FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
“TRANSMISSION DEVICE, TRANSMISSION METHOD, RECEPTION
DEVICE, AND RECEPTION METHOD”
SONY CORPORATION, of 1-7-1, Konan, Minato-ku, Tokyo 108-
0075, Japan
The following specification particularly describes the
invention and the manner in which it is to be performed.
2
DESCRIPTION
TRANSMISSION DEVICE, TRANSMISSION METHOD, RECEPTION DEVICE,
AND RECEPTION METHOD
5 TECHNICAL FIELD
[0001]
The present technology relates to a transmission device,
a transmission method, a reception device and a reception
method, particularly to a transmission device and the like
10 transmitting transmission video data that is obtained by
application of a predetermined opto-electrical transfer
function to input video data.
BACKGROUND ART
15 [0002]
A video service using a high dynamic range (HDR) is one
that reflects the intention of a production side and supplies
a video service with a wide brightness range to allow a receiver
side to reproduce the video, thereby realizing reproduction
20 of display close to the perception of a human eye in nature.
[0003]
Non-Patent Document 1 for example discloses
transmission of a video stream that is generated by encoding
transmission video data obtained by application of a gamma
25 curve to input video data having a level of 0 to 100% * N (where
N is larger than one).
[0004]
The peak brightness of a monitor (CE monitor) on the
receiver side varies widely depending on a device
30 characteristic, a backlight arrangement and a design technique
of a display panel and may be too bright or dark compared to
3
a master monitor used in program production. This can possibly
cause improper reproduction of the feel of brightness intended
by the production side.
5 CITATION LIST
NON-PATENT DOCUMENT
[0005]
Non-Patent Document 1: High Efficiency Video Coding (HEVC)
text specification draft 10 (for FDIS & Last Call)
10
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0006]
An object of the present technology is to enable the
15 reception side to satisfactorily reproduce the feel of
brightness intended by the production side.
SOLUTIONS TO PROBLEMS
[0007]
20 A concept of the present technology is a transmission
device including:
a processing unit that acquires transmission video data
by applying a predetermined opto-electrical transfer function
to input video data; and
25 a transmission unit that transmits the transmission
video data along with region information indicating a region
in which a brightness conversion is allowed.
[0008]
In the present technology, the processing unit applies
30 the predetermined opto-electrical transfer function to the
input video data to acquire the transmission video data. The
4
input video data is for example video data of a high dynamic
range (HDR) image with a contrast ratio of 0 to 100% * N (where
N is a number larger than 1) exceeding brightness of the white
peak in a conventional low dynamic range (LDR) image.
5 [0009]
The transmission video data is transmitted by the
transmission unit along with the region information indicating
the region in which the brightness conversion is allowed. The
transmission unit may transmit a video stream acquired by
10 encoding the transmission video data, and there may be further
provided an information insertion unit that inserts the region
information into a layer of the video stream, for example.
[0010]
In this case, for example, the information insertion
15 unit may be adapted to insert metadata as the region information,
the metadata indicating the region in which the brightness
conversion is allowed. Moreover, for example, the
information insertion unit may be adapted to insert, as the
region information, a piece of information specifying the
20 predetermined opto-electrical transfer function with which
the region allowing the brightness conversion is associated.
Furthermore, for example, the region information may include
information of a plurality of regions each having a different
allowable level of the brightness conversion.
25 [0011]
According to the present technology, the transmission
video data is transmitted along with the region information
indicating the region in which the brightness conversion is
allowed. As a result, the feel of brightness intended by the
30 production side can be satisfactorily reproduced on the
reception side.
5
[0012]
Moreover, another concept of the present technology is
a reception device including:
a reception unit that receives transmission video data
5 acquired by applying a predetermined opto-electrical transfer
function to input video data along with region information
indicating a region in which a brightness conversion is
allowed; and
a processing unit that applies an electro-optical
10 transfer function corresponding to the predetermined
opto-electrical transfer function to the transmission video
data and acquires output video data by performing brightness
conversion processing on the basis of the region information.
[0013]
15 The reception unit receives the transmission video data
along with the region information indicating the region in
which the brightness conversion is allowed. The transmission
video data is acquired by applying the predetermined
opto-electrical transfer function to the input video data.
20 The input video data is for example video data of a high dynamic
range (HDR) image with a contrast ratio of 0 to 100% * N (where
N is a number larger than 1) exceeding brightness of the white
peak in a conventional low dynamic range (LDR) image. The
processing unit then applies, to the transmission video data,
25 an electro-optical transfer function or the like inverse of
and corresponding to the predetermined opto-electrical
transfer function and performs brightness conversion
processing on the basis of the region information to acquire
the output video data.
30 [0014]
The reception unit may receive a video stream acquired
6
by encoding the transmission video data, and the region
information may be inserted into a layer of the video stream,
for example. In this case, for example, metadata may be
inserted as the region information, the metadata indicating
5 the region in which the brightness conversion is allowed.
Moreover, for example, a piece of information specifying the
predetermined opto-electrical transfer function with which
the region allowing the brightness conversion is associated
may be inserted as the region information. Furthermore, for
10 example, the region information may include information of
a plurality of regions each having a different allowable level
of the brightness conversion.
[0015]
According to the present technology, the transmission
15 video data is received along with the region information
indicating the region in which the brightness conversion is
allowed, so that the output video data is acquired by performing
the brightness conversion processing on the basis of the region
information. As a result, the feel of brightness intended
20 by the production side can be satisfactorily reproduced.
EFFECTS OF THE INVENTION
[0016]
According to the present technology, the feel of
25 brightness intended by the production side can be
satisfactorily reproduced on the reception side. Note that
the effect described in the present specification is provided
by way of example only and not by way of limitation, where
there may be obtained an additional effect as well.
30
BRIEF DESCRIPTION OF DRAWINGS
7
[0017]
Fig. 1 is a block diagram illustrating an example of
the configuration of a transmission/reception system
according to an embodiment.
5 Fig. 2 is a block diagram illustrating an example of
the configuration of a transmission device included in the
transmission/reception system.
Fig. 3 is a diagram illustrating an example of a display
brightness characteristic of a master monitor.
10 Fig. 4 is a graph illustrating an example of an
opto-electrical transfer function (OETF).
Fig. 5 is a diagram illustrating a top access unit of
a GOP when HEVC is employed as an encoding scheme.
Fig. 6 is a diagram illustrating an access unit other
15 than the top of the GOP when HEVC is employed as the encoding
scheme.
Fig. 7 is a table illustrating an example of the structure
of a level_mapping SEI message.
Fig. 8 is a diagram illustrating details of main
20 information in the example of the structure of the
level_mapping SEI message.
Figs. 9(a) and 9(b) are graphs each illustrating an
example of the opto-electrical transfer function (OETF) with
which a region allowing a brightness conversion is associated
25 in advance.
Fig. 10 is a block diagram illustrating an example of
the configuration of a reception device included in the
transmission/reception system.
Fig. 11 is a graph illustrating an example of an
30 electro-optical transfer function (EOTF).
Fig. 12 is a graph illustrating an example of a display
8
brightness characteristic of a CE monitor.
Fig. 13 is a graph illustrating an example of the display
brightness characteristic of the CE monitor.
Fig. 14 is a graph illustrating an example of a
5 relationship between the electro-optical transfer function
(EOTF) of an HDR electro-optical conversion unit in the
reception device and a plurality of pairs of threshold
information.
Fig. 15 is a table illustrating an example of the
10 structure of the level_mapping SEI message transmitted when
a first transmission method is adopted.
Figs. 16(a) and 16(b) are graphs each illustrating an
example of the opto-electrical transfer function (OETF) with
which a region allowing the brightness conversion is associated
15 in advance when a second transmission method is adopted.
Fig. 17 is a block diagram illustrating an example of
another configuration of the transmission/reception system.
MODES FOR CARRYING OUT THE INVENTION
20 [0018]
Modes for carrying out the invention (hereinafter
referred to as “embodiments”) will now be described. Note
that the description will be provided in the following order.
1. Embodiment
25 2. Variation
[0019]
<1. First embodiment>
[Example of configuration of transmission/reception
system]
30 Fig. 1 illustrates an example of the configuration of
a transmission/reception system 10 according to an embodiment.
9
The transmission/reception system 10 includes a transmission
device 100 and a reception device 200.
[0020]
The transmission device 100 generates a transport stream
5 TS in MPEG2 as a container and transmits the transport stream
TS on a broadcast wave or an Internet packet. The transport
stream TS includes a video stream acquired by encoding
transmission video data that is obtained by application of
a predetermined opto-electrical transfer function to input
10 video data.
[0021]
The input video data is for example video data of a high
dynamic range (HDR) image with a contrast ratio of 0 to 100%
* N (where N is a number larger than 1) exceeding brightness
15 of the white peak in a conventional low dynamic range (LDR)
image. Here, a 100% level is assumed to be a brightness level
corresponding to 100 cd/m2 being a brightness value of white.
[0022]
Region information indicating a region in which a
20 brightness conversion is allowed is inserted into a layer of
the video stream. When a first transmission method is adopted,
a piece of metadata indicating the region in which the
brightness conversion is allowed is inserted into the layer
of the video stream. On the other hand, when a second
25 transmission method is adopted, there is inserted a piece of
information specifying the aforementioned predetermined
opto-electrical transfer function with which the region
allowing the brightness conversion is associated. The region
information will be described in detail later on.
30 [0023]
The reception device 200 receives the transport stream
10
TS transmitted on the broadcast wave or Internet packet from
the transmission device 100. The transport stream TS includes
the video stream including the encoded video data. As
described above, the region information indicating the region
5 in which the brightness conversion is allowed is inserted into
the video stream.
[0024]
The reception device 200 acquires output video data by
applying, for example, an electro-optical transfer function
10 inverse of and corresponding to the aforementioned
predetermined opto-electrical transfer function on a
transmission side to the transmission video data and performing
brightness conversion processing thereon on the basis of the
region information. In this case, the brightness conversion
15 dependent on, for example, the peak brightness of a monitor
is performed only in the region allowing the brightness
conversion.
[0025]
[Example of configuration of transmission device]
20 Fig. 2 illustrates an example of the configuration of
the transmission device 100. The transmission device 100
includes a control unit 101, an HDR camera 102, an HDR
photoelectric conversion unit 103, a video encoder 104, a
system encoder 105 and a transmission unit 106. The control
25 unit 101 includes a central processing unit (CPU) and controls
the operation of each unit in the transmission device 100 on
the basis of a control program stored in a storage not shown.
[0026]
The HDR camera 102 images a subject to output high dynamic
30 range (HDR) video data. The HDR video data has a contrast
ratio of 0 to 100% * N (where N is a number larger than 1)
11
such as 0 to 1000% exceeding brightness of the white peak in
a conventional low dynamic range (LDR) image. Here, a 100%
level corresponds to 100 cd/m2 being the brightness value of
white, for example. Note that “cd/m2” represents “cd/square
5 meter”.
[0027]
A master monitor 103a is a monitor that performs grading
on the HDR video data acquired by the HDR camera 102. The
master monitor 103a has a display brightness level
10 corresponding to the HDR video data or suitable for grading
the HDR video data.
[0028]
Fig. 3 illustrates a display brightness characteristic
of the master monitor 103a. A horizontal axis and a vertical
15 axis of the graph represent an input brightness level and the
display brightness level, respectively. When the input
brightness level equals reference brightness RL, the display
brightness level equals a relative reference level (%) such
as 100% corresponding to 100 cd/m2 being the brightness value
20 of white. Moreover, the display brightness level equals a
relative peak level (%) when the input brightness level equals
peak brightness PL.
[0029]
Note that threshold brightness CL is newly defined in
25 the present embodiment and indicates a boundary between a
region in which the brightness corresponds with brightness
displayed in a monitor (CE monitor) on the side of a receiver
and a region in which the brightness is dependent on the CE
monitor. The display brightness level equals a relative
30 threshold level (%) when the monitor input brightness level
equals the threshold brightness CL.
12
[0030]
Referring back to Fig. 2, the HDR photoelectric
conversion unit 103 applies an opto-electrical transfer
function for an HDR image (HDR OETF curve) to the HDR video
5 data acquired by the HDR camera 102 and acquires transmission
video data V1.
[0031]
Fig. 4 illustrates an example of the opto-electrical
transfer function (OETF). In the graph, a horizontal axis
10 represents the input brightness level as with the horizontal
axis of the graph of the display brightness characteristic
of the master monitor described above(refer to Fig. 3), and
a vertical axis represents a transmission code value. The
transmission code value equals a reference level RP when the
15 input brightness level equals the reference brightness RL.
Moreover, the transmission code value equals a peak level MP
when the input brightness level equals the peak brightness
PL. Furthermore, the transmission code value equals a
threshold level THP when the input brightness level equals
20 the threshold brightness CL.
[0032]
Note that a range of the transmission code value on the
vertical axis corresponds to an input pixel data range of the
video encoder 104 (an encoder input pixel data range). In
25 the case of 10-bit encoding, for example, the range equals
“64” to “940” or “4” to “1019” with use of an extended region.
[0033]
Referring back to Fig. 2, the video encoder 104 encodes
the transmission video data V1 by MPEG4-AVC, MPEG2 video or
30 high efficiency video coding (HEVC), for example, and acquires
encoded video data. The video encoder 104 further uses a stream
13
formatter (not shown) provided in a subsequent stage to
generate a video stream (video elementary stream) containing
the encoded video data.
[0034]
5 At this time, the video encoder 104 inserts into a layer
of the video stream the region information indicating the
region allowing the brightness conversion dependent on the
display side. When the first transmission method is adopted,
the metadata indicating the region in which the brightness
10 conversion is allowed is inserted into the layer of the video
stream. When the second transmission method is adopted, there
is inserted the information specifying the aforementioned
opto-electrical transfer function which is applied by the HDR
photoelectric conversion unit 103 and with which the region
15 allowing the brightness conversion is associated.
[0035]
[Insertion of region information]
The insertion of the region information indicating the
region in which the brightness conversion is allowed will be
20 described in detail.
[When first transmission method is adopted]
First, there will be described the case where the first
transmission method is adopted. A newly defined
level_mapping SEI message is inserted into a part corresponding
25 to “SEIs” of an access unit (AU).
[0036]
Fig. 5 illustrates a top access unit of a group of pictures
(GOP) when HEVC is employed as the encoding scheme. Moreover,
Fig. 6 illustrates an access unit other than the top of the
30 GOP when HEVC is employed as the encoding scheme. When HEVC
is employed as the encoding scheme, an SEI message group
14
“Prefix_SEIs” for decoding is arranged in front of slices in
which pixel data is encoded, and an SEI message group
“Suffix_SEIs” for display is arranged after the slices. As
illustrated in Figs. 5 and 6, the level_mapping SEI message
5 is arranged as the SEI message group “Suffix_SEIs”.
[0037]
Fig. 7 illustrates an example of the structure (Syntax)
of the level_mapping SEI message. Fig. 8 illustrates details
(Semantics) of main information in the example of the structure.
10 A syntax “level_mapping_cancel_flag” is 1-bit flag
information. A value “1” indicates that a message status of
level_mapping up to that point is cancelled. A value “0”
indicates that each element is transmitted to refresh a
previous status therewith.
15 [0038]
An 8-bit field of “coded_data_bit_depth” indicates the
bit length of the encoded data for which 8 to 14 bits are used,
for example. A 16-bit field of “reference_white_level”
indicates the input brightness value of the master monitor
20 103a at its 100%, namely the reference brightness RL. A 16-bit
field of “reference_white_level_code_value” indicates a code
value at the 100% brightness level or a value with the bit
accuracy indicated by “coded_data_bit_depth”, namely the
reference level RP.
25 [0039]
An 8-bit field of “number_of_thresholds” indicates the
number of threshold divisions of display mapping. A 16-bit
field of “compliant_threshold_level” and a 16-bit field of
“compliant_threshold_level_value” exist repeatedly for the
30 number of threshold divisions. The number equals “1” in the
present embodiment.
15
[0040]
The field of “compliant_threshold_level” indicates a
threshold level (percentage) assuming the display mapping or
a level relative to the 100% brightness, namely the threshold
5 brightness CL. The field of
“compliant_threshold_level_value” indicates a code value
transmitting the threshold assuming the display mapping,
namely the threshold level THP. This value is the maximum
value of brightness with which the brightness in CE monitor
10 display assumed by the production side is to correspond, where
a level exceeding the value indicates a region (range) in which
the brightness is allowed to change depending on the display
capability of the CE monitor.
[0041]
15 Note that this definition is provided for a first
threshold. When there exists second and successive
thresholds with the values larger than the first threshold,
such thresholds correspond to information on a plurality of
regions (region division information) having different
20 allowable levels of brightness conversion.
[0042]
An 8-bit field of “peak_percentage” indicates a value
of the maximum brightness level expressed by a ratio with
respect to 100% on the production side. The peak brightness
25 1000 cd/m2 corresponds to “peak_percentage” of 1000%, for
example. A 16-bit field of “peak_percentage_value” indicates
a maximum code value expressing “peak_percentage”, namely the
peak level MP, when data is transmitted with the bit accuracy
indicated by “coded_data_bit_depth”. When
30 “peak_percentage” equals 1000%, for example, the maximum value
“1019” at the time of 10-bit transmission expresses 1000%.
16
[0043]
In the aforementioned level_mapping SEI message, the
information of “compliant_threshold_level” and
“compliant_threshold_level_value” makes up the region
5 information indicating the region in which the brightness
conversion is allowed. As a result, the reception side can
detect the region information indicating the region in which
the brightness conversion is allowed from the level_mapping
SEI message. When the first transmission method is adopted,
10 the region allowing the brightness conversion can be specified
for each picture, scene, program or the like. Note that when
the first transmission method is adopted, it is assumed that
the type of the target opto-electrical transfer function (OETF)
is transmitted in video usability information (VUI) in a NAL
15 unit of a sequence parameter set (SPS).
[0044]
[When second transmission method is adopted]
Next, there will be described the case where the second
transmission method is adopted. As illustrated in Fig. 5,
20 the video usability information (VUI) is inserted in the NAL
unit of the sequence parameter set (SPS) in the top access
unit of the GOP.
[0045]
Among header information encoded by the sequence as the
25 SPS, the VUI specifies timing information of buffer management
as well as a parameter relevant to display control performed
after decoding, and contains information indicating a control
method that realizes image display such as an aspect ratio
of a screen, a color gamut, the type of the opto-electrical
30 transfer function (OETF) and the type of an RGB conversion
matrix.
17
[0046]
As for the type of the OETF, there can be specified “Rec.
ITU-R BT. 709-5” as “Type = 1” and “Rec. ITU-R BT. 2020 for
10 bit” as “Type = 14” under the present conditions. These
5 two types of OETF functions are equal and expressed as follows.
[0047]
V = 1.099 * Lc0.45 − 0.099 for 1 > = Lc > = 0.018
V = 4.500 * Lc for 0.018 > Lc >= 0
The reception side is assumed to convert the
10 aforementioned function into an inverse function thereof as
the EOTF or an inverse OETF.
[0048]
In the present embodiment, the OETF applied by the HDR
photoelectric conversion unit 103 is one of the OETFs with
15 which the region allowing the brightness conversion is
associated in advance. Specifically, each of the following
information is defined as the specification of each OETF, for
example. Here, the information of
“compliant_threshold_level” and
20 “compliant_threshold_level_value” makes up the region
information indicating the region in which the brightness
conversion is allowed. Note that while detailed description
is omitted herein, the content of each information is the same
as the information corresponding to the aforementioned
25 level_mapping SEI message.
[0049]
“coded_data_bit_depth”
“reference_white_level”
“reference_white_level_code_value”
30 “compliant_threshold_level”
“compliant_threshold_level_value”
18
“peak_percentage”
“peak_percentage_value”
[0050]
Figs. 9(a) and 9(b) are graphs each illustrating an
5 example of the opto-electrical transfer function (OETF) with
which the region allowing the brightness conversion is
associated in advance. According to the OETF of a first type
illustrated in Fig. 9(a), the peak brightness equals PL1 and
the corresponding transmission code value equals MP1. In the
10 OETF of the first type, the threshold brightness CL1 and the
threshold level THP1 are defined as the region information
indicating the region in which the brightness conversion is
allowed. Moreover, according to the OETF of a second type
illustrated in Fig. 9(b), the peak brightness equals PL2 and
15 the corresponding transmission code value equals MP2. In the
OETF of the second type, the threshold brightness CL2 and the
threshold level THP2 are defined as the region information
indicating the region in which the brightness conversion is
allowed.
20 [0051]
Then the VUI specifies the OETF applied by the HDR
photoelectric conversion unit 103, namely the OETF with which
the region allowing the brightness conversion is associated
in advance. As a result, the reception side can uniquely detect
25 the region information indicating the region in which the
brightness conversion is allowed from the OETF specified in
the VUI.
[0052]
Note that the electro-optical transfer function (EOTF)
30 is the inverse transform of the opto-electrical transfer
function (OETF) in many cases. Therefore, the region
19
information indicating the region allowing the brightness
conversion (such as the information of
“compliant_threshold_level” and
“compliant_threshold_level_value”) may be defined as the
5 specification of the OETF to be able to represent the display
side.
[0053]
Referring back to Fig. 2, the system encoder 105
generates the transport stream TS including the video stream
10 VS generated by the video encoder 104. The transmission unit
106 then transmits the transport stream TS on the broadcast
wave or Internet packet to the reception device 200.
[0054]
The operation of the transmission device 100 illustrated
15 in Fig. 2 will be described briefly. The HDR video data
acquired upon imaging by the HDR camera 102 is supplied to
the HDR photoelectric conversion unit 103. The HDR video data
acquired by the HDR camera 102 is subjected to grading by using
the master monitor 103a. The HDR photoelectric conversion
20 unit 103 applies the opto-electrical transfer function for
an HDR image (the LDR OETF curve) to the HDR video data and
acquires the transmission video data V1. The transmission
video data V1 is supplied to the video encoder 104.
[0055]
25 The video encoder 104 encodes the transmission video
data V1 by MPEG4-AVC, MPEG2 video or HEVC, for example, and
acquires the encoded video data. The video encoder 104 further
uses the stream formatter (not shown) provided in the
subsequent stage to generate the video stream (video elementary
30 stream) VS containing the encoded video data.
[0056]
20
At this time, the video encoder 104 inserts into a layer
of the video stream the region information indicating the
region in which the brightness conversion is allowed. When
the first transmission method is adopted, as described above,
5 the metadata indicating the region in which the brightness
conversion is allowed is inserted into the layer of the video
stream. Moreover, when the second transmission method is
adopted, there is inserted the information specifying the
aforementioned opto-electrical transfer function which is
10 applied by the HDR photoelectric conversion unit 103 and with
which the region allowing the brightness conversion is
associated, as described above.
[0057]
The video stream VS generated by the video encoder 104
15 is supplied to the system encoder 105. The system encoder
105 generates the MPEG2 transport stream TS containing the
video stream. The transport stream TS is transmitted on the
broadcast wave or Internet packet by the transmission unit
106 to the reception device 200.
20 [0058]
[Example of configuration of reception device]
Fig. 10 illustrates an example of the configuration of
the reception device 200. The reception device 200 includes
a control unit 201, a reception unit 202, a system decoder
25 203, a video decoder 204, an HDR electro-optical conversion
unit 205, a display mapping unit 206, and a CE monitor 207.
The control unit 201 includes a central processing unit (CPU)
and controls the operation of each unit in the reception device
200 on the basis of a control program stored in a storage not
30 shown.
[0059]
21
The reception unit 202 receives the transport stream
TS transmitted on the broadcast wave or Internet packet from
the transmission device 100. The system decoder 203 extracts
the video stream (elementary stream) VS from the transport
5 stream TS. Moreover, the system decoder 203 extracts various
pieces of information inserted in the layer of the container
(transport stream) and transmits the information to the control
unit 201.
[0060]
10 The video decoder 204 decodes the video stream VS
extracted by the system decoder 203 and outputs the
transmission video data V1. Moreover, the video decoder 204
extracts and transmits to the control unit 201 the parameter
set and the SEI message inserted in each access unit making
15 up the video stream VS.
[0061]
According to the type specification of the OETF in the
video usability information (VUI) in the SPS, the control unit
201 recognizes the opto-electrical transfer function (OETF)
20 applied on the transmission side and sets, for example, the
electro-optical transfer function (EOTF) corresponding to and
having an inverse characteristic of the OETF to the HDR
electro-optical conversion unit 205.
[0062]
25 Moreover, when the aforementioned second transmission
method is adopted, the control unit 201 can uniquely detect
the region information indicating the region allowing the
brightness conversion (such as the information of
“compliant_threshold_level” and
30 “compliant_threshold_level_value”) from the OETF specified
in the VUI.
22
[0063]
Moreover, when the aforementioned first transmission
method is adopted, the aforementioned level_mapping SEI
message is included as one of the SEI messages extracted by
5 the video decoder 204 and transmitted to the control unit 201.
The control unit 201 can acquire, from the level_mapping SEI
message, the region information indicating the region in which
the brightness conversion is allowed (the information of
“compliant_threshold_level” and
10 “compliant_threshold_level_value”).
[0064]
The HDR electro-optical conversion unit 205 applies,
to the transmission video data V1 output from the video decoder
204, the electro-optical transfer function (EOTF) or the like
15 corresponding to and having the inverse characteristic of the
opto-electrical transfer function (OETF) used in the HDR
photoelectric conversion unit 103 of the transmission device
100, and acquires output video data used to display an HDR
image.
20 [0065]
Fig. 11 illustrates an example of the electro-optical
transfer function (EOTF). A horizontal axis of the graph
represents the transmission code value corresponding to the
vertical axis of the graph in Fig. 4. A vertical axis
25 represents an output brightness level (display brightness
level) corresponding to the horizontal axis of the graph in
Fig. 4. A solid line a in the graph represents an EOTF curve.
The output brightness level equals PL when the transmission
code value equals the peak level MP. Moreover, the output
30 brightness level equals CL when the transmission code value
equals the threshold level THP.
23
[0066]
Here, when the maximum brightness display capability
of the CE monitor 207 is higher than the maximum brightness
PL assumed on the master monitor 103a, the output brightness
5 level corresponding to a value of the transmission code value
larger than the threshold level THP is processed by the display
mapping unit 206 and allocated to a range up to a maximum display
brightness level DP1 of the CE monitor 207 (high brightness
processing). A two-dot chain line b in the graph represents
10 an example of brightness conversion processing performed in
that case.
[0067]
On the other hand, when the maximum brightness display
capability of the CE monitor 207 is lower than the maximum
15 brightness PL assumed on the master monitor 103a, the output
brightness level corresponding to a value of the transmission
code value larger than the threshold level THP is processed
by the display mapping unit 206 and allocated to a range up
to a maximum display brightness level DP2 of the CE monitor
20 207 (low brightness processing). A dot and dash line c in
the graph represents an example of brightness conversion
processing performed in that case.
[0068]
Referring back to Fig. 10, the display mapping unit 206
25 converts a level exceeding the brightness CL among the output
brightness levels of the HDR electro-optical conversion unit
205 according to the maximum brightness display capability
of the CE monitor 207, as described above. In this case, the
brightness does not depend on the CE monitor 207 when the
30 transmission code value equals the threshold level THP or lower,
namely the output brightness level equals CL or lower, so that
24
the brightness at the reception level is reproduced faithfully
and that texture or the like is expressed correctly in
accordance with the intention on the production side. The
CE monitor 207 displays the HDR image on the basis of the output
5 video data from the display mapping unit 206.
[0069]
When the maximum brightness display capability DP of
the CE monitor 207 exceeds the maximum brightness PL assumed
on the master monitor 103a, namely DP > PL, the display mapping
10 processing unit 206 performs the high brightness processing
that allocates the level exceeding the brightness CL to the
range up to the peak brightness DP by using a predetermined
algorithm.
[0070]
15 Fig. 12 illustrates the display brightness
characteristic of the CE monitor 207 in that case. The
characteristic includes the brightness conversion
characteristic of the display mapping unit 206. A horizontal
axis and a vertical axis of the graph represent the input
20 brightness level and the display brightness level,
respectively. The display brightness level equals a relative
threshold level (%) when the input brightness level equals
the threshold brightness CL. Moreover, the display
brightness level equals a relative peak level (%) of the CE
25 monitor 207 when the input brightness level equals the peak
brightness PL.
[0071]
Moreover, when the maximum brightness display
capability DP of the CE monitor 207 is lower than the maximum
30 brightness PL assumed on the master monitor 103a, namely DP
< PL, the display mapping processing unit 206 performs the
25
low brightness processing that allocates the level exceeding
the brightness CL to the range up to the peak brightness DP
by using a predetermined algorithm.
[0072]
5 Fig. 13 illustrates the display brightness
characteristic of the CE monitor 207 in that case. The
characteristic includes the brightness conversion
characteristic of the display mapping unit 206. A horizontal
axis and a vertical axis of the graph represent an input
10 brightness level and the display brightness level,
respectively. The display brightness level equals a relative
threshold level (%) when the input brightness level equals
the threshold brightness CL. Moreover, the display
brightness level equals a relative peak level (%) of the CE
15 monitor 207 when the input brightness level equals the peak
brightness PL.
[0073]
Moreover, when the maximum brightness display
capability DP of the CE monitor 207 is the same as the maximum
20 brightness PL assumed on the master monitor 103a, namely DP
= PL, the display mapping processing unit 206 outputs the data
as is without performing the brightness conversion processing
on the level exceeding the brightness CL. In this case, the
brightness on the production side all across the range up to
25 the peak level of the master monitor 103a is allocated as is
to the display on the CE monitor 207.
[0074]
The operation of the reception device 200 illustrated
in Fig. 10 will be described briefly. The reception unit 202
30 receives the transport stream TS transmitted on the broadcast
wave or Internet packet from the transmission device 100. The
26
transport stream TS is supplied to the system decoder 203.
The system decoder 203 extracts the video stream (elementary
stream) VS from the transport stream TS.
[0075]
5 The video stream VS extracted by the system decoder 203
is supplied to the video decoder 204. The video decoder 204
decodes the video stream VS extracted by the system decoder
203 and acquires the transmission video data V1. Moreover,
the video decoder 204 extracts and transmits to the control
10 unit 201 the parameter set and the SEI message inserted in
each access unit making up the video stream VS.
[0076]
When the first transmission method is adopted, the
control unit 201 acquires from the level_mapping SEI message
15 the region information indicating the region in which the
brightness conversion is allowed (the information of
“compliant_threshold_level” and
“compliant_threshold_level_value”). Moreover, when the
second transmission method is adopted, the control unit 201
20 uniquely detects the region information indicating the region
allowing the brightness conversion (such as the information
of “compliant_threshold_level” and
“compliant_threshold_level_value”) from the OETF specified
in the VUI.
25 [0077]
The transmission video data V1 acquired by the video
decoder 204 is supplied to the HDR electro-optical conversion
unit 205. The HDR electro-optical conversion unit 205 applies,
to the transmission video data V1, the electro-optical transfer
30 function (EOTF) or the like corresponding to and having the
inverse characteristic of the opto-electrical transfer
27
function (OETF) used in the HDR photoelectric conversion unit
103 of the transmission device 100, and acquires the output
video data used to display the HDR image. The output video
data is supplied to the display mapping unit 206.
5 [0078]
Among the output brightness levels of the HDR
electro-optical conversion unit 205, the display mapping unit
206 converts the level exceeding the brightness CL according
to the maximum brightness display capability of the CE monitor
10 207. The output video data from the display mapping unit 206
is supplied to the CE monitor 207. The HDR image is displayed
on the CE monitor 207.
[0079]
As described above, according to the
15 transmission/reception system 10 illustrated in Fig. 1, the
transmission video data V1 acquired by performing the
photoelectric conversion on the HDR video data is transmitted
along with the region information indicating the region in
which the brightness conversion is allowed (the information
20 of “compliant_threshold_level” and
“compliant_threshold_level_value”). Therefore, for
example, the brightness conversion according to the display
brightness capability of the CE monitor 207 is performed only
in the region in which the brightness conversion is allowed
25 on the reception side, whereby the feel of brightness intended
by the production side can be reproduced satisfactorily.
[0080]
<2. Variation>
Note that when the first transmission method is adopted
30 in the aforementioned embodiment, the newly-defined
level_mapping SEI message (refer to Fig. 7) is inserted into
28
the part corresponding to “SEIs” of the access unit (AU). While
the aforementioned embodiment illustrates the example of
transmitting only one piece of the information (threshold
information) of “compliant_threshold_level” and
5 “compliant_threshold_level_value” in the level_mapping SEI
message, a plurality of pieces of the threshold information
can also be transmitted.
[0081]
Fig. 14 illustrates an example of a relationship between
10 the electro-optical transfer function (EOTF) of the HDR
electro-optical conversion unit 205 in the reception device
200 and the plurality of pairs of the threshold information.
This example illustrates a case where two pieces of the
threshold information are transmitted. A solid line a in the
15 graph represents an EOTF curve. The output brightness level
equals PL when the transmission code value equals the peak
level MP.
[0082]
Moreover, the output brightness levels equal CL0 and
20 CL1 when the transmission code values equal threshold levels
THP0 and THP1, respectively. Here, the two pairs of the
threshold information (CL0, THP0) and (CL1, THP1) are provided
by the level_mapping SEI message. In this case, a region with
the transmission code value from 0 to THP0 is a region in which
25 the brightness conversion is not allowed and in which the
display brightness level matches when any type of CE monitor
is used. Accordingly, as for the output brightness level of
this region, the display mapping unit 206 does not perform
the brightness conversion processing.
30 [0083]
A region with the transmission code value from THP0 to
29
MP is a region in which the brightness conversion is allowed.
Accordingly, as for the output brightness level of this region,
the display mapping unit 206 performs the brightness conversion
processing according to the maximum display capability of the
5 CE monitor 207, for example. Note however that the allowable
level of brightness conversion varies between a region from
THP0 to THP1 and a region from THP1 to MP. In the region from
THP0 to THP1, for example, the brightness conversion can be
performed in a range in which texture is saved. Moreover,
10 the brightness conversion can be performed in the region from
THP1 to MP without any restrictions.
[0084]
Accordingly, the transmission of the plurality of the
threshold information can allow the reception side to have
15 variations in the display mapping processing, whereby the feel
of an image on the production side can be reproduced more
flexibly on various CE monitors 207.
[0085]
When the aforementioned first transmission method is
20 adopted, the plurality of the threshold information can be
transmitted while being inserted into the level_mapping SEI
message. When the second transmission method is adopted, one
piece of the threshold information to be the basis of the
specification of the opto-electrical transfer function (OETF)
25 specified in the VUI is transmitted, whereas the other
threshold information can be transmitted by using the
level_mapping SEI message, for example.
[0086]
Moreover, the aforementioned embodiment illustrates
30 the example of defining and using the threshold brightness
CL in addition to the reference brightness RL. However, the
30
reference brightness RL can be synonymous with the threshold
brightness CL to be used. In this case, the information of
the reference brightness RL and the reference level RP (refer
to Fig. 4) is also transmitted as the threshold information.
5 The information of the threshold brightness CL and the
threshold level THP need not be transmitted in this case. In
that case, the reference brightness RL and the reference level
RP are not necessarily limited to the 100% brightness, but
another percentage can be defined as a level that matches
10 between the transmission and reception sides.
[0087]
Fig. 15 illustrates an example of the structure (Syntax)
of the level_mapping SEI message that is transmitted while
being inserted into the part corresponding to “SEIs” of the
15 access unit (AU), when the first transmission method is adopted.
Details of the main information in the example of the structure
(Semantics) are similar to those of the level_mapping SEI
message illustrated in Fig. 7. Note however that the 16-bit
field of “reference_white_level” indicates a brightness value
20 of the threshold level assuming display mapping as well as
the input brightness value of the master monitor 103a at its
100%, namely the reference brightness RL.
[0088]
Figs. 16(a) and 16(b) are graphs each illustrating an
25 example of the opto-electrical transfer function (OETF) with
which the region allowing the brightness conversion is
associated in advance when the second transmission method is
adopted. According to the OETF of a first type illustrated
in Fig. 16(a), the peak brightness equals PL1 and the
30 corresponding transmission code value equals MP1. In the OETF
of the first type, reference brightness RL1 and a reference
31
level RP1 are defined as the region information indicating
the region in which the brightness conversion is allowed.
Moreover, according to the OETF of a second type illustrated
in Fig. 16(b), the peak brightness equals PL2 and the
5 corresponding transmission code value equals MP2. In the OETF
of the second type, reference brightness RL2 and a reference
level RP2 are defined as the region information indicating
the region in which the brightness conversion is allowed.
[0089]
10 Moreover, the aforementioned embodiment illustrates
the example in which the reception device 200 performs the
electro-optical conversion processing in the HDR
electro-optical conversion unit 205 as well as the brightness
conversion processing in the display mapping unit 206 according
15 to the maximum brightness display capability of the CE monitor
207. However, the brightness conversion characteristic may
be reflected in the electro-optical transfer function (EOTF)
to be able to perform the electro-optical conversion processing
and the brightness conversion processing at the same time
20 solely by the HDR electro-optical conversion unit 205.
[0090]
Furthermore, while the aforementioned embodiment
illustrates the transmission/reception system 10 including
the transmission device 100 and the receiver 200, the
25 configuration of the transmission/reception system to which
the present technology can be applied is not limited to the
aforementioned configuration. As illustrated in Fig. 17, for
example, the part corresponding to the television receiver
200 may be made up of a set top box 200A and a monitor 200B
30 connected via a digital interface such as a high-definition
multimedia interface (HDMI). Note that “HDMI” is a registered
32
trademark.
[0091]
In this case, the set top box 200A in performing the
display mapping processing can determine the maximum
5 brightness level of the monitor 200B on the basis of information
acquired from EDID of the monitor 200B via the HDMI.
Alternatively, when the monitor 200B performs the display
mapping processing, the information including the
level_mapping SEI message, the type of the EOTF and the VUI
10 can be defined in meta-information such as a “vender specific
info frame” to be shared between the set top box 200A and the
monitor 200B.
[0092]
Moreover, the aforementioned embodiment illustrates
15 the example in which the container is the transport stream
(MPEG-2 TS). In the present technology, however, the
transport is not limited to TS, but another packet such as
an ISOBMFF or MMT can be adopted to realize the layer of the
video by the same method. The present technology can therefore
20 be applied similarly to a system configured to distribute data
to a reception terminal by using a network such as the Internet.
Distribution on the Internet is often performed in a MP4
container or another format. That is, the container
corresponds to the containers of various formats such as the
25 transport stream adopted in a digital broadcasting standard
(MPEG-2 TS) and MP4 used in the Internet distribution.
[0093]
The present technology can also have the following
configuration.
30 (1) A transmission device including:
a processing unit that acquires transmission video data
33
by applying a predetermined opto-electrical transfer function
to input video data; and
a transmission unit that transmits the transmission
video data along with region information indicating a region
5 in which a brightness conversion is allowed.
(2) The transmission device according to (1), further
including an information insertion unit that inserts the region
information into a layer of a video stream, wherein
the transmission unit transmits the video stream
10 acquired by encoding the transmission video data.
(3) The transmission device according to (2), wherein
the information insertion unit inserts metadata as the
region information, the metadata indicating the region in which
the brightness conversion is allowed.
15 (4) The transmission device according to (2), wherein
the information insertion unit inserts, as the region
information, a piece of information specifying the
predetermined opto-electrical transfer function with which
the region allowing the brightness conversion is associated.
20 (5) The transmission device according to any of (1) to
(4), wherein
the region information includes information of a
plurality of regions each having a different allowable level
of the brightness conversion.
25 (6) A transmission method including:
a processing step of acquiring transmission video data
by applying a predetermined opto-electrical transfer function
to input video data; and
a transmission step of using a transmission unit and
30 transmitting the transmission video data along with region
information indicating a region in which a brightness
34
conversion is allowed.
(7) A reception device including:
a reception unit that receives transmission video data
acquired by applying a predetermined opto-electrical transfer
5 function to input video data along with region information
indicating a region in which a brightness conversion is
allowed; and
a processing unit that applies an electro-optical
transfer function corresponding to the predetermined
10 opto-electrical transfer function to the transmission video
data and acquires output video data by performing brightness
conversion processing on the basis of the region information.
(8) The reception device according to (7), wherein
the reception unit receives a video stream acquired by
15 encoding the transmission video data, and
the region information is inserted into a layer of the
video stream.
(9) The reception device according to (8), wherein
metadata indicating the region in which the brightness
20 conversion is allowed is inserted as the region information.
(10) The reception device according to (8), wherein
a piece of information specifying the predetermined
opto-electrical transfer function with which the region
allowing the brightness conversion is associated is inserted
25 as the region information.
(11) The reception device according to any of (7) to
(10), wherein
the region information includes information of a
plurality of regions each having a different allowable level
30 of the brightness conversion.
(12) A reception method including:
35
a reception step of using a reception unit and receiving
transmission video data acquired by applying a predetermined
opto-electrical transfer function to input video data along
with region information indicating a region in which a
5 brightness conversion is allowed; and
a processing step of applying an electro-optical
transfer function corresponding to the predetermined
opto-electrical transfer function to the transmission video
data and acquiring output video data by performing brightness
10 conversion processing on the basis of the region information.
[0094]
A main characteristic of the present technology is that
the transmission video data acquired by performing the
photoelectric conversion on the HDR video data is transmitted
15 along with the region information indicating the region in
which the brightness conversion is allowed, whereby the
reception side performs the brightness conversion only in the
region in which the brightness conversion is allowed to be
able to satisfactorily reproduce the feel of brightness
20 intended by the production side (refer to Figs. 4 and 7).
REFERENCE SIGNS LIST
[0095]
10, 10A Transmission/reception system
25 100 Transmission device
101 Control unit
102 HDR camera
103 HDR photoelectric conversion unit
103a Master monitor
30 104 Video encoder
105 System encoder
36
106 Transmission unit
200 Reception device
200A Set up box
200B Monitor
5 201 Control unit
202 Reception unit
203 System decoder
204 Video decoder
205 HDR electro-optical conversion unit
10 206 Display mapping unit
207 CE monitor
37
CLAIMS
1. A transmission device comprising:
a processing unit that acquires transmission video data
5 by applying a predetermined opto-electrical transfer function
to input video data; and
a transmission unit that transmits the transmission
video data along with region information indicating a region
in which a brightness conversion is allowed.
10
2. The transmission device according to claim 1, further
comprising an information insertion unit that inserts the
region information into a layer of a video stream, wherein
the transmission unit transmits the video stream
15 acquired by encoding the transmission video data.
3. The transmission device according to claim 2, wherein
the information insertion unit inserts metadata as the
region information, the metadata indicating the region in which
20 the brightness conversion is allowed.
4. The transmission device according to claim 2, wherein
the information insertion unit inserts, as the region
information, a piece of information specifying the
25 predetermined opto-electrical transfer function with which
the region allowing the brightness conversion is associated.
5. The transmission device according to claim 1, wherein
the region information includes information of a
30 plurality of regions each having a different allowable level
of the brightness conversion.
38
6. A transmission method comprising:
a processing step of acquiring transmission video data
by applying a predetermined opto-electrical transfer function
5 to input video data; and
a transmission step of using a transmission unit and
transmitting the transmission video data along with region
information indicating a region in which a brightness
conversion is allowed.
10
7. A reception device comprising:
a reception unit that receives transmission video data
acquired by applying a predetermined opto-electrical transfer
function to input video data along with region information
15 indicating a region in which a brightness conversion is
allowed; and
a processing unit that applies an electro-optical
transfer function corresponding to the predetermined
opto-electrical transfer function to the transmission video
20 data and acquires output video data by performing brightness
conversion processing on the basis of the region information.
8. The reception device according to claim 7, wherein
the reception unit receives a video stream acquired by
25 encoding the transmission video data, and
the region information is inserted into a layer of the
video stream.
9. The reception device according to claim 8, wherein
30 metadata indicating the region in which the brightness
conversion is allowed is inserted as the region information.
39
10. The reception device according to claim 8, wherein
a piece of information specifying the predetermined
opto-electrical transfer function with which the region
5 allowing the brightness conversion is associated is inserted
as the region information.
11. The reception device according to claim 7, wherein
the region information includes information of a
10 plurality of regions each having a different allowable level
of the brightness conversion.
12. A reception method comprising:
a reception step of using a reception unit and receiving
15 transmission video data acquired by applying a predetermined
opto-electrical transfer function to input video data along
with region information indicating a region in which a
brightness conversion is allowed; and
a processing step of applying an electro-optical
20 transfer function corresponding to the predetermined
opto-electrical transfer function to the transmission video
data and acquiring output video data by performing brightness
conversion processing on the basis of the region information.