included in a
single LCU, the image decoding apparatus 400 may perform
an adaptive inverse quantization process suitable for
15 each area to inhibit subjective image quality of the
decoded image from deteriorating.
[0:318]
Meanwhile, the coding unit inv; rse quantization
unit 308 of the image coding apparatus 300 illustrated in
20 Fig. 18 also has a configuration similar to that of the
coding unit inverse quantization unit 403 and performs a
similar process. However, the coding unit inverse
quantization unit 308 obtains the quantization parameter
and the quantized orthogonal transform coefficient
25 supplied from the coding unit quantization unit 305 and
performs the inverse quantization,
[0319]
[Flow of Decoding Process]
The image decoding apparatus 400 performs a
30 decoding process in a manner basically similar to that in
a case of the image decoding apparatus 200 in Fig. 8
1
3P300919WO00
described with reference to the flowchart, in. Fig. 10
[0320]
[Flow of Inverse Quantization Process]
An example of a flow of the inverse quantization
process executed in the decoding process by the image
decoding apparatus 400 is described with reference to a
flowchart in Fig. 23.
110321]
When the inverse quantization process is started,
10 the quantization parameter buffer 411 obtains the
quantization parameter pic_init gp_minus26 supplied from
the lossless decoding unit 202 at step 56310
[0322]
At step 5632, the quantization parameter buffer
15 411 obtains the quantization parameter slice_gp_delta
supplied from the lossless decoding unit 2020
1.0323]
At step 5633, the quantiza.Lion parameter buffer
411 obtains the quantization parameter cu_gp_delta
20 supplied from the lossless decoding unit 202.
[0324]
At step 5634, the coding unit quantization value
calculation unit 413 calculates the quantization value
for each coding unit by using the various quantization
25 parameters obtained by the processes at steps 5631 to
5633 and the previously used quantization parameter
PrevQP.
[0325]
At step 5635, the coding unit inverse quantization
30 processor 414 inversely quantizes the quantized
orthogonal transform coefficient held by the orthogonal.
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SP300919W000
transform coefficient buffer 412 by using e
quantization value for each coding unit calculated by the
proces
[0326]
5 When the process at step 5635 is finished, the
coding unit inverse quantization unit 403 returns the
process to the decoding process and allows subsequent
processes to be executed.
[0327]
10 As described above, by performing the decoding
process and the inverse quantization process, the image
decoding apparatus 400 may perform the inverse
quantization process by using the quantization value
calculated for each coding unit and perform. the inverse
15 quantization process more suitable for the contents of
the image.
[0320]
As described above, in order t,u decrease a code
amount of the quantization parameter for each coding unit,
20 (sub macroblock), a difference value dQP between a
predetermined quantization parameter and the quantization
parameter SubM13 QP (quantization parameter
suburb qp delta) is obtained to be transmitted instead of
transmitting the quantization parameter. SubM13 QP itself.
25 Two methods represented by following equations (15) and
(16) have been described above as methods of calculating
the quantization parameter dQP,
(032_9]
dQP = CurrentQP - LCUQP ,..(15)
30 dQP = CurrentQP - PreviousQP ..(16)
8 3
SP300919W000
[0330]
In the equations (15) and (16), CurrentQP
represents the quantization parameter for the current
coding unit (CU)e Also, LCUQP represents the
5 quantization parameter for the LCU to which the curr
CU belongs (that is, the current LCU) Further,
t
PreviousQP represents the quantization parameter for the
CU processed immediately before the current CU.
[0331.]
10 That is, in a case of the equation (15), the
difference value between the quantization parameter for
the current LCU and the quantization parameter for the
current CU is transmitted. Also, in a case of the
equation (16), the difference value between the
15 quantization parameter of the previously processed CU and
the quantization parameter of the current CU is
transmitted
[0332]
The method of calculating such quantization
20 parameter dQP for transmission is arbitrary and may be
other than the above-described two examples,
[0333]
For example, it is also possible to transmit the
difference value between a quantization parameter SliceQP
25 for the slice to which the current CU belongs (that is,
the current slice) and the quantization parameter for the
current CU as represented by a following equation (17).
[0334]
30 [0335]
dQP = CurrentQP - SliceQP _(17)
The quantization parameter CurrentQP may be
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SP300919iWO00
obtained by transformation of the quantization value of
the current CU calculated by the coding unit quantization
value calculation unit 331 by the coding unit
quantization parameter calculation unit 334 in Fig. 19,
5 for example. Also , the quantization parameter SliceQP
may be obtained by the slice quantization parameter
calculation unit 333 in Fig. 19 using the quantization
parameter pic_mnit_gp minus26 obtained by the picture
quantization parameter calculation unit 332 and the
10 quanti zation parameter slice_gp_delta obtained by itself,
for example
[ 03361
Therefore, for example, the coding unit
quantization parameter calculation unit 334 in Fig. 19
15 may obtain the quantization parameter_ dQP by using the
values. The coding unit quantization parameter
calculation unit 334 supplies the quantization parameter
dQP to the lossless coding unit 106 to transmit to the
decoding side
20 [03371
The quantization parameter plc _init qp mi_nus26 and.
the quantization parameter sli_ce_gp_delta are defined in
the "Test Model Under Consideration" (JCTVC°B205), for
example, and may be set by a method similar to that of a
25 conventional coding system.
[03381
On the decoding side, the quantization parameter
for the CU may be obtained from the quantization
parameter dQP transmitted from a coding side.
30 [03391
For example, the coding unit quantization value
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S2300919WO00
calculation unit 413 obtains the quan ti zation parameter
SubMB QP for the CU as represented by a following
equation (18) from the quantization parameter dQP and
transforms the same to obtain the quantization value.
5 [0340]
SubMB Q,P -- Clip(minQP,maxQP,SliceQP +
suburb qp delta) ...(18)
[0341]
In the equation (18), minQP represents a minimum
10 quantization parameter defined in advance and maxQP
represents a maximum quantization parameter defined in
advance.
[0342]
In this manner, in a case where the quantization
15 parameter SliceQP is used for obtaining the quantization
parameter dQP also, the quantization and the inverse
quantization may be performed as the above-described two
methods. That is, not only the quantization and the
inverse quantization more suitable for the contents of
20 the image may be performed, but also the code amount of
the quantization parameter may be decreased.
[0343]
A. table in which characteristics of the processes
of the methods are compared to each other is illustrated
25 in Fig. 24, In the table illustrated in Fig. 24, a
method on the top (referred to as a first method) is a
method of obtaining the quantization parameter dQP by
using the quantization parameter for the LCU. A second
top method (referred to as a second method) is a method
30 of obtaining the quantization parameter dQP by using the
quantization parameter for the CU processed immediately
86
S'300919W000
before the current CU. A method on the bottom (referred
to a as third method) is at method of obtaining the
quantization parameter dQP by using the quantization
parameter for the current: slice.
[0.344]
In the table in Fig. 24, easiness of a pipeline
process and coding efficiency are compared to each other
as the characteristics of the methods. As indicated in
the table in Fig. 24, the pipeline process is easier in
10 the first method than in the second method. The pipe
line process is easier in the third method than in the
first method. Further, the coding efficiency is better
in the first method than in the third method. The coding
efficiency is better in the second method than in the
15 first method.
[0345]
That is, in general, the closer the area is to the
current area, the higher the c:orrelativlty with the
current area (such as the coding unit and the sub
20 macroblock)o Therefore, it is possible to further
improve the coding efficiency of the quantization
parameter dQP by obtaining the quantization parameter dQP
by using the area closer to the current area.
[0346]
25 However, in general, the farther the area is from
the current area, the earlier this is processed.
Therefore, time until the current area is processed
becomes longer. That is, allowed time for processing
delay and the like becomes longer. Therefore, when the
30 quantization parameter dQP is obtained by using the area
farther from the current area, delay is less likely to
87
300919WOO0
occur , which i s advantageous for the pipeline process.
1:0347]
As described above, the methods have different
characteristics, so that an appropriate method differs
5 depending on a condition having priority. Meanwhile, it
is also possible that each method may be selected. A
selecting method is arbitrary. For example, a user and
the like may determine in advance the method to be
applied. For example, it is also possible that any
10 method is adaptively selected according to an arbitrary
condition (for each arbitrary unit of process or when an
arbitrary event occurs, for example).
[0348]
When any method is adaptively selected, it is also
15 possible to generate flag information indicating the
selected method and transmit the flag information from
the coding side (quantization side) to the decoding side
(inverse quantization side), in this case, the decoding
side (inverse quantization side) may select. the same
20 method as that of the coding side (quantization side) by
referring to the flag information.
[0349]
Also, the method of calculating the quantization
parameter dQP is arbitrary and may be other than the
25 above-described method. The number of prepared
calculating methods is also arbitrary. Also, the value
may be variable. It is also possible to transmit
information defining the quantization parameter dQP from
the coding side (quantization side) to the decoding side
30 (inverse quantization side).
[0350]
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SP300919W000
The method of calculating the difference value of
the quantization parameter is illustrated in
consideration of the characteristics of the abovedescribed
methods. Fig. 25 illustrates an example of
5 configurations of the LCD and CU. The (number) indicates
order of coding (decoding) process of the coding units.
[0351]
In an LCU(0), the order of coding of the coding
units is as follows;
10 CU(0)
-*CU(10)-*CU(11)- CU(12)>CU(13)
-,CU(20) >CU(21)
->CU(30)-+CU(31)-*CU(32)>CU(33)
>CU(23)
15 >CU(3)
[0352]
In this case, the difference value of the
quantization parameter is as follows;
The coding unit CU(0) at the head of the LCU
20 transmits the difference value between the quantization
parameter SliceQP for the slice to which the CU(0)
belongs (that is, the current slice) and the quantization
parameter for the current CU(0) by using the equation
(17)
25 [0353]
dQP(CU(0)) = CurrentQP(CUO) -SliceQP
[0354
Next, the coding units CU(10) to CU(3) other than
the one at the head of the LCU transmit the difference
30 value between the quantization parameter (CurrentCU) for
the current CU and the previously coded CU (PrevisousCU)
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300919W000
by using the equation (16)
[0355]
dQP = CurrentQP(CUi) - PreviousQP(CU9.._1)
[0356]
5 That is, when it. is described with reference to
Fig. 25, the difference values of the quantization
parameter are as follows:
dQP(CU(70)) = CurrentQP(CU(10))
Pre vi souQP (CU (0) )
10 dQP(CO(11.)) = CurrentQP(CU(11.))
PrevisouQP(CU(10))
dQP(CU(12)) -= CurrentQP(CU(12))
Previ_souQP (CO (11.) )
dQP(CU(13) ) = CurrentQP(CU(13))
15 PrevisouOP(CU(12))
dQP(CU(20)) = CurrentQP(C(T (20))
Prev-i.souQ'2(CU(13))
dQP(C:U(21)) .= CurrentQP(CU(21))
PrevisouQP(CU(20))
20 dQP(CU(30)) == CurrentQP(CU(30)) --
Pre.vi.souOP(CU(21))
dQP(CU(31.)) = CurrentQP(CU(31.))
PrevisouQP(CU(30))
dQP(CU(32)) = CurrentQP(CU(32))
25 PrevisouQP(CU(31))
dQP(CU(33)) = CurrentQP(CU(33))
PrevisouQP(CU32))
dQP(CU(23)) = CurrentQP(CU(23))
PrevisouQ_P(CU33))
30 dQP(CU(3)) = CurrentQP(CU(3)) - PrevisouQP(CU23)
(035`7]
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SP300919W000
For, other LC'U(1) to LCU(N) also, the difference
values of the quantization parameter are similarly
calculated to be transmitted,
[03501
5 In this manner, it is possible to satisfy both of
the easiness of the pipeline process and the coding
efficiency by adopting advantage of the characteristics
of each. method (indicated by double circle in the
drawing) by calculating and transmitting the difference
10 valW of the quantization parameter.
[0359]
Meanwhile, in view of mounting, when closed
control is performed in the LUC, the coding unit CU(0) at
the head of the LCU may calculate the difference value of
the quantization parameter by using the equation (15)0
[03601
Meanwhile, the quantization parameter dQP
described above is not required to be set for all the
coding units, and this may be set only for the CU for
20 which it is desirable to set a value different, from a
reference quantization parameter such as LCUQP,
PreviousQP, and SliceQP.
[0361]
For this purpose, it is also possible to add
25 syntax MinCUForDQPCoded to the slice header (SliceHeader),
for example
[0362]
Fig. 26 is a view illustrating an example of the
syntax of the slice header. The number on a left end of
30 each row is a row number assigned for description.
[0363]
SP300919WO00
In an example in Fig. 26, MinCUl.orDQPCoded is set
in a 22nd line. This MinCUForDQPCoded specifies a
minimum CU size for which dQP is set. For example, even
when a minimum size of the CU is 8x8, if it is specified
5 That MinCUForDQPCoded = 16, the coding unit quantization
parameter calculation unit 334 of the image coding
apparatus 300 sets dQP only for the CU having a size not
smaller than 16x16 and does not set dQP for the CU having
the size of W. That is, in this case, dQP for the CO
10 having the size not smaller than 16x16 is transmitted.
Meanwhile, MinCUForDQPCoded may be set as a flag (for
example 0,4x4, 1:8x8, 2:16x16 and the like) to identify
(select) the minimum CU size for which dQP is set from
the CU size (4x4_, 8x8, 16x16, 32x32 and the like) set at
15 the time of coding (decoding) as a method of specifying
the minimum CU size for which dQP is set.
[0364]
For example, when one who makes an encoder only
wants to control with the CU having the size of 16x16, it
20 is required to transmit all dQP as 0 in the CU having the
size of 8x8 and this might deteriorate the coding
efficiency.
[0365]
Therefore, by setting such syntax MinCUForDQPCoded,
25 it is possible to omit the transmission of dQP for the CU
having the size of 8x8 in this case, thereby inhibiting
the coding efficiency from deteriorating,
[0366]
The coding unit quantization value calculation
30 unit 413 of the image decoding apparatus 400 grasps that
dQP for the CU having the size of 8x8 is not transmitted
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SP3009 WE)00
according to such syntax and calculates the quantization
value by using the reference quantization parameter such
as LCUQP, Prev:i.ousQP, and SliceQP.
[0367]
5 Meanwhile, Min.CUPorDQPCoded may be stored in oche
than the slice header. For example, this may be stored
in the picture parameter set (PicturePar_ameterSet)o It
is possible to support operation to change this value
after scene change, for example, by storing the same in
10 the slice header or the picture parameter set.
[0368]
However, when MinCUl^orDQPCoded is stored in the
slice header, it is possible to support a case where the
picture is multi-sliced and processed in parallel for
15 each slice also, which is more desirable.
[03691
<5. Fifth Embodi..ment>
[Summary]
Although it has been described above that the
20 quantization parameter for each sub macroblock (coding
unit smaller than the LCU) is transmitted from the image
coding apparatus to the image decoding apparatus, in this
case, it is required that the image decoding apparatus
also may obtain the quantization parameter for each sub
25 macroblock (coding unit smaller than the LCU) and perform
the quantization for each sub macroblock (coding unit
smaller than the LCU) by using the quantization parameter.
[0370]
Therefore, it may be configured such that the
30 image coding apparatus sets the quantization parameter
for each macrobloclc (LOU) and provides the quantization
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300919WOOO
parameter for each macrobl.ock (LCU) to the image decoding
apparatus while performing a quantization process for
each sub macroblock (coding unit smaller than the LOU)
[0371]
5 For example, when calculating activity for each
macroblock (LCU) by the above-described 'restModel 5, the
image coding apparatus calculates the activity for each.
block (coding unit) of 8x8, 16x16 and the like, smaller
than the macroblock (LCU) even when a size of the
10 macrobloclc (LOU) is 64x64, 128x128 and the like.
[0372]
Then, the image coding apparatus determines a
quantization parameter value for each 8xS block or 16x16
block based on the activity for each OR block or 1016
15 block based on a method of the TestModel5
[03'13]
However, the quantization parameter is set for
each macroblock (LCU).
[03741
20 For example, suppose that the size of the LCU
(macroblock) is 64x64 pixels as illustrated in Fig. 27.
When the image coding apparatus calculates the activity
for each 16x16 coding unit to calculate the quantization
parameter for the LOU, the activity for each coding unit
25 (block) becomes OP00 to QP33.
[0375]
In a case of the AVC, a quantization parameter QP
is designed such that the quantization process twice as
coarse as the original one is performed when a value
30 thereof increments by 6 such as from 6 to 12, for example,
as illustrated in Fig. 28.
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SP300919WO00
[03761
Deterioration in a chrominance sign
noticeable especially at a lower bit rate, that is, with
a higher QPo Therefore, a default quantization parameter
QPc for the chrominance signal is defined in advance with
respect to a quantization parameter QPy for a luminance
signal.
[0377]
A user may control this relationship by setting
10 information about ChromaQPOffset included in image
compressed information.
[0378]
On the other hand, in a case of this embodiment,
the image coding apparatus determines a quantization
15 parameter QPMB For the macroblock as represented by a
following equation (19) at a first step.
[03'79]
[Equation 3]
QPMB 1i"1lin QPii
ij 0, 3
20 [0380]
At a second step, the quantization process for
each block is performed by using values of the QP0B to
QP33. As a result, a position of a non-zero coefficient
in each block is stored in a memory.
25 [0381]
At a third step, the quantization process for each.
block is performed by using a value of the QPMB.
[0382]
At a fourth step, only a value in the position of
30 the coefficient being the nonzero coefficient also at
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the second step out of the non--zero obtained at the third
step is transmitted to lossless coding information as
coded information.
[0383]
5 By performing such a process, although only the
QPm is transmitted to the image compressed information
as the quantization parameter, it becomes possible to
realize adaptive quantization and improve subjective
image quality of the image compressed information being
10 an nitput by performing a pseudo process For each block
by using the values of the QPoo to QP33•.
1103841
[Image Coding Apparatus]
Fig. 29 is a block diagram illustrating a
15 principal configuration example of the image coding
apparatus to which the present technology is applied. As
illustrated in Fig. 29, an image coding apparatus 500 in
this case has a configuration basically similar to that
of an image coding apparatus 100 in Fig. I and
20 similar process.
[ 0:135)
However, the image coding apparatus 500 includes a
rate controller 317, a coding unit quantization unit 504,
and a quantization unit 505 in place of a quantization
25 unit 105, a rate controller 117, and a sub macroblock
quantization unit 121 of the image coding apparatus 100.
[03861
Although the image coding apparatus 100 in Fig. I
includes a sub macroblock inverse quantization unit 122
30 in addition to an inverse quantization unit 108, the
image coding apparatus 500 only includes the inverse
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quantization unit 108. That is, an inverse quantization
process is performed for each LCU (macroblock) as in
conventional AVC and the like. This also applies to the
image decoding apparatus corresponding to the image
coding apparatus 500,
[0387]
The coding unit quantization unit 504 performs the
quantization for each coding unit (for example, SCU) by
using the activity for each coding unit obtained by the
10 rate controller 317.
[0388]
The quantization unit 505 obtains the quantization
parameter for each LOU and performs the quantization for
each coding unit by using the same. Then, the
15 quantization unit 505 replaces the non-zero coefficient
out of quantized orthogonal transform coefficients of the
coding units obtained by the coding unit quantization
unit 504 with a result of the quantization process by the
quantization unit 505 (quantized orthogonal transform
20 coefficient) in the same position.
[0389]
A result of this replacement is supplied to the
lossless coding unit 106 and the inverse quantization
unit 108 as a result of the quantization. Also, the
25 quantization parameter for each LCU calculated by the
quantization unit 505 is supplied to the lossless coding
unit 106 and the inverse quantization unit 108.
[0390]
The inverse quantization unit 108 and an inverse
30 quantization unit of the image decoding apparatus (not
illustrated) perform inverse quantization by using the
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quantization parameter for each LCU as in the case of the
conventional AVC and the like.
[0391]
[Configurations of Rate Controller, Coding Unit
Quantization Uni and Quantization Unit]
Fig. 30 is a block diagram illustrating a detailed
configuration example of the rate controller, the coding
unit quantization unit, and the quantization unit in Fig.
290
10 [0392]
As illustrated in Fig. 30, the coding unit
quantization unit 504 includes a coding unit quantization
parameter determination unit 511, a coding unit
quantization processor 512, and a non-zero coefficient
15 position buffer 513,
[0393]
The coding unit quantization parameter
determination unit 511 determines a quantization
parameter CU QP for each coding unit. (for example, SCU)
20 in a layer lower than the LCU by using the activity for
each coding unit (for example, SCU) in the layer lower
than the LCU supplied from an activity buffer 322 of the
rate controller 317, The coding unit quantization
parameter determination unit 511 supplies the
25 quantization parameter CU QP for each coding unit to the
coding unit quantization processor 512 and an. LCU
quantization parameter determination unit 522 of the
quantization unit 505.
[0394]
30 The coding unit quantization processor 512
quantizes the orthogonal transform coefficient supplied
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from an orthogonal transform coefficient buffer 521 of
the quantization unit 505 for each coding unit (for
example, SCU) in the layer lower than the LOU by using
the quantization parameter CU_QP for each coding unit
5 supplied from the coding unit quantization parameter
determination unit 511. The coding unit quantization
processor 512 supplies the position of the coding unit in
which the value is not 0 (non-zero coefficient) out of
the quantized orthogonal transform coefficients of the
10 coding units obtained by the quantization to the non-zero
coefficient position buffer 513 and allow the same to
hold this position.
[0395]
The non zero coefficient position buffer 513
15 supplies the held position of the non-zero coefficient to
a coefficient replacing unit 524 of the quantization unit
505 at a predetermined timing.
[0396]
As illustrated in Fig. 30, the quantization unit
20 505 includes the orthogonal transform coefficient buffer
521, the LCU quantization parameter determination unit
522, an LOU quantization processor 523, and the
coefficient replacing unit 524.
[0397]
25 The orthogonal transform coefficient buffer 521
holds the orthogonal transform coefficient supplied from
an orthogonal transformation unit 104 and supplies the
held orthogonal transform coefficient to the coding unit
quantization processor 512 and the LCU quantization
30 processor 523 at a predetermined timing.
[0396]
SP300919WO00
The LCU quantization parameter determination unit.
522 determines a minimum value in the LCU of the
quantization parameters CU QP for each coding unit
supplied from the coding unit quantization parameter
5 determination unit 511 as a quantization parameter LCU QP
for each LCU as represented by the above-described
equation (19) The LCU quantization parameter
determination unit 522 supplies the quantization
parameter LCU_QP (minimum value of CU_QP in the current
10 LCU) for each LCU to the -LCU quantization processor 523.
[0399]
The LOU quantization processor 523 quantizes the
orthogonal transform coefficient supplied from the
orthogonal transform coefficient buffer 521 for each
15 coding unit (for example, SCU) in the layer lower than
the LOU by using the quantization parameter LOU QP for
each LCU supplied from the LCU quantization parameter
determination unit 522. The LOU quantization processor
523 supplies the quantized orthogonal transform.
20 coefficient for each coding unit obtained by the
quantization to the coefficient replacing unit 524.
[0400]
The coefficient replacing unit 524 replaces the
coefficient in the position different from the position
25 of the non-zero coefficient supplied from the non-zero
coefficient position buffer 513 out of the coefficients
of which value is not 0 (non-zero coefficient) of the
orthogonal transform coefficients quantized by the LCU
quantization processor 523 with 0.
30 [0401]
That is, the coefficient replacing unit 524 adopts
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a value of the result of the quantization as the
quantized orthogonal transform coefficient only for the
coding unit (in the layer lower than the LCU) in which
the obtained value of the result of the quantization is
5 not 0 in both of the quantization using the quantization
parameter CU0P determined for each coding unit in the
layer lower than the LCU and the quantization using the
quantization parameter LCU OP determined for each LCU.
On the other hand, the coefficient replacing unit 524
10 sets all the values of all of the quantized orthogonal
transform coefficients to 0 for other coding units (in
the layer lower than the LC
[0402]
The coefficient replacing unit 524 supplies the
15 quantized orthogonal transform coefficient of which value
is appropriately replaced in this manner to the lossless
coding unit 106 and the inverse quantization unit 108
together with the quantization parameter LCU QP
determined for each LCD.
20 [0403]
The lossless coding unit 106 codes supplied
coefficient data and quantization parameter to supply to
the image decoding apparatus (capable of decoding coded
data generated by the image coding apparatus 500)
25 corresponding to the image coding apparatus 500. The
image decoding apparatus performs the inverse
quantization by using the quantization parameter LCU QP
for each LCU supplied from the image coding apparatus 500
as in the case of the conventional AVC and the like..
30 [0404]
The inverse quantization unit 108 similarly
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SP300919WO00
inversely quantizes the coefficient data supplied from
the coefficient replacing unit 524 by using the
quantization parameter LCU OP for each LCU supplied from
the coefficient replacing unit 524.
5 [0405]
Meanwhile, the inverse quantization unit 108 has a
configuration basically similar to that of the inverse
quantization unit 203 described with reference to Fig. 10,
However, in the case of the inverse quantization

CLAIMS
1,. An image processing apparatus, comprising:
a decoding unit which decodes a coded stream to
5 generate quantized data;
a setting unit which sets a quantization parameter
used when the quantized data generated by the decoding
unit is inversely quantized for a coding unit in a layer
lower than a reference coding unit in a reference layer
10 of the coding unit being a unit of coding process when
image data is coded; and
an inverse quantization unit which inversely
quantizes the quantized data generated by the decoding
unit by using the quantization parameter set by the
15 setting unit..
2e The image processing apparatus according to claim
1, wherein
the setting unit sets the quantization parameter
20 for a current coding unit by using a difference
quantization parameter indicating a difference value
between the quantization parameter set for the current
coding unit being a target of an inverse quantization
process and the quantization parameter set for the coding
25 unit in the same layer as the current coding unit.
3. The image processing apparatus according to claim
2, wherein
the difference quantization parameter is the
30 difference value between the quantization parameter set
for the current coding unit and the quantization
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SP300919WO00
parameter set for the coding unit decoded before the
current coding unit in order of decoding process,
4e The image processing apparatus according to claim
5 3, wherein
the difference quantization parameter is the
difference value between the quantization parameter set
for the current coding unit and the quantization
parameter sei for the coding unit decoded immediately
10 before the current coding unit in the order of decoding
process.
5. The image processing apparatus according to claim
4, wherein
15 the reference coding unit is a largest coding unit
being the coding unit in a highest layer.
6e The image processing apparatus according to claim
5, further comprising:
20 a receiving unit which receives the coded stream
and ni.ni_mum coding unit size data indicating a minimum
size of the coding unit for which the difference
quantization parameter is set, wherein
the setting unit sets the quantization parameter
25 for the current coding unit according to the minimum
coding unit size data received by the receiving unite
7. The image processing apparatus according to claim
6, wherein
30 the receiving unit obtains the minimum coding unit
size data from a slice header of the coded stream.
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SP300919W000
8. The image processing apparatus according to claim
7, wherein
when a size indicated by the minimum coding unit.
5 size data is 16 pixels, the difference quantization
parameter for the coding unit of which size is smaller
than 16 pixels is set to 0.
9. The. image processing apparatus according to claim
10 1, wherein
the setting unit sets the quantization parameter
for a current coding unit by using a difference
quantization parameter indicating a difference value
between the quantization parameter set for the current
15 coding unit being a target of a decoding process and the
quantization parameter set for a slice to which the
current coding unit belongs.
10. The image processing apparatus according to claim
20 9, wherein
the setting unit sets the quantization parameter
for the current coding unit by using the difference
quantization parameter indicating the difference value
between the quantization parameter set for the current
25 coding unit and the quantization parameter set for the
slice to which the current coding unit belongs when the
current coding unit is a first coding unit in order of
decoding process in a layer of the reference coding unit.
30 11. The image processing apparatus according to claim
10, wherein
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the reference coding unit is a largest coding unit
being the coding unit in a highest layer.
12, The image processing apparatus according to claim
5 9, further comprising:
a receiving unit which receives the coded stream
and minimum coding unit size data indicating a minimum
size of the coding unit for which the difference
quantization parameter is set, wherein
10 the setting unit sets the quantization parameter
for the current coding unit according to the minimum
coding unit size data received by the receiving unite
13. The image processing apparatus according to claim
15 12, wherein
the receiving unit obtains the minimum coding unit
size data from a slice header of the coded stream.
14e The image processing apparatus according to claim
20 13, wherein
the difference quantization parameter for the
coding unit. of which size is smaller than 16 pixels is
set to 0 when a size indicated by the minimum coding unit
size data is 16 pixels.
25
iSo The image processing apparatus according to claim
1, wherein
the setting unit sets the quantization parameter
set for the reference coding unit as the quantization
30 parameter set for the coding unit in a layer lower than
the reference coding unit when a value of the difference
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SP300919W000
quantization parameter is 0 for the coding unit in the
layer lower than the reference coding unit.
16e The image processing apparatus according to claim
5 15, further comprising:
a receiving unit which receives difference
identification data for identifying whether the value of
the difference quantization parameter is 0 for the coding
unit in the layer lower than the reference coding unit,
10 wherein
the setting unit sets the quantization parameter
set for the reference coding unit as the quantization
parameter set for the coding unit in the layer lower than
the reference coding unit by using the difference
15 identification data received by the receiving unit.
17. An image processing method, comprising:
generating quantized data by decoding a coded
stream;
20 setting a quantization parameter used when the
generated quantized data is inversely quantized for a
coding unit in a layer lower than a reference coding unit
in a reference layer of the coding unit being a unit of
coding process when image data is coded; and
25 inversely quantizing the generated quantized data
by using the set quantization parameter.
18. An image processing apparatus, comprising:
a setting unit which sets a quantization parameter
30 used when image data is quantized for a coding unit in a
layer lower than a reference coding unit in a reference
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SP300919W000
layer of the coding unit being a unit of coding process
when the image data is coded;
a quantization unit which generates quantized data.
by quantizing the image data by using the quantization
parameter set by the setting unit; and
acoding unit which codes the quantized data
generated by the quantization unit to generate a coded
stream,
10 1.9, The image processing apparatus according to claim
18, wherein
the setting unit sets a difference quantization
parameter indicating a difference value between the
quantization parameter set for a current coding unit
1.5 being a target of a coding process and the quantization
parameter set. for the coding unit in the same layer as
the current- coding unit,
the image processing apparatus further comprising
a transmitting unit which transmits the difference
20 quantization parameter set by the setting unit and the
coded stream generated by the coding unit.
20. The image processing apparatus according to claim
19, wherein
25 the setting unit sets, as the difference
quantization parameter, the difference value between the
quantization parameter set for the current coding unit
and the quantization parameter set for the coding unit
coded before the current coding unit in order of coding
30 process.
141.
SP3009L9w000
21. The image processing apparatus according to claim
20, wherein
the setting unit sets, as the difference
quantization parameter, the difference value between the
quantization parameter set for the current coding unit
and the quantization parameter set for the coding unit
coded immediately before the current, coding unit in the
order of coding process.
10 22. The image processing apparatus according to claim
20, wherein
the reference coding unit is a largest coding unit
being the coding unit in a highest layer.
15 23. The image processing apparatus according to claim
22, wherein
the setting unit sets minimum coding unit size
data indicating a minimum size of the coding unit for
which the difference quantization parameter is set, and
20 the transmitting unit transmits the minimum coding
unit size data set by the setting unit.
24. The image processing apparatus according to claim
23, wherein
25 the transmitting unit adds, as a slice header, the
minimum coding unit size data set by the setting unit to
syntax of the coded stream generated by the coding unit.
25. The image processing apparatus according to claim
30 24, wherein
the setting unit sets the difference quantization
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SP300919WOOO
parameter for the coding unit of which size is smaller
than 16 pixels to 0 when a size indicated by the minimum
coding unit size data is set to 16 pixels.
5 26,. The image processing apparatus according to claim
18, wherein
the setting unit sets a difference quantization
parameter indicating a difference value between the
quantization parameter set for a current coding unit
10 being a target of a coding process and the quantization
parameter set for a slice to which the current coding
unit belongs,
the image processing apparatus further comprising:
a transmitting unit which transmits the difference
15 quantization parameter set by the setting unit and the
coded stream generated by the coding unit.
27e The image processing apparatus according to claim
26, wherein
20 the setting unit sets, as the difference
quantization parameter, the difference value between the
quantization parameter set for the current coding unit
and the quantization parameter set for the slice to which
the current coding unit belongs when the current coding
25 unit is a first coding unit in order of coding process in
a layer of the reference coding unit,
28, The image processing apparatus according to claim
27, wherein
30 the reference coding unit is a largest coding unit
being the coding unit in a highest layer.
SP300919W000
29, The image processing apparatus according to claim
28, wherein
the setting unit sets minimum coding unit size
5 data. indicating a minimum size of the coding unit for
which the difference quantization parameter is set, and.
the transmitting unit transmits the minimum coding
unit size data set by the setting unit.
10 30. The image processing apparatus according to claim
29, wherein
the transmitting unit adds, as a slice header, the
minimum coding unit size data set by the setting unit to
syntax of the coded stream generated by the coding unit.
15
31. The image processing apparatus according to claim
30, wherein
the setting unit sets the difference quantization
parameter for the coding unit of which size is smaller
20 than 16 pixels to 0 when a size indicated by the minimum
coding unit size data is set to 16 pixels.
32. The image processing apparatus according to claim
18, wherein
25 the setting unit sets the quantization parameter
set for the reference coding unit as the quantization
parameter set for the coding unit in the layer lower than
the reference coding unit when a value of the difference
quantization parameter is set to 0 for the coding unit in
30 the layer lower than the reference coding unite
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33, The image processing apparatus according to
32, wherein
claim
the setting unit sets difference identification
data for identifying whether the value of the difference
5 quantization parameter is 0 for the coding unit in the
layer lower than the reference coding unit,
the image processing apparatus further comprising.
a transmitting unit which transmits the difference
identification data set by the setting unit and the coded
10 stream generated by the coding unit,
34, An image processing method, comprising;
setting a quantization parameter used when image
data is quantized for a coding unit in a layer lower than
15 a reference coding unit in a reference layer of the
coding unit being a unit of coding process when the image
data is coded;
generating quantized data by quantizing the image
data by using the set quantization parameter; and
20 generating a coded stream by coding the generated
quantized data.