1. An image processing device comprising: I filter control means configured to instruct whether or not neighboring pixels of a I current block are to be filtered, responsive to an intra-prediction mode; I intra prediction means configured to subject said neighboring pixels to said filtering I processing as instructed by said filter control means, and performing intra prediction of said I current block; and encoding means configured to encode an image of said current block.

2. The image processing device comprising according to Claim 1, wherein said encoding means encode the mode of intra prediction of said current block; and wherein a filter setting means set a coefficient in accordance with the mode of intra prediction decoded by said decoding means, wherein said coefficient is configured of a filter coefficient and offset value.

3. The image processing device comprising according to Claim 2, wherein said filter coefficient is configured of three taps.

4. The image processing device according to Claim 2, wherein said filter coefficient has symmetry centered on a coefficient corresponding to zero-phase. I 5. An image processing method comprising the steps of: instructing whether the neighboring pixels of a current block are to be filtered, in response to an intra-prediction mode; subjecting said neighboring pixels to said filtering processing as instructed by said filter control means, and performing intra prediction of said current block; and - 2098- encoding an image of said current block.

6. The image processing method as claimed in claim 5 wherein said encoding encodes the mode of intra prediction of said current block; and a coefficient in accordance with the mode of intra prediction decoded by said decoding means is set, wherein said coefficient is configured of a filter coefficient and offset value.

7. The image processing method as claimed in claim 6 wherein the step of configuring filter coefficient is of three taps.

8. The image processing method as claimed in claim 6 wherein said filter coefficient has symmetry centered on a coefficient corresponding to zero-phase.

DESCRIPTION
Title of I vention: IMAGE PROCESSING DEVICE ? AND METHOD
Technical rield
[00011
The present invention relates to an image processing
device and pethod, and specifically relates to an image
processing device and method which enable prediction
efficiency to be improved.
BackgrounP Art
[0002]
In recent years, there have come into widespread use
devices wh.ich subject an image to compression encoding by
employing an encoding format for handling image information
as digital signals, and taking advantage of redundancy
peculiar to the image information with transmission and
storage of high effective information taken as an object at
that time to compress the image by orthogonal transform such
as discrete cosine transform or the like and motion
-
compensation. Examples of this encoding method include MPEG
(Moving Picture Experts Group) and so forth.
[0003]
In particular, MPEG2 (ISO/IEC 13818-2) is defined as a
general-purpose image encoding format, and is a standard
encompassing both of interlaced scanning images and
sequential-scanning images, and standard resolution images
and high definition images. For example, MPEG2 has widely
been employed now by broad range of applications for
professional usage and for consumer usage. By employing the
MPEG2 compression format, a code amount (bit rate) of 4
through 8 Mbps is allocated in the event of an interlaced
scanning image of standard resolution having 720 x 480
pixels, for example. Also, by employing the MPEG2
compression format, a code amount (bit rate) of 18 through
22 Mbps is allocated in the event of an interlaced scanning
image of high resolution having 1920 x 1088 pixels, for
example. Thus, a high compression rate and excellent image
quality can be realized.
[0004]
With MPEG2, high image quality encodipg adapted to
broadcasting usage is principally taken as a object, but a
lower code amount (bit rate) than the code amount of MPEG1,
i.e., an encoding format having a higher compression rate is
not handled. According to spread of personal digital
assistants, it has been expected that needs for such an
encoding format will be increased from now on, and in
response to this, standardization of the MPEG4 encoding
format has been performed. With regard to an image encoding
format, the specification thereof was confirmed as
international standard as ISO/IEC 14496-2 in December in
1998.
[0005]
Further, in recent years, standardization of a standard
serving as H.26L (ITU-T Q6/16 VCEG) has progressed with
image encoding, originally intended for television
conference usage. With H.26L1 it has been known that as
compared to a conventional encoding format such as MPEG2 or
MPEG4, though greater computation amount is requested for
encoding and decoding thereof, higher encoding efficiency is
realized. Also, currently, as part of activity of MPEG4,
standardization for also taking advantage of a function that
is not supported by H.26L with this H.26L taken as a base,
to realize higher encoding efficiency, has been performed as
Joint Model of Enhanced-Compression Video Coding. As a
schedule of standardization, H.264 and MPEG-4 Part10
(Advanced Video Coding, hereafter referred to as H.264/AVC)
become an international standard in March, 2003.
Further, as an extension thereof, standardization of
FRExt (Fidelity Range Extension) including a coding tool
necessary for business use such as RGB, 4:2:2, or 4:4:4,
8xEDCT and quantization matrix stipulated by MPEG-2 has been
completed in February, 2005. Thus, H.264/~vC has become a
encoding format capable of suitably expressing even film
noise included in movies, and has been employed for wide
ranging applications such as Blu-Ray Disc (registered
trademark) and so forth.
[0007]
However, nowadays, needs for further high-compression
encoding have been increased, such as intending to compress
an image having around 4000 x 2000 pixels, which is
quadruple of a high-vision image. Alternatively, needs for
further high-compression encoding have been increased, such
as intending to distribute a high-vision image within an
environment with limited transmission capacity like the
Internet. Therefore, with the above-mentioned VCEG (= Video
Coding Expert Group) under the control of ITU-TI studies
relating to improvement of encoding efficiency have
continuously been performed.
[0008]
Now, one factor that can be given why the H. 2 6'4 /AVC
format realizes high encoding efficiency as compared to the
conventional MPEG2 format or the like is employing an intra
prediction method.
[0009]
With the intra prediction method, the intra prediction
modes of nine kinds of 4 x 4 pixel and 8 x 8 pixel block
units, and four kinds of 16 x 16 pixel macro block units are
determined regarding luminance signals. The intra
prediction modes of four kinds of 8 x 8 pixel block units
are determined regarding color difference signals. The
intra prediction modes for color difference signals may be
set independently from the intra prediction modes for
luminance signals.
[OOlO]
There are particular patterns for each intra prediction
mode regarding how residual following such intra prediction
is manifested.
[OOll]
As a method to eliminate such redundancy and further
raise encoding efficiency, NPL 1 proposes the following
method.
[00121
That is to say, intra image encoding processing is
performed by normal H.264/AVC format using training signals
in offline processing beforehand, orthogonal transform such
as Karhunen-Lokve transform or the like is performed for
each intra prediction mode as to each block, and optimal
transform coefficients are calculated.
[0013]
Then, in the actual encoding processing, processing
using orthogonal t-ransform coefficients optimized for each
mode by the aforementioned Karhunen-Lohe transform are used
instead of the orthogonal transform stipu1ate.d by the
H . 2 64 /AVC format.
[0014]
Also, NPL 2 proposes a method of combining the
aforementioned intra prediction with inter prediction.
[0015]
That is to say, with NPL 2, difference information is
generated as to motion vector information obtained in inter
prediction not only for a current block but also for
neighboring pixel values around the current block.
Performing intra prediction between the difference
information relating to the current block, and the
difference information relating to neighboring pixels,
generated in this way, generates second order difference
information. The generated second order difference
information is then subjected to orthogonal transform and
quantization, and output downstream along with a compressed
image.
Thus, encoding efficiency is further improved.
Also, as described above, the macro block size is 16 x
16 pixels with the H.264/AVC format. However, a macro block
size of 16 x 16 pixels is not optimal for large image frames
such as UHD (Ultra High Definition; 4000 x 2000 pixels)
which will be handled by next-generation encoding methods.
[0018]
Accordingly, NPL 3 and so forth propose enlarging the
macro block size to a size of 32 x 32 pixels, for example.
Citation List
Non Patent Literature
NPL 1: "Improved Intra Coding", VCEG-AF15, ITUTelecommunications
Standardization Sector STUDY GROUP
Question 6 Video coding Experts Group (VCEG), 20-21 April
2007
NPL 2: "Second Order Prediction (SOP) in P Slice",
Sijia Chen, Jinpeng Wang, Shangwen Li and, Lu Yu, VCEG-AD09,
ITU-Telecommunications Standardization Sector STUDY GROUP
Question 6 Video coding Experts Group(VCEG), 16-18 July 2008
NPL 3: "Video Coding Using Extended Block Sizes", VCEGAD09,
ITU-~elecommunications Standardization Sector STUDY
GROUP Question 16 - Contribution 123, Jan 2009
Summary of Invention
Technical Problem
Now, with the H.264/AVC format, low-pass filter
processing of pixel values of neighboring pixels is
performed before performing intra prediction in increments
of blocks of 8 x 8 pixels describe above. Thus, noise
included in the neighboring pixels is removed, and
correlation is raised, so higher encoding efficiency can be
realized.
[0021]
However, regardless the fact that the degree of
included noise differs according to the input images,
quantization parameter values, intra prediction modes, and
so forth, the low-pass filter for removing the noise has
been fixed with the H.264/AVC format. That is to say, this
low-pass filter has not been optimal in accordance with
input images, quantization parameter values, intra
prediction modes, and so forth.
[0022]
Also, with the H.264/~vC format, the noise removal of
pixel values of neighboring pixels described above is only
performed with the intra prediction mode in increments of
blocks of 8 x 8 pixels, and has not been applied for other
modes. .
[0023]
The present invention has been made in light of this
situation, and realizes noise removal in accordance with
images and bit rates, thereby improving prediction
efficiency.
Solution to Problem
[0024]
An image processing device according to a first aspect
- 9 -
Slop1269
of the present invention includes: decoding means configured
to decode an image of a current block which is to be the
object of decoding processing; filter setting means
configured to set, in accordance with the current block, a
coefficient to be used for filtering processing to which
neighboring pixels of the current block are to be subjected
to, used for intra prediction of the current block, in
accordance with an encoding parameter; and intra prediction
means configured to subject the neighboring pixels to the
filtering processing using the coefficient set by the filter
setting means, and performing intra prediction of the
current block.
[00251
The encoding parameter may include a mode of intra
prediction of the current block, or a quantization parameter
of the current block; the decoding means may decode the mode
of intra prediction of the current block or the quantization
parameter of the current block; and the filter setting means
may set the coefficient in accordance with the mode of intra
prediction decoded by the decoding means, or the
quantization parameter decoded by the decoding means.
[0026]
The image processing device may further include: filter
coefficient storage means configured to store the
coefficient; wherein the coefficient is calculated so as to
obtain, with a learning image, the smallest residual between
a learning block which is the object of encoding processing,
and a prediction image obtained by performing intra
prediction for the learning block corresponding to a mode of
intra prediction of the learning block or a quantization
parameter of the learning block, and is stored in the filter
coefficient storage means; and wherein the filter setting
-
means set, as the coefficient, that from the coefficients
stored in the filter coefficient storage means which
corresponds to the mode o'f intra prediction of the current
block, or the quantization parameter of the current block.
[0027]
The filter coefficient storage means may hold the
coefficient as an n-bit (wherein n is an integer) value in
accordance with a register length of a processor.
[0028]
The decoding means may decode the coefficient, which
has been calculated at an encoding side using the
neighboring pixels prior to being subjected to the filtering
processing such that the residual as to a prediction image
obtained by intra prediction being performed regarding the
current block is smallest, and which has been set
corresponding to the current block, and to the mode of intra
prediction of the current block or the quantization
parameter of the current block; and the filter setting means
may set, as the coefficient, that from the coefficients
decoded by the decoding means which corresponds to the mode
of intra prediction of the current block, or the
quantization parameter of the current block.
[0029]
The coefficient may be configured of a filter
coefficient and offset value.
[0030]
The filter coefficient may be configured of three taps.
[0031]
The filter coefficient may have symmetry centered on a
coefficient corresponding to zero-phase.
COO321
The decoding means may decode the mode of intra
prediction of the current block; and the filter setting
means may take, of modes of intra prediction, a vertical
mode or horizontal mode as a first class, and other modes as
a second class, and, in the event that the mode of intra
prediction of the current block belongs to the first class,
set the coefficient corresponding to the first class, and in
the event that the mode of intra prediction of the current
block which has been decoded belongs to the second class,
set the coefficient corresponding to the second class.
[0033]
The image processing device may further include:
receiving means configured to receive flag information
indicating whether or not to perform the filtering
processing as to the neighboring pixels; wherein the filter
setting means set whether or not to perform the filtering
processing as to the neighboring pixels, based on flag
information received by the receiving means.
[ 0 0 3 4 ]
The receiving means may receive the flag information in
increments of macro blocks; and the filter setting means may
set whether or not to perform the filter processing as to
the neighboring pixels, in increments of macro blocks, based
on flag information received by the receiving means.
[ 0 0 3 5 ]
The receiving means may receive the flag information in
increments of blocks; and the filter setting means may set
whether or not to perform the filter processing as to the
neighboring pixels, in increments of blocks, based on flag
information received by the receiving means.
' An image processing method according to the first
aspect of the present invention includes the steps of: an
image processing device performing decoding of an image of a
current block which is to be the object of decoding
processing; setting of, in accordance with the current block,
a coefficient to be used for filtering processing to which
neighboring pixels of the current block are to be subjected
to, used for intra prediction of the current block, in
accordance with an encoding parameter; and subjecting the
neighboring pixels to the filtering processing using the
coefficient that has been set, and performing intra
prediction of the current block.
[DO371
An image processing device according to a second aspect
of the present invention includes: filter setting means
configured to set a coefficient to be used for filtering
processing to which neighboring pixels of a current block
which is to be the object of decoding processing are to be
subjected to, used for intra prediction of the current block,
in accordance with an encoding parameter; intra prediction
means configured to subject the neighboring pixels to the
filtering processing using the coefficient set by the filter
setting means, and performing intra prediction of the
current block; and encoding means configured to encode an
image of the current block.
[0038]
The encoding parameter may include a mode of intra
prediction of the current block, or a quantization parameter
of the current block; and the filter setting means may set
the coefficient in accordance with the mode of intra
prediction of the current block, or the quantization
parameter of the current block; and the encoding means may
encode the corresponding mode of intra prediction of the
current block or quantization parameter of the current block.
[ 0 0 3 9 ]
The image processing device may further include: filter
coefficient storage means configured to store the
coefficient; wherein the coefficient is calculated so as to
obtain, with a learning image, the smallest residual between
a learning block which is the object of encoding processing,
and a prediction image obtained by performing intra
prediction for the- learning block corresponding to a mode of
intra prediction of the learning block or a quantization
parameter of the learning block, and is stored in the filter
coefficient storage means; and wherein the filter setting
means set, as the coefficient, that from the coefficients
stored in the filter coefficient storage means which
corresponds to the mode of intra prediction of the current
block, or the quantization parameter of the current block.
[00401
The image processing device may further include: filter
coefficient calculating means configured to calculate the
coefficient such that the residual between the current block,
and a prediction image obtained by intra prediction being
performed regarding the current block, using the neighboring
pixels prior to being subjected to the filtering processing
in accordance with the mode of intra prediction of the
current block or the quantization parameter of the current
block is smallest; wherein the filter setting means set, as
the coefficient, that from the coefficients calculated by
the filter coefficient calculating means which corresponds
to the mode of intra prediction of the current block, or the
quantization parameter of the current block; and wherein the
encoding means further encode the coefficient.
[0041]
The coefficient may be configured of a filter
coefficient and offset value.
[0042]
The filter setting means may set whether or not to
perform the filtering processing as to the neighboring
pixels; and the encoding means may encode flag information
indicating whether or not to perform the filtering
processing set by the filter setting means.
[00431
An image processing method according to the second
aspect of the present invention includes the steps of: an
image processing device performing setting of a coefficient
to be used for filtering processing to which neighboring
pixels of a current block which is to be the object of
decoding processing are to be subjected to, used for intra
prediction of the current block, in accordance with an
encoding parameter; subjecting the neighboring pixels to the
filtering processing using the coefficient that has been set,
and performing intra prediction of the current block; and
encoding an image of the current block.
-
With the first aspect of the present invention, an
image of a current block which is to be the object of
decoding processing is decoded, a coefficient is set, which
is to be used for filtering processing to which neighboring
pixels of the current block are to be subjected to which are
used for intra prediction of the current block, in
accordance with an encoding parameter. The neighboring
pixels are then subjected to the filtering processing using
the coefficient that has been set, and intra prediction of
the current block is performed.
[0045]
With the second aspect of the present invention, an a
coefficient is set, to be used for filtering processing to
which neighboring pixels of a current block which is to be
the object of decoding processing are to be subjected to
which are used for intra prediction of the current block, in
accordance with an encoding parameter, the neighboring
pixels are subjected to the filtering processing using the
coefficient that has been set, intra prediction of the
current block is performed, and an image of the current
block is encoded.
[0046]
Note that the above-described image processing devices
may be stand-alone devices, or may be internal blocks making
up one image encoding device or image decoding device.
Advantageous Effects of Invention
[ 0 0 4 7 1
According to the first invention, images can be decoded.
Also, according to the second invention, noise removal can
be performed in accordance with the image and the bit rate.
[0048]
According to the second invention, images can be
encoded. Also, according to the first invention, noise
removal can be performed in accordance with the image and
the bit rate.
Brief Description of Drawings
[0049]
[Fig. 11 Fig. 1 is a block diagram illustrating the
configuration of an embodiment of an image encoding device
to which the present invention has been applied.
[Fig. 21 Fig. 2 is a diagram for describing processing
sequence in the event of a 16 x 16 pixel intra prediction
mode.
[Fig. 31 Fig. 3 is a diagram illustrating the kinds of
4 x 4 pixel intra prediction modes for luminance signals.
[Fig. 41 Fig. 4 is a diagram illustrating the kinds of
4 x 4 pixel intra prediction modes for luminance signals.
[Fig. 53 Fig. 5 is a diagram for describing the
direction of 4 x 4 pixel intra prediction.
[Fig. 61 Fig. 6 is a diagram for describing 4 x 4 pixel
intra prediction.
[Fig. 71 Fig. 7 is a diagram for describing encoding of
the 4 x 4 pixel intra prediction modes for luminance signals.
[Fig. 81 Fig. 8 is a diagram illustrating the kinds of
8 x 8 pixel intra prediction modes for luminance signals.
[Fig. 91 Fig. 9 is a diagram illustrating the kinds of
8 x 8 pixel intra prediction modes for luminance signals.
[Fig. 101 Fig. 10 is a diagram illustrating the kinds
of 16 x 16 pixel intra prediction modes for luminance
signals.
[Fig. 111 Fig. 11 is a diagram illustrating the kinds
of 16 x 16 pixel intra prediction modes for luminance
signals.
[Fig. 121 Fig. 12 is a diagram for describing 16 x 16
pixel intra prediction.
[Fig. 131 Fig. 13 is a diagram illustrating the kinds
of intra prediction modes for color difference signals.
[Fig. 141 Fig. 14 is a block diagram illustrating a
configuration example of an intra prediction unit and
neighboring pixel_interpolation filter switching unit in Fig.
1.
[Fig. 151 Fig. 15 is a diagram for describing
calculation of filter coefficients.
[Fig. 161 Fig. 16 is a flowchart for describing the
encoding processing of the image encoding device in Fig. 1.
[Fig. 171 Fig. 17 is a flowchart for describing the
prediction processing in step S21 in Fig. 16.
[Fig. 181 Fig. 18 is a flowchart for describing the
intra prediction processing in step S31 in Fig. 17.
[Fig. 191 Fig. 19 is a flowchart for describing the
inter motion prediction processing in step S32 in Fig. 1 7 .
[Fig. 201 Fig. 20 is a block diagram illustrating
another configuration example of an intra prediction unit
and neighboring pixel interpolation filter switching unit in
Fig. 1.
[Fig. 211 Fig. 21 is a flowchart for describing another
example of the intra prediction processing in step S31 in
Fig. 17.
[Fig. 221 Fig. 22 is a block diagram illustrating the
configuration of an embodiment of an image decoding device
to which the present invention has been applied.
*
[Fig. 231 Fig. 23 is a block diagram il'lustrating a
configuration example of an intra prediction unit and
neighboring pixel interpolation filter switching unit in Fig.
22.
[Fig. 241 Fig. 24 is a flowchart for describing the
decoding processing of the image decoding device in Fig. 22.
[Fig. 251 Fig. 25 is a flowchart for describing the
prediction processing in step S138 in Fig. 24.
[Fig. 261 Fig. 26 is a block diagram illustrating
another configuration example of an intra prediction unit
and neighboring pixel interpolation filter switching unit in
Fig. 22.
[Fig. 271 Fig. 27 is a flowchart for describing another
example of the prediction processing in step S138 in Fig. 24.
[Fig. 281 Fig. 28 is a block diagram illustrating the
configuration of an embodiment of a learning device to which
the present invention has been applied.
[Fig. 291 Fig. 29 is a block diagram illustrating a
configuration example of an intra prediction unit and
neighboring pixel interpolation filter calculating unit in
Fig. 28.
[Fig. 301 Fig. 30 is a flowchart for describing intra
prediction processing with the learning device in Fig. 28.
[Fig. 311 Fig. 3 1 is a block diagram illustrating the
configuration of another embodiment of an image encoding
device to which the present invention has been applied.
[Fig. 321 Fig. 32 is a diagram for describing second
order prediction processing.
[Fig. 331 Fig. 33 is a block diagram illustrating the
configuration of another embodiment of an image decoding
device to which the present invention has been applied.
[Fig. 341 Fig. 34 is a block diagram illustrating the
configuration of yet another embodiment of an image encoding
device to which the present invention has been applied.
[Fig. 351 Fig. 35 is a block diagram illustrating a
configuration example of an intra prediction unit in Fig. 34.
[Fig. 361 Fig. 36 is a flowchart for describing another
example of the intra prediction processing in step S31 in
Fig. 17.
[Fig. 371 Fig. 37 is a flowchart for describing yet
another example of the intra prediction processing in step
S31 in Fig. 17.
[Fig. 381 Fig. 38 is a flowchart for describing another
example of the intra prediction processing in step S31 in
Fig. 17.
[Fig. 391 Fig. 39 is a block diagram illustrating the
configuration of yet another embodiment of an image decoding
device to which the present invention has been applied.
[Fig. 401 Fig. 40 is a block diagram illustrating a
configuration example of an intra prediction unit and
neighboring pixel interpolation filter control unit in Fig.
39.
[Fig. 411 Fig. 41 is a flowchart for describing yet
another example of the prediction processing in step S138 in
Fig. 24.
[Fig. 421 Fig. 42 is a block diagram illustrating the
configuration of another embodiment of an image encoding
device to which the present invention has been applied.
[Fig. 431 Fig. 43 is a block diagram illustrating the
configuration of another embodiment of an image decoding
device to which the present invention has been applied.
[Fig. 441 Fig. 44 is a diagram illustrating an example
of an extended block size.
[Fig. 451 Fig. 45 is a block diagram illustrating a
configuration example of the hardware of a computer.
[Fig. 461 Fig. 46 is a block diagram illustrating a
principal configuration example of a television receiver to
which the present invention has been applied.
[Fig. 471 Fig. 47 is a block diagram illustrating a
principal configuration example of a cellular phone to which
the present invention has been applied.
[Fig. 481 Fig. 48 is a block diagram illustrating a
principal configuration example of a hard disk recorder to
which the present invention has been applied.
[Fig. 491 Fig. 49 is a block diagram illustrating a
principal configuration example of a camera to which the
present invention has been applied.
Description of Embodiments
[0050]
Hereinafter, embodiments of the present invention will
be described with reference to the drawings. Note that
description will proceed in the following order.
1. First Embodiment (neighboring pixel interpolation filter
switching: example of intra prediction)
2. Second Embodiment (neighboring pixel interpolation
filter switching: example of second order prediction)
3. Third Embodiment (neighboring pixel interpolation filter
on/off control: example of intra prediction) ..
4. Fourth Embodiment (neighboring pixel interpolation
filter on/off control: example of second order prediction)
[00511
<1. First Embodiment>
[Configuration Example of Image Encoding Device]
Fig. 1 represents the configuration of an embodiment of
an image encoding device serving as an image processing
device to which the present invention has been applied.
[00521
This image encoding device 51 subjects an image to
compression encoding using, for example, the H.264 and MPEG-
4 Part10 (Advanced Video Coding) (hereafter, described as
H.264/AVC) format.
[0053]
With the example in Fig. 1, the image encoding device
51 is configured of an A/D conversion unit 61, a screen
rearranging buffer 62, a computing unit 63, an orthogonal
transform unit 64, a quantization unit 65, a lossless
encoding unit 66, an storing buffer 67, an inverse
quantization unit 68, an inverse orthogonal transform unit
69, a computing unit 70, a deblocking filter 71, frame
memory 72, a switch 73, an intra prediction unit 74, a
neighboring pixel interpolation filter switching unit 75, a
motion prediction/compensation unit 76, a prediction image
selecting unit 77, and a rate control unit 78.
[0054]
The A/D conversion unit 61 converts an input image from
analog to digital, and outputs to the screen rearranging
buffer 62 for storing. The screen rearranging buffer 62
rearranges the images of frames in the stored order for
display into the order of frames for encoding according to
GOP (Group of Picture).
[00551
The computing unit 63 subtracts from the image read out
from the screen rearranging buffer 62 the prediction image
from the intra prediction unit 74 selected by the prediction
image selecting unit 77 or the prediction image from the
motion prediction/compensation unit 76, and outputs
difference information thereof to the orthogonal transform -
unit 64. The orthogonal transform unit 64 subjects the
difference information from the computing unit 63 to
orthogonal transform, such as discrete cosine transform,
Karhunen-Lo6ve transform, or the like, and outputs a
transform coefficient thereof. The quantization unit 65
quantizes the transform coefficient that the orthogonal
transform unit 64 outputs.
[0056]
The quantized transform coefficient that is the output
of the quantization unit 65 is input to the lossless
encoding unit 66, where it is subjected to lossless encoding,
such as variable length coding, arithmetic coding, or the
like, and compressed.
[0057]
The lossless encoding unit 66 obtains information
indicating intra prediction and so forth from the intra
prediction unit 74, and obtains information indicating an
inter prediction mode, and so forth from the motion
prediction/compensation unit 76. Note that the information
indicating intra prediction will also be referred to as
intra prediction mode information hereinafter. Also, the
information indicating inter prediction will also be
referred to as inter prediction mode information hereinafter.
[0058]
The lossless encoding unit 66 encodes the quantized
transform coefficient, and also encodes the information
indicating intra prediction, the information indicating an
inter prediction mode, quantization parameters, and so forth,
and takes these as part of header information in the
compressed image. The lossless encoding unit 66 supplies
the encoded data to the storing buffer 67 for storage.
[0059]
For example, with the lossless encoding unit 66,
lossless encoding processing, such as variable length coding,
arithmetic coding, or the like, is performed. Examples of
the variable length coding include CAVLC (Context-Adaptive
Variable Length Coding) determined by the H.264/AVC format.
Examples of the arithmetic coding include CABAC (Context-
Adaptive Binary Arithmetic Coding).
[0060]
The storing buffer 67 outputs the data supplied from
the lossless encoding unit 66 to, for example, a storage
device or transmission path or the like downstream not shown
in the +awing, as. a compressed image encoded by the
H. 264/AVC f ormat.
[0061]
Also, the quantized transform coefficient output from
the quantization unit 65 is also input to the inverse
quantization unit 68, subjected to inverse quantization, and
then subjected to further inverse orthogonal transform at
the inverse orthogonal transform unit 69. The output
subjected to inverse orthogonal transform is added to the
prediction image supplied from the prediction image
selecting unit 77 by the computing unit 70, and changed into
a locally decoded image. The deblocking filter 71 removes
block distortion from the decoded image, and then supplies
to the frame memory 72 for storage. An image before the
deblocking filter processing is performed by the deblocking
filter 71 is also supplied to the frame memory 72 for
storage.
[0062]
The switch 73 outputs the reference images stored in
the frame memory 72 to the motion prediction/compensation
unit 76 or intra prediction unit 74.
[0063]
With this image encoding device 51, the I picture, B
picture, and P picture from the screen rearranging buffer 62
are supplied to the intra prediction unit 74 as an image to
be subjected to intra prediction (also referred to as intra
processing), for example. Also, the B picture and P picture
read out from the screen rearranging buffer 62 are supplied
to the motion prediction/compensation unit 76 as an image to
be subjected to inter prediction (also referred to as inter
processing) .
[0064]
The intra prediction unit 74 performs intra prediction
processing of all of the candidate intra prediction modes
based on the image to be subjected to intra prediction read
out from the screen rearranging buffer 62, and the reference
image supplied from the frame memory 72 to generate a
prediction image.
[0065]
Prior to the intra prediction processing, the intra
prediction unit 74 performs filtering professing on
neighboring pixels which are pixels used for intra
prediction of each current block, and neighboring the
current block with a predetermined positional relation.
This filtering processing uses a filter coefficient set by a -
neighboring pixel interpolation filter switching unit 75, in
accordance with the intra prediction mode supplied from the
intra prediction unit 74, and so forth. That is to say, the
intra prediction unit 74 uses, for intra prediction
processing of all candidate intra prediction modes,
neighboring pixels subjected to filtering processing with
filter coefficients set by the neighboring pixel
interpolation filter switching unit 75.
[00661
The intra prediction unit 74 calculates a cost function
value as to the intra prediction mode where the prediction
image bas been generated, and selects the intra prediction
mode where the calculated cost function value gives the
minimum value, as the optimal intra prediction mode. The
intra prediction unit 74 supplies the prediction image
generated in the optimal intra prediction mode, and the cost
function value calculated regarding the corresponding
optimal intra prediction mode, to the prediction image
selecting unit 77.
[0067]
In the event that the prediction image generated in the
optimal intra prediction mode has been selected . by the
prediction image selecting unit 77, the intra prediction
unit 74 supplies information indicating the optimal intra
prediction mode to the lossless encoding unit 66. In the
event that the information has been transmitted from the
intra prediction unit 74, the lossless encoding unit 66
encodes this information, and takes this as part of the
header information in the compressed image.
[0068]
The neighboring pixel interpolation filter switching
unit 75 stores the filter coefficients corresponding to
quantization parameters and intra prediction modes obtained
by performing learning at a learning device 251 in Fig. 28
which will be described later, using a training image.
[0069]
The neighboring pixel interpolation filter switching
unit 75 is supplied with quantization parameters from the
rate control unit 78 and intra prediction mode information
from the intra prediction unit 74. The neighboring pixel
interpolation filter switching unit 75 sets filter
coefficients corresponding to the quantization parameters
from the rate control unit 78 and the intra prediction mode
from the intra prediction unit 74. The neighboring pixel
interpolation filter switching unit 75 supplies the set
filter coefficients to the intra prediction unit 74.
[0070]
Note that the neighboring pixel interpolation filter
switching unit 75 may perform learning and storing of filter
coefficients corresponding to just one, rather than both, of
quantization parameters and intra prediction modes.
[0071]
Also, while the neighboring pixel interpolation filter
switching unit 75 stores filter coefficients learned offline
beforehand, filter coefficients may be calculated online
instead. In this case, filter coefficients set by the
neighboring pixel interpolation filter switching unit 75 are
output to the lossless encoding unit 66 to be sent to the
decoding side, as indicated by the dotted arrow.
[0072]
The motion prediction/compensation unit 76 performs
motion prediction and compensation processing regarding all
of the candidate inter prediction modes. Specifically, the
motion prediction/compensation unit 76 is supplied with the
image to be subjected to inter processing read out from the
screen rearranging buffer 62, and the reference image from
the frame memory 7.2 via the switch 73. The motion
prediction/compensation unit 76 detects the motion vectors
of all of the candidate inter prediction modes based on the
image to be subjected to inter processing and the reference
image, subjects the reference image to compensation
processing based on the motion vectors, and generates a
prediction image.
[ 0 0 7 3 ]
Also, the motion prediction/compensation unit 76
calculates a cost function value as to all of the candidate
inter prediction modes. The motion prediction/compensation
unit 76 determines, of the calculated cost function values,
the prediction mode that provides the minimum value to be
the optimal inter prediction mode.
LO0741
The motion prediction/compe'nsation unit 76 supplies the
prediction image generated in the optimal inter prediction
mode, and the cost function value thereof to the prediction
image selecting unit 77. In the event that the prediction
image generated in the optimal inter prediction mode by the
prediction image selecting unit 77 has been selected, the
motion prediction/compensation unit 76 outputs information
indicating the optimal inter prediction mode (inter
prediction mode information) to the lossless encoding unit
66.
[0075]
Note that the motion vector information, flag
information, reference frame information, and so forth are
output to the lossless encoding unit 66 according to need.
The lossless encoding unit 66 also subjects the information
from the motion prediction/compensation unit 76 to lossless
encoding processing such as variable length coding,
arithmetic coding, or the like, and inserts into the header
portion of the compressed image.
to0761
The prediction image selecting unit 77 determines the
optimal prediction mode from the optimal intra prediction
mode and the optimal inter prediction mode based on the cost
function values output from the intra prediction unit 74 or
motion prediction/compensation unit 76. The prediction
image selecting unit 77 then selects the prediction image in
the determined optimal prediction mode, and supplies to the
computing units 63 and 70. At this time, the prediction
image selecting unit 77 supplies the selection information
of the prediction image to the intra prediction unit 74 or
motion prediction/compensation unit 76.
[00771
The rate control unit 78 controls the rate of the
quantization operation of the quantization unit 65 with
quantization parameters, based on a compressed image stored
in the storing buffer 67, so as not to cause overflow or
underflow.
[0078]
The quantization parameter used for rate control at the
quantization unit 65 is supplied to the lossless encoding
unit 66, subjected to lossless encoding processing, and
inserted to the header portion of the compressed image.
This quantization parameter is supplied to the neighboring
pixel interpolation filter switching unit 75, and used for
setting filter coefficients used for filter processing to be
applied to neighboring pixels.
[0079]
[Description of Intra Prediction Processing According to
H.264/AVC format]
First, the intra prediction modes determined by the
H.264/AVC format will be described.
[0080]
First, the intra prediction modes as to luminance
signals will be described. With the intra prediction modes
*
for luminance signals, three systems of an intra 4 x 4
prediction mode, an intra 8 x 8 prediction mode, and an
intra 16 x 16 prediction mode are determined. These are
modes for determining block units, and are set for each
macro block. Also, an i n t r a p r e d i c t i o n mode may be s e t t o
c o l o r d i f f e r e n c e s i g n a l s independently from luminance
s i g n a l s f o r each macro block.
[0081]
Further, i n t h e event of the i n t r a 4 x 4 p r e d i c t i o n
mode, one p r e d i c t i o n mode can be s e t out of the nine kinds
of p r e d i c t i o n modes f o r each 4 x 4 p i x e l c u r r e n t block. In
the event of the i n t r a 8 x 8 p r e d i c t i o n mode, one p r e d i c t i o n
mode can be s e t out of the nine kinds of p r e d i c t i o n modes
f o r each 8 x 8 p i x e l c u r r e n t block. Also, i n the event of
the i n t r a 1 6 x 16 p r e d i c t i o n mode, one p r e d i c t i o n mode can
be s e t t o a 1 6 x 16 p i x e l c u r r e n t macro block out of the
four kinds of p r e d i c t i o n modes.
[0082]
Note t h a t , h e r e a f t e r , t h e i n t r a 4 x 4 p r e d i c t i o n mode,
i n t r a 8 x 8 p r e d i c t i o n mode, and i n t r a 16 x 16 p r e d i c t i o n
mode w i l l a l s o be r e f e r r e d t o as 4 x 4 p i x e l i n t r a
p r e d i c t i o n mode, 8 x 8 p i x e l i n t r a p r e d i c t i o n mode, and 16 x
16 p i x e l i n t r a p r e d i c t i o n mode as - appropriate, r e s p e c t i v e l y .
[0083]
With the example i n Fig. 2, numerals -1 through 25
appended t o the blocks r e p r e s e n t t h e b i t stream sequence
(processing sequence on the decoding s i d e ) of the blocks
t h e r e o f . Note t h a t , w i t h regard t o luminance s i g n a l s , a
macro block i s divided i n t o 4 x 4 p i x e l s , and DCT of 4 x 4
pixels is performed. Only in the event of the intra 16 x 16
prediction mode, as shown in a block of -1, the DC
components of the blocks are collected, a 4 x 4 matrix is
generated, and this is further subjected to orthogonal
transform.
[0084]
On the other hand, with regard to color difference
signals, after a macro block is divided into 4 x 4 pixels,
and DCT of 4 x 4 pixels is performed, as shown in the blocks
16 and 17, the DC components of the blocks are collected, a
2 x 2 matrix is generated, and this is further subjected to
orthogonal transform.
[0085]
Note that, with regard to the intra 8 x 8 prediction
mode, this may be applied to only a case where the current
macro block is subjected to 8 x 8 orthogonal transform with
a high profile or a profile beyond this.
Fig. 3 and Fig. 4 are diagrams showing nine kinds of 4
x 4 pixel intra prediction modes (Intra-4x4-pred-mode) for
luminance signals. The eight kinds of modes other than the
mode 2 showing average value (DC) prediction correspond to
directions indicated with numbers 0, 1, 3 through 8 in Fig.
5, respectively.
[0087]
The nine kinds of intra - 4x4-pred - mode will be described
with reference to Fig. 6. With the example in Fig. 6,
pixels a through p represent the pixels of the current block
to be subjected to intra processing, and pixel values A
through M represent the pixel values of pixels belonging to
a neighboring block. Specifically, the pixels a through p
are an image to be processed read out from the screen
rearranging buffer 62, and the pixel values A through M are
the pixel values of a decoded image to be read out from the
frame memory 72 and referenced.
[ 0 0 8 8 ]
In the case of the intra prediction modes shown in Fig.
3 and Fig. 4, the-prediction pixel values of the pixels a
through p are generated as follows using the pixel values A
through M of the pixels belonging to a neighboring block.
Here, that a pixel value is "available" represents that the
pixel value is available without a reason such that the
pixel is positioned in the edge of the image frame, or has
not been encoded yet. On the other hand, that a pixel value
is "unavailable1' represents that the pixel value is
unavailable due to a reason such that the pixel is
positioned in the edge of the image frame, or has not been
encoded yet.
[ 0 0 8 9 ]
The mode 0 is a Vertical Prediction mode, and is
applied to only a case where the pixel values A through D
are "available". In this case, the prediction pixel values
of the pixels a through p are generated as with the
following Expression (1) .
Prediction pixel values of pixels a, e, i, and m = A
Prediction pixel values of pixels b, f, j, and n = B
Prediction pixel values of pixels c, g, k, and o = C
Prediction pixel values of pixels d, h, 1, and p = D . . .
(1
[0090]
The mode 1 is a Horizontal Prediction mode, and is
applied to only a case where the pixel values I through L
are "available". In this case, the prediction pixel values
of the pixels a through p are generated as with the
following Expression (2) .
Prediction pixel values of pixels a, b, c, and d = I
Prediction pixel values of pixels el f, g, and h = J
Prediction pixel values of pixels i, j, k, and 1 = K
Prediction pixel values of pixels m, n, o, and p = L . . .
(2)
[0091]
The mode 2 is a DC Prediction mode, and the prediction
pixel value is generated like Expression (3) when the pixel
values A, B, C, D, I, J, K, and L are all "available".
[0092]
Also, when the pixel values A, B, C, and D are all
"unavailable", the prediction pixel value is generated like
Expression (4).
( I + J t K + L + 2 ) > > 2 . . . ( 4 )
[0093]
Also, when the pixel values I, J, K, and L are all
"unavailable", the prediction pixel value is generated like
Expression ( 5 ) .
( A + B + C + D + 2 ) > > 2 . . . (5)
[0094]
Note that, when the pixel values A, B, C, Dl I, J, K,
and L are all "unavailable", 1 2 8 is employed as the
prediction pixel value.
[0095]
The mode 3 is a Diagonal - Down - Left Prediction mode, and
is applied to only a case where the pixel values A, B, C, D,
I, J, K, L, and M are "available". In this case, the
prediction pixel values of the pixels a through p are
generated as with the following Expression (6).
Prediction pixel value of pixel a = (A + 2B + C + 2) >> 2
Prediction pixel values of pixels b and e = (B + 2C + D + 2 )
>> 2
Prediction pixel values of pixels c, f, and i = (C + 2D + E
+ 2 ) >> 2
Prediction pixel values of pixels d, g, j, and m = (D + 2E -t
F + 2 ) >> 2
Prediction pixel values of pixels h, k, and n = (E + 2F + G
t 2 ) >> 2
Prediction pixel values of pixels 1 and o = (F t 2G t H + 2)
>> 2
Prediction pixel value of pixel p = (G + 3H t 2) >> 2 . . .
(6)
[00961
The mode 4 is a Diagonal-Down-Right Prediction mode,
and is applied to only a case where the pixel values A, 8, C,
D, I, J, K, L, and M are "available". In this case, the
prediction pixel values of the pixels a through p are
generated as with the following Expression (7).
Prediction pixel value of pixel m = (J + 2K t L + 2) >> 2
Prediction pixel values of pixels i and n = (I + 2J + K + 2)
>> 2
Prediction pixel values of pixels e, j, and o = (M + 21 + J
+ 2) >> 2
Prediction pixel values of pixels a, f, k, and p = (A + 2M +
I + 2) .> 2
Prediction pixel values of pixels b, g, and 1 = (M + 2A + B
+ 2) >> 2
Prediction pixel values of pixels c and h = (A + 2B + C + 2 )
>> 2
Prediction pixel value of pixel d = (B t 2C t D + 2) >>
The mode 5 is a Diagonal - Vertical-Right Prediction mode,
and is applied to only a case where the pixel values A, B, C,
D, I, J, K, L, and M are "available". In this case, the
prediction pixel values of the pixels a through p are
generated as with the following Expression (8).
Prediction pixel values of pixels a and j = (M t A + 1) >> 1
Prediction pixel values of pixels b and k = (A + B t 1) >> 1
Prediction pixel values of pixels c and 1 = (B + C + 1) >> 1
Prediction pixel value of pixel d = (C t D + 1) >> 1
Prediction pixel values of pixels e and n = (I + 2M t A + 2)
>> 2
Prediction pixel values of pixels f and o = (M + 2A t B t 2)
>> 2
Prediction pixel values of pixels g and p = (A + 2B t C + 2)
>> 2
Prediction pixel value of pixel h = (B t 2C t D + 2) >> 2
Prediction pixel value of pixel i = (M + 21 + J + 2) >> 2
Prediction pixel value of pixel m = (I t 2J t K t 2) >>
2 . . . (8)
[0098]
The mode 6 is a Horizontal - Down Prediction mode, and is
applied to only a case where the pixel values A, B, C, Dl I,
J, K, L, and M are "available". In this case, the
prediction pixel values of the pixels a through p are
generated as with the following Expression ( 9 ) .
Prediction pixel values of pixels a and g = (M t I + 1) >> 1
Prediction pixel values of pixels b and h = (I t 2M + A + 2)
>> 2
Prediction pixel value of pixel c = (M + 2A + B t 2) >> 2
Prediction pixel value of pixel d = (A + 2B + C t 2) >> 2
Prediction pixel values of pixels e and k = (I t J + 1) >> 1
Prediction pixel values of pixels f and 1 = (M + 21 + J + 2)
>> 2
Prediction pixel values of pixels i and o = (J + K + 1) >> 1
Prediction pixel values of pixels j and p = (I + 2J t K + 2)
>> 2
Prediction pixel value of pixel m = (K + L + 1) >> 1
Prediction pixel value of pixel n = (J + 2K + L + 2) >>
2 . . . (9)
[0099]
The mode 7 is a Vertical - Left Prediction mode, and is
applied to only a case where the pixel values A, B, C, D, I,
J, K, L, and M are "available". In this case, the
prediction pixel values of the pixels a through p are
generated as with the following Expression (10).
Prediction pixel value of pixel a = (A + B + 1) >> 1
Prediction pixel values of pixels b and i = (B + C + 1) >> 1
Prediction pixel values of pixels c and j = (C + D + 1) >> 1
Prediction pixel va1u.e~ of pixels d and k = (D + E + 1) >> 1
Prediction pixel value of pixel 1 = (E t F + 1) >> 1
Prediction pixel value of pixel e = (A + 2B + C + 2) >> 2
Prediction pixel values of pixels f and m = (B + 2C + D + 2)
>> 2
Prediction pixel values of pixels g and n = (C + 2D + E t 2)
>> 2
Prediction pixel values of pixels h and o = (D + 2E + F + 2)
Prediction pixel value of pixel p = (E t 2F + G + 2) >>
The mode 8 is a Horizontal - Up Prediction mode, and is
applied to only a case where the pixel values A, B, C, D, I,
J, K, L, and M are "available". In this case, the
prediction pixel values of the pixels a through p are
generated as with the following Expression (11).
Prediction pixel value of pixel a = (I t J + 1) >> 1
Prediction pixel value of pixel b = (I t 2J + K + 2) >> 2
Prediction pixel values of pixels c and e = (J + K + 1) >> 1
Prediction pixel values of pixels d and f = (J + 2K + L + 2)
>> 2
Prediction pixel values of pixels g and i = (K + L + 1) >> 1
Prediction pixel values of pixels h and j = (K + 3L + 2) >>
Prediction pixel values of pixels k, 1, m, n, o, and p =
[OlOl]
Next, the encoding format of the 4 x 4 pixel intra
prediction mode (Intra-4x4 - pred - mode) for luminance signals
will be described with reference to Fig. 7. With the
example in Fig. 7, an current block C serving as an encoding
object, which is made up of 4 x 4 pixels, is shown, and a
block A and a block B, which neighbor the current block C
and are made up of 4 x 4 pixels, are shown.
[0102]
In this case, it can be conceived that the
Intra - 4x4 - pred - mode in the current block C, and the
Intra - 4x4-pred-mode in the block A and block B have high
correlation. Encoding processing is performed as follows
using this correlation, whereby higher encoding efficiency
can be realized.
[0103]
Specifically, with the example in Fig. 7, the
Intra - 4x4pred-mode in the block A and block B are taken as
Intra - 4x4pred-modeA and Intra-4x4pred-modeB respectively,
and MostProbableMode is defined as the following Expression
(12) -
MostProbableMode = Min(1ntra - 4~4pred_modeA,
Intra - 4x4 - pred - modeB) . . . (12)
[0104]
That is to say, of the block A and block B, one to
which a smaller mode - number is assigned is taken as
MostProbableMode. _
[0105]
Two values called
prev - intra4x4 - pred - mode flag[luma4x4Blkldx] and
rem - intra4x4 - pred - mode[luma4x4Blkldx] are defined within a
bit stream as parameters as to the current block C, and
decoding processing is performed by processing based on the
.Li
pseudo-code shown in the following Expression (13), whereby
the values of Intra - 4x4 - pred - mode and
Intra4~4PredMode[luma4~4Blkldx]a s to the block C can be
obtained.
[0106]
If(prev - intra4x4pred - mode - flag[luma4~4Blkldx])
Intra4x4PredMode[luma4~4Blkldxl = MostProbableMode
else
if (rem - intra4x4gred - mode [luma4x4Blkldx] <
MostProbableMode)
Intra4x4PredMode [luma4~4Blkldx]=
rem - intra4x4 - pred - mode[luma4x4Blkldx]
else
Intra4~4PredMode[luma4~4B1k1dx=]
[0107]
Next, the 8 x - 8 pixel intra prediction mode will be
described. Fig. 8 and Fig. 9 are diagrams showing the nine
kinds of 8 x 8 pixel intra prediction modes
(intra- 8 x8- p red-mode) for luminance signals.
[0108]
Let us say that the pixel values in the current 8 x 8
block are taken as p[x, y] (0 I x I 7; 0 5 y I 7 ) , and the
pixel values of a neighboring block are represented like p[-
1, -11, ..., p[-1, 151, p[-1, 01, ..., [p-1, 71.
[0109]
With regard to the 8 x 8 pixel intra prediction modes,
neighboring pixels are subjected to low-pass filtering
processing prior to generating a prediction value. Now, let
us say that pixel values before low-pass filtering
processing are represented with p [-1, -11, ..., p [-1, 151, p [-
1, 01, ..., p [-1, 71, and pixel values after the processing
are represented with p' [-1, -11, ..., p' [-I, 151 I P' [-I, 01 ... I
First, p' [O, -11 is calculated as with the following
Expression (14) in. the event that p [-1, -11 is "available",
and cal'culated as with t,he following Expression (15) in the
event of "not available".
p' [O, -11 = (p[-1, -11 + 2*p[0, -11 t p [ l , -11 + 2) >>
2 . . . (14)
p' [O, -11 = (3*p[O, -11 + p[l, -11 + 2) >> 2 . . . (15)
[Olll]
p' [x, -11 (x = 0, ..., 7) is calculated as with the
following Expression (16) .
[0112]
p' [x, -11 (x = 8, ..., 15) is calculated as with the
following Expression (17) in the event that p[x, -11 (x = 8,
..., 15) is "available".
p' [x, -11 = (p[x-1, -11 4- 2*p[x, -11 t p[x+l, -11 t 2) >> 2
p1[15, -11 = (p[14, -11 + 3*p[15, -11 + 2) >> 2 . . . (17)
[0113 I
pl[-1, -11 is calculated as follows in the event that
p[-1, -11 is "available". Specifically, p' [-1, -11 is
calculated like Expression (18) in the event that both of
p [Or -11 and p [-1, 01 are "available", and calculated like
Expression (19) in the event that p[-1, 01 is "unavailable".
Also, p' [-1, -11 is calculated like Expression (20) in the
event that p [ 0, -11 is "unavailable".
p' 1-1, -11 = (p[O, -11 + 2*p[-1, -11 + p[-1, 01 + 2) >>
2 . . . (18)
p' [-1, -11 = (3*p[-1, -11 t pC0, -11 + 2) >> 2 . . . (19)
p'[-1, -11 = (3*p[-1, -11 + p[-1, 01 + 2) >> 2 . . . (20)
[0114]
p' [-1, y] (y = 0, ..., 7) is calculated as follows when
p[-1, y] (y = 0, ..., 7) is "available". Specifically, first,
in the event that p [-1, -11 is "available", p' [-1, 01 is
calculated as with the following Expression (21), and in the
event of "unavailable", calculated like Expression (22).
Also, p' [-1, yl (y = I, ..., 6) is calculated as with the
following Expression (23), and p'[-1, 71 is calculated like
Expression (24) .
p[-1, y] = (p[-1, y-11 + 2*p[-1, yl + p[-1, y+ll + 2) >>
2 . . . (23)
pl[-1, 71 = (p[-1, 61 + 3*p[-1, 71 + 2) >> 2 . . . (24)
Prediction values in the intra prediction modes shown
in Fig. 8 and Fig. 9 are generated as follows using p' thus
calculated.
[0117]
The mode 0 is a Vertical Prediction mode, and is
applied only when p[x, -11 (x = 0, ..., 7) is "available". A
prediction value pred8~8~[xy,] is generated as with the
following Expression (25).
pred8xEL[x, y] = p' [x, -11 x, y = 0, ..., 7 . . . (25)
[0118]
The mode 1 is a Horizontal Prediction mode, and is
applied only when p[-1, y] (y = 0, ..., 7) is "available".
The prediction value pred8~8~[xy,] is generated as with the
following Expression (26) .
pred8~8~[xy,] = p' [-1, y] x, y = 0, ..., 7 . . . (26)
[0119]
The mode 2 is a DC Prediction mode, and the prediction
value pred8x8~[ x, yl is generated as follows. Specifically,
in the event that both of p[x, -11 (x = 0, ..., 7) and p [-1,
yl (y = 0, ..., 7) are "available", the prediction value
pred8~8~[xy,] is generated as with the following Expression
(27).
[Mathematical Expression 11
[0120] -
In the event that p[x, -11 (x = 0, ..., 7) is "available",
but p[-1, y ] (y = 0, ..., 7) is "unavailable", the prediction
value pred8~8~[xy,] is generated as with the following
Expression (28).
[Mathematical Expression 21
d=O
101211
In the event that p [x, -11 (x = 0, ..., 7) is
"unavailable", but p[-1, y] (y = 0, ..., 7) is "available",
the prediction value pred8~8~[xy,] is generated as with the
following Expression (29) .
[Mathematical Expression 31
7
In the event that both of p[x, -11 (x = 0, ..., 7) and
p[-1, y] (y = 0, ..., 7) are "unavailable", the prediction
value pred8~8~[xy,] is generated as with the following
Expression (30).
pred8~8~[x,y] = 128 . . . (30)
Here, Expression (30) represents a case of 8-bit input.
[0123]
The mode 3 is a Diagonal - Down - Left - prediction mode, and
the prediction value pred8x8~[x, y] is generated as follows.
Specifically, the Diagonal - Down - Left - prediction mode is
applied only when p[x, -11, x = 0, ..., 15, is "available",
and the prediction pixel value with x =7 and y =7 is
generated as with the following Expression (31), and other
prediction pixel values are generated as with the following
Expression (32).
pred8~8~[x,y] = (p'[ 14, -11 + 3*p[15, -11 + 2) >> 2 . . .
[0124]
The mode 4 is a Diagnonal - Down - Right-prediction mode,
and the prediction value pred8x8,[xr y] is generated as
follows. Specifically, the Diagnonal - Down - Right - prediction
mode is applied only when p[x, -11, x = 0, ..., 7 and p[-1, y],
y = 0, ..., 7 are "available", the prediction pixel value with
x > y is generated as with the following Expression (33),
and the prediction pixel value with x < y is generated as
with the following Expression (34). Also, the prediction
pixel value with x = y is generated as with the following
Expression (35).
pred8~8~[x,y] = (p'[ x-y-2, -11 + 2*p1[ x-y-1, -11 + p' [x-y, -
11 + 2) >> 2 . . . (33)
pred8x8=[xr y] = (p' [-1, y-x-21 + 2*pV [-I, y-x-l] + p' [-1, y-
XI + 2) >> 2 . . . (34)
pred8~8~[xy,] = (p'[ 0, -11 + 2*pt[ -I, -11 + p' [-1, 01 + 2)
>> 2 . . . (35)

We claim:
1. An image processing device comprising:
I filter control means configured to instruct whether or not neighboring pixels of a
I current block are to be filtered, responsive to an intra-prediction mode;
I intra prediction means configured to subject said neighboring pixels to said filtering
I processing as instructed by said filter control means, and performing intra prediction of said
I current block; and
encoding means configured to encode an image of said current block.
2. The image processing device comprising according to Claim 1,
wherein said encoding means encode the mode of intra prediction of said current
block;
and wherein a filter setting means set a coefficient in accordance with the mode of
intra prediction decoded by said decoding means, wherein said coefficient is configured of a
filter coefficient and offset value.
3. The image processing device comprising according to Claim 2, wherein said filter
coefficient is configured of three taps.
4. The image processing device according to Claim 2, wherein said filter coefficient has
symmetry centered on a coefficient corresponding to zero-phase.
I 5. An image processing method comprising the steps of:
instructing whether the neighboring pixels of a current block are to be filtered, in
response to an intra-prediction mode;
subjecting said neighboring pixels to said filtering processing as instructed by said filter
control means, and performing intra prediction of said current block; and
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encoding an image of said current block.
6. The image processing method as claimed in claim 5 wherein said encoding encodes the
mode of intra prediction of said current block; and
a coefficient in accordance with the mode of
intra prediction decoded by said decoding means is set, wherein said coefficient is configured of
a filter coefficient and offset value.
7. The image processing method as claimed in claim 6 wherein the step of configuring filter
coefficient is of three taps.
8. The image processing method as claimed in claim 6 wherein said filter coefficient has
symmetry centered on a coefficient corresponding to zero-phase.