OA19660A - Source color volume information messaging. - Google Patents

Abstract

Methods are described to communicate source color volume information in a coded bitstream using SEI messaging. Such data include at least the minimum, maximum, and average luminance values in the source data plus optional data that may include the color volume x and y chromaticity coordinates for the input color primaries (e.g., red, green, and blue) of the source data, and the color x and y chromaticity coordinates for the color primaries corresponding to the minimum, average, and maximum luminance values in the source data. Messaging data signaling an active region in each picture may also be included.

Description

SOURCE COLOR VOLUME INFORMATION MESSAGING

CROSS-REFERENCE TO RELATED APPLICATIONS

This application daims the benefit of priority to U.S. Provisional Patent Application No. 62/427,677, filed November 29, 2016, and to U.S. Provisional Patent Application No. 62/404,302, filed October 5, 2016, both of which are hereby incorporated by reference in their entirety.

TECHNOLOGY

The présent invention relates generally to images. More particularly, an embodiment of the présent invention relates to communicating and processing source color volume information.

BACKGROUND

Recommendation ITU-T H.265 [1] (also known as HEVC) for “coding of moving video,” in Annex D, Supplémentai enhancement information (SEI), and Annex E, “Video usability information” (VUI), describes the syntax for providing supplémentai SEI and VUI information in a coded bitstream to enable a décoder to better map the decoded samples into a display.

In parallel with the MPEG/ITU standardization processes, the society of motion picture and télévision engineers (SMPTE) has also defined a number of Recommendations related to communicating metadata related to the color volume information for both the source video and a targeted display. For example, the SMPTE ST 2094 suite of documents (e.g., [5] and [6]) define metadata for use in color volume transforms of video content. These metadata may vary scene-by-scene or frame-by-frame. For example, such metadata may assist a décoder to présent high-dynamic range (HDR) and wide color gamut (WCG) data on a display having a smaller color volume than that of the mastering display used for mastering the source images.

As used herein, the term “metadata” relates to any auxiliary information that is transmitted as part of the coded bitstream and assists a décoder to render a decoded image. Such metadata may include, but are not limited to, color space or gamut information, prédiction parameters, reference display parameters, and auxiliary signal parameters, as those described herein.

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While Annexes D and E of H.265 support a number of color volume related metadata, they do not carry ail the required metadata for the most efficient display management of HDR content. In July of 2016, in the joint collaborative team on video coding (JCT-VC) meeting in Geneva, three proposais [2-4] were submitted on how to describe content color volume information using SEI or VUI messaging. Some of these proposais were influenced by SMPTE ST. 2094 [5], but they were considerably different in scope.

In [2], a content-SEI message is proposed to signal content color gamut in 2D, which describes the actual color distribution of the video content. In VUI, the variable colour_primaries is used to indicate the container color gamut instead of true source color gamut [1], In [3], multiple primary expressions and spatial régions are proposed to be associated with the identified source characteristics. In [4], a content color volume SEI message is proposed to indicate the color volume occupied by the content. It uses an (x, y, Y) description of the color coordinates and has slices of luminance Y with associated polygons for each slice. These proposais hâve multiple shortcomings such as: provide information of little use to most display manufacturers, may add significant overhead, and may require too much computational overhead to generate. To improve existing coding and decoding schemes, as appreciated by the inventors here, improved techniques for generating and communicating source color volume information are required.

The approaches described in this section are approaches that could be pursued, but not necessarily approaches that hâve been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to hâve been recognized in any prior art on the basis of this section, unless otherwise indicated.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the présent invention is illustrated by way of example, and not in way by limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar éléments and in which:

FIG. 1 depicts an example process for a video delivery pipeline according to an embodiment of this invention;

FIG. 2 depicts an example of a “largest” possible color volume plot for a video container format;

FIG. 3 A depicts an example of source content gamut within the container color volume;

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FIG. 3B and FIG. 3C depict examples of 2D slices of the container and source color volume at spécifie luminance (F) values; and

FIG. 4 depicts an example process for extracting source color volume information from SEI messaging according to an embodiment of this invention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Techniques for communicating source color volume information using SEI messaging are described herein. In the following description, for the purposes of explanation, numerous spécifie details are set forth in order to provide a thorough understanding of the présent invention. It will be apparent, however, that the présent invention may be practiced without these spécifie details. In other instances, well-known structures and devices are not described in exhaustive detail, in order to avoid unnecessarily occluding, obscuring, or obfiiscating the présent invention.

OVERVIEW

Example embodiments described herein relate to techniques for communicating source color volume information using SEI messaging. In a décoder, a processor for extracting SEI messaging receives a source color volume identification messaging variable identifying the presence of source color volume information in an input bitstream. The processor receives a first messaging variable as part of the source color volume information. If the first messaging variable matches a first predetermined value, then for one or more color primaries, it generates x and y chromaticity coordinates for the one or more color primaries based on the source color volume information in the input bitstream. It generates a minimum, a maximum, and an average luminance value based on the source color volume information in the input bitstream. The processor receives a second messaging variable as part of the source color volume information, and if the second messaging variable matches a second predetermined value, then for one or more color primaries, it generates x and y chromaticity coordinates for the one or more color primaries corresponding to the minimum, maximum, and average luminance values based on the source color volume information.

Examples of Source Color Volume Messaging

FIG. 1 depicts an example process of a video delivery pipeline (100) showing various stages from video capture to video content display. A sequence of video frames (102) is captured or

-3 19660 generated using image génération block (105). Video frames (102) may be digitally captured (e.g. by a digital caméra) or generated by a computer (e.g. using computer animation) to provide video data (107). Altematively, video frames (102) may be captured on film by a film caméra. The film, after appropriate editing (not shown), is converted to a digital format to provide video data (107).

The video data (107) is then provided to a processor at block (110) for post-production editing. Post-production editing (110) may include adjusting or modifying colors or brightness in particular areas of an image to enhance the image quality or achieve a particular appearance for the image in accordance with the video creator's créative intent. This is sometimes called “color timing” or “color grading.” Other editing (e.g. scene sélection and sequencing, image cropping, addition of computer-generated visual spécial effects, etc.) may be performed at block (110) to yield a final version (112) of the production for distribution. During post-production editing (110), video images are viewed on a reference display (125) (also to be referred to as the “targeted display” since the studio optimizes the video for ).

In some embodiments, before video coding (120), video content may be analyzed to extract source-color-volume metadata (119), for example as defined in SMPTE ST 2094-1 [5], or as will be defined later in this invention. Such metadata may also define the characteristics of the targeted display (e.g., reference display (125)) and color remapping information so that a downstream receiver can render the decoded data in the best possible way.

Following post-production (110) and source-color volume analysis (115), video data of the final production (117) and associated metadata (119) may be delivered in an appropriate color format (e.g., 10-bit YCbCr in 4:2:0, ICtCp, and the like) to encoding block (120) for delivering downstream to decoding and playback devices such as télévision sets, set-top boxes, movie theaters, and the like. In some embodiments, coding block (120) may include audio and video encoders, such as those defined by ATSC, DVB, DVD, Blu-Ray, and other delivery formats, to generate coded bit stream (122). Coded bitstream (122) may be represented by a single layer video coded bitstream or by a multi-layer bitstream. For example, in a multi-layer bitstream, signal (122) may include a base layer (say, an SDR layer or a 10-bit HDR (HDR10) layer) and an enhancement layer, which when combined with the base layer yields a HDR bitstream with higher dynamic range than the base layer alone (e.g., a 12-bit HDR signal). Signal (122), the output bitstream from the encoder (120) may also include metadata (119) and additional coding-related metadata, such as prédiction parameters and other data to assist a décoder to better reconstruct an HDR signal.

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In a receiver, the coded bit stream (122) is decoded by decoding unit (130) to generate a decoded signal (132) and associated metadata (119). The receiver (or target) display (150) may hâve completely different characteristics than the reference (or targeted) display (125). For example, without limitation, the reference display (125) may be a 1,000 nits display while the receiver display may be a 500 nits display. In that case, a display management module (140) may be used to map the dynamic range of decoded signal (132) to the characteristics of the receiver display (150) by generating display-mapped signal (142). As used herein, the tenu “display management” dénotés the processing (e.g., tone and gamut mapping) required to map an input video signal of a first dynamic range (e.g., 1000 nits) to a display of a second dynamic range (e.g., 500 nits). Display management unit (140) may take into considération metadata (119) to improve the quality of the output video on display (150). For example, as shown in [7], information about the luminance range of the targeted (or reference) display (e.g., 125) and the source data may be used on a receiver to better map the dynamic range of the video content into the receiver display (e.g., 150).

Color Volume Information

FIG. 2 depicts an example of the “largest” possible color volume of a pre-defmed container format (e.g., BT. 2020) (also to be referred as the “container color volume”). Such a volume can be constructed by two-dimensional (2D) color-gamut primaries, the white point chromaticity (e.g., D65), a maximum luminance value (e.g., Lmax = 4,000 nits), and a minimum luminance value (e.g., 0.005 nits). Such a plot indicates the largest possible color volume boundary for ail the colors within the source video content.

In practice, as depicted by the darker “cloud” (305) in FIG. 3 A or the darker régions (305) in FIG. 3B and FIG. 3C, the source-color volume of the source content (e.g., 112) for a particular frame, or even within a whole scene, may be significantly smaller than the largest possible color volume (310). Because the actual color volume (305) has very irregular shape, transmitting such source color volume information for each frame or the whole scene requires lots of information. For example, in an embodiment, one may signal the color gamut information for multiple luminance values (say, at 0.1, 1, 10, and the like). The question then becomes: how many and which are the most important luminance values? One also needs to take into considération not only the required overhead of such information on the coded bit stream, but also the complexity of generating such content on an encoder and/or reconstructing color volume information on the décoder.

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While communicating minimum and maximum luminance values in the source content is important, as appreciated by the inventors, communicating the average luminance (or midpoint luminance) is also valuable to a receiver. These three values together can help generate a reasonable tone curve for display mapping. In this disclosure, it is proposed to signal the following metadata to describe source color volume: a) the largest 2D color gamut the source occupied (e.g., the source color volume); b) the maximum, minimum and average luminance of the source; and c) optionally, the sliced (2D) color gamut for those three luminance values (e.g., see FIG. 3B and 3C). It is assumed that the white points of the container primary and the source content primary should be the same, so there is no reason to retransmit such information. This information may be updated as needed, e.g., on a per-frame or a per-scene basis. FIG. 3B and FIG. 3C depict examples of 2D slices of the source color volume (305) and the container color volume (310) at spécifie luminance (F) values. In FIG. 3B, the 2D slice is at Y = 84 nits, and in FIG. 3C, the 2D slice is at Y = 246 nits. The chromaticity (rgb) triangles, surrounding source color volume (305) and within the container RGB space, are provided for illustration purposes only. An encoder may select to define and communicate to a receiver smaller or bigger such areas.

Table 1 depicts an example of source-color volume SEI messaging according to an embodiment that follows the nomenclature and syntax of the H.265 spécification. The description of color primaries follows the définition of CIE 1931 (x,y) color chromaticity coordinates for color primaries as defined in ISO 11664-1 (see also ISO 11664-3 and CIE 15), and uses red, green, and blue color primaries. Other types of color primaries, such four, five, or six, or other polygon-based color primary présentation can also be used. For the largest actual color gamut within the source content, in an embodiment, without limitation, the syntax is similar to the définition of the colour_primaries parameter (or variable) defined in Section E.3.1, for Table E.3, of the H.265 spécification. It is believed that current source content can reach the P3 color space, but it will take some time to reach BT. 2020/2010 color (“DCI-P3” is defined in SMPTE EG 432-1 and SMPTE RP 431-2). Therefore, in those cases where the source color gamut is smaller or equal to P3, or equal to BT. 2020/2010 color primaries, Table E.3 can be used; however, for sources whose color gamut is larger than P3 but smaller than BT. 2020/2010, explicit signalling of color gamut might be required.

Luminance values are specified using their absolute value in nits (cd/m²}. Altematively, to save bits, luminance values may also be encoded using a non-linear représentation, e.g., as values encoded according to the inverse EOTF of SMPTE ST 2084. The color gamut

-619660 information corresponding to the max, min, and average (mid) luminance values is made optional, allowing applications to reduce the metadata overhead as desired.

Notes: in a preferred embodiment, 1) the source color volume metadata should describe the color volume of the source in its original form, before any luma or chroma pre-processing. For example, it should describe source color volume before any chroma subsampling process (e.g., from 4:4:4 to 4:2:0) or bit depth conversion process (e.g., from 12 b to 10 b), because chroma subsampling or bit depth conversion will modify the color volume information. 2) The source color gamut is typically different from the container color primaries, which is indicated in Annex E (e.g., Table E.3) of H.265. 3) The source color volume is typically different from the mastering display color volume, which may be indicated by the mastering display color volume SEI messages.

In an example embodiment, parameters (or variables) and coding semantics in Table 1 may be described as follows:

source_colour_volume_id contains an identifying number that may be used to identify the purpose of the source color volume. The value of source_colour_volume_id shall be in the range of 0 to 2 - 2, inclusive. Values of source_colour_volume_id from 0 to 255 and from 512 to 2 - 1 may be used as determined by the application. Values of source_colour_volume_id from 256 to 511, inclusive, and from 2³¹ to 2³² - 2, inclusive, are reserved for future use by ITU-T | ISO/IEC. Decoders shall ignore ail color remapping information SEI messages containing a value of source_colour_volume_id in the range of 256 to 511, inclusive, or in the range of 2³¹ to 2³² - 2, inclusive, and bitstreams shall not contain such values.

sourcecolourvolumecancelflag equal to 1 indicates that the source color volume SEI message cancels the persistence of any previous source color volume SEI message in output order that applies to the current layer. source_colour_volume_cancel_flag equal to 0 indicates that source color volume follows.

source_colour_volume_persistence_flag spécifiés the persistence of the source color volume SEI message for the current layer. source_colour_volume_persistence_flag equal to 0 spécifiés that the source color volume information applies to the current picture only.

Let picA be the current picture. source_colour_volume_persistence_flag equal to 1 spécifiés that the source color volume persists for the current layer in output order until either of the following conditions is true:

- A new coded-layer video sequence (CLVS) of the current layer begins - The bitstream ends

-719660

- A picture picB in the current layer in an access unit containing a source color volume SEI message with the same value of source_colour_volume_id and applicable to the current layer is output for which PicOrderCnt( picB ) is greater than PicOrderCnt( picA ), where PicOrderCnt( picB ) and PicOrderCnt( picA ) are the PicOrderCntVal values of picB and picA, respectively, immediately after the invocation of the decoding process for picture order count for picB.

source_colour_primaries has the same semantics as specified in clause E.3.1 for the colour_primaries syntax element, except colour_primaries in clause E.3.1 signais the container source color primaries and source_colourjprimaries signais the color primaries the source content truly occupies.

When the value of source_colourjprimaries is equal to 2, the source_colour_primaries is explicitly specified by syntax sourcejprimaries_x[c] and source_primaries_y[c]. source_primaries_x[ c ] and source_primaries_y[ c ] specify the normalized x and y chromaticity coordinates, respectively, of the color primary component c of the source content in incréments of 0.00002, according to the CIE 1931 définition ofx and y as specified in ISO 11664-1 (see also ISO 11664-3 and CIE 15). For describing the source content that use red, green, and blue color primaries, it is suggested that index value c equal to 0 should correspond to the green primary, c equal to 1 should correspond to the blue primary, and c equal to 2 should correspond to the red color primary (see also Annex E and Table E.3). The values of source_primaries_x[ c ] and source_primaries_y[ c ] shall be in the range of 0 to 50,000, inclusive.

max source luminance, min source luminance and avg source luminance specify the nominal maximum, minimum and average luminance, respectively, of the source in units of 0.0001 candelas per square métré (nits). min_source_luminance shall be less than avg_source_luminance and avg_source_luminance shall be less than max_source_luminance. Iuminance_colour_primaries_info_present_flag equal to 1 spécifiés that syntax éléments luminancejprimaries_x and luminancejprimaries_y are présent, luminance_colour_primaries_info_present_flag equal to 0 spécifiés that syntax éléments luminance_primaries_x and luminancejprimaries_y are not présent.

luminance_primaries_x[ i ][ c ] and luminance_primaries_y[ i ][ c ] specify the normalized x and y chromaticity coordinates, respectively, of the color primary component c of the source content at one nominal luminance in incréments of 0.00002, according to the CIE 1931 définition of x and y as specified in ISO 11664-1 (see also ISO 11664-3 and CIE

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15). For describing the source content luminance, the index value 0, 1 and 2 shall correspond to max_source_luminance, min_source_luminance and avg_source_luminance, respectively. For describing the source content that use red, green, and blue color primaries, it is suggested that index value c equal to 0 should correspond to the green primary, c equal to 1 should correspond to the blue primary, and c equal to 2 should correspond to the red color primary (see also Annex E and Table E.3). The values of sourccprimariesxf c ] and sourcejprimaries_y[ c ] shall be in the range of 0 to 50,000, inclusive.

Table 1 provides what is believed to be the minimal information for a useful représentation of source color volume. In an another embodiment, one may décidé to define additional details, 10 like multiple primary expressions [3] or the description of the color primaries of more than three slices of luminance (T), with associated polygons for each slice.

Table 1: Example of source color volume SEI messaging syntax______________________________________

source_colour_volume( payloadSize ) {	Descriptor
sourcecolourvolumeid	ue(v)
sourcecolourvolumecancelflag	u(l)
if( !source_colour_volume cancclflag ) {
source_colour_volume_persistence_flag	u(l)
source_colourjprimaries	u(8)
if( source_colour_primaries == 2 ) {
for( c = 0; c < 3; c++ ) {
source_primaries_x[ c ]	u(16)
source_primaries_y[ c ]	u(16)
Ί J
}
max_source_luminance	u(32)
min_source_luminance	u(32)
avgsource luminance	u(32)
luminance_colour_primaries_info_present_flag	u(D
if( luminance_colour_primaries_info_present_flag ) {
for( i = 0; i <= 3; i++ ) {
for( c = 0; c < 3; c++ ) {
luminance_primaries_x[ i ][ c ]	u(16)
luminance_primaries_y[ i ][ c ]	u(16)
l f
> /
1 J
1 f
}

FIG. 4 depicts an example process for extracting color volume information for a video source using SEI messaging according to an embodiment. First (405), a décoder may detect whether

-919660 a first SEI messaging variable indicating an identifying number (ID) of source color volume information (e.g., source_colour_volume_id) is présent. Then, given the presence of such a variable, the décoder may check (step 407) whether its value is within a permissible range. If it is an illégal value, then the process terminâtes (step 409). If it is a legal value, then in step (410), as shown also in Table 1, the décoder can read additional flags related to the persistence of the first variable across the bit stream (e.g., see the syntax éléments for source_colour_volume_cancel_flag and source_colour_volume_persistence_flag). In step (412), via a second SEI messaging parameter (e.g., source_colour_primaries), a décoder may check whether the metadata define explicitly the color volume that source data content truly occupies. If it is true (e.g., source_colour_primaries = 2) then, in step (420), the (x, y) color chromaticity coordinates for each color primary (e.g., red, green, and blue) are read, otherwise, in step (425), the décoder extracts the minimum, maximum, and average luminance values. Optionally, SEI messaging may also define the (x, y) color chromaticity coordinates corresponding to the color primaries of the min, mid, and max luminance values defined earlier. In an embodiment, this may be indicated by a third parameter (e.g., luminance_colourjprimaries_info_present_flag = 1). If no such information is présent (step 430), then the process terminâtes (409), otherwise, (in step 435), the décoder extracts the (x, y) color chromaticity coordinates for the color primaries for each of the min, mid, and max luminance values.

After extracting the source color volume information, a décoder may use the source color volume data during its display management process (e.g., 140). In an example, display management may include two steps: tone mapping and gamut mapping. The min, mid, and max luminance value can be used to generate a tone mapping curve as described in [6-7], The maximal RGB color gamut and the sliced RGB gamut can be used to perform gamut mapping.

Active Région Considérations

In some embodiments it may be bénéficiai to define an active région as part of the metadata related to the source color volume. For example, when video is encoded in a letterbox format, encoders and decoders should not include the black letterbox areas when computing luma and chroma characteristics of each video frame (e.g., min, max, and average luminance).

Experimental results hâve shown that taking into considération the “framing” or “matting” (e.g., pillarboxing, windowboxing, and letterboxing) of frames in a video sequence can

- 1019660 improve significantly overall output picture quality. Though letter box détection can be implemented by a décoder, thus reducing the signaling overhead to define the active picture région, in an embodiment, such signaling may be explicitly signaled to support decoders with low computational complexity. Table 2 depicts an example of source-color volume SEI messaging with active région signaling according to an embodiment.

Table 2: Example of source color volume SEI message syntax with active région signaling ____________

source_colour_volume( payloadSize ) {	Descriptor
source_colour_volume_id	ue(v)
source_colour_volume_cancel_flag	u(D
if( !source_colour_volume_cancel_flag ) {
source_colour_volume_persistence_flag	u(l)
source_colour_primaries	u(8)
if( source_colour_primaries == 2) {
for( c = 0; c < 3; c++ ) {
source_primaries_x[ c ]	u(16)
source_primaries_y[ c ]	u(16)
f
1 f
max_source_luminance	u(32)
minsourceluminance	u(32)
avg_source_luminance	u(32)
luminance_colour_primaries_info_present_flag	u(l)
if(luminance_colour_primaries_info_present_flag) {
for( i = 0; i <= 3; i++ ) {
for( c = 0; c < 3; c++ ) {
luminance_primaries_x[ i ][ c ]	u(16)
luminance_primaries_y[ i ][ c ]	u(16)
}
l f
1 ___________f______________________ activeregionflag	u(l)
if (active_region_flag) {
activeregionleftoffset	ue(v)
active_region_right_offset	ue(v)
active_region_top_offset	ue(v)
activeregionbottomoffset	ue(v)
f
}
f

Table 2 is a superset of Table 1 and considers two different semantics of defining an active région.

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Semantic 1. In an embodiment, the active région is specified relative to the decoded picture, before conformance window cropping and output. Then the active région parameters may be interpreted as follows:

active_region_flag equal to 1 indicates that the active région offset parameters follow next in the source colour volume information SEI message. active_region_flag equal to 0 indicates that the active région offset parameters are not présent.

activeregionleftoffset, activeregionrightoffset, activeregiontopoffset, and active_region_bottom_offset specify an active rectangular région. When active_region_flag is equal to 0, the values of active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset are inferred to be equal to 0. The active région is defined with horizontal picture coordinates from SubWidthC * active_region_left_offset to pic_width_in_luma_samples - ( SubWidthC * active_region_right_offset + 1 ) and vertical picture coordinates from SubHeightC * active_region_top_offset to pic_height_in_luma_samples - ( SubHeightC * active_region_bottom_offset + 1 ), inclusive. The value of SubWidthC * ( active_region_left_offset + active_region_right_offset ) shall be less than pic_width_in_luma_samples, and the value of

SubHeightC * ( active_region_top_offset + active_region_bottom_offset ) shall be less than pic_height_in_luma_samples.

Semantic 2. In an embodiment, the active région offset values are defined relative to the final output picture to display, therefore the conformance window parameters need to be taken into considération. Then the active région parameters may be interpreted as follows: active_region_flag equal to 1 indicates that the active région offset parameters follow next in the source colour volume information SEI message. active_region_flag equal to 0 indicates that the active région offset parameters are not présent.

active region left offset, active region right offset, active region top offset, and active_region_bottom_offset specify an active rectangular région. When active_region_flag is equal to 0, the values of active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset are inferred to be equal to 0.

The active région is defined with horizontal picture coordinates from active_region_left_offset + SubWidthC * conf_win_left_offset to CtbSizeY * PicWidthlnCtbsY - SubWidthC * conf_win_right_offset - active_region_right

- 1219660 _offset - 1 and vertical picture coordinates from active_region_top_offset + SubHeightC * conf_win_top_offset to

CtbSizeY * PicHeightlnCtbsY - SubHeightC * conf_win_bottom_offset active_region_bottom_offset - 1 , inclusive.

The value of ( active_region_left_offset + active_region_right_offset ) shall be less than CtbSizeY * PicWidthlnCtbsY - SubWidthC * (conf_win_right_offset + conf_win_left_offset), and the value of ( active_region_top_offset + active_region_bottom_offset ) shall be less than CtbSizeY * PicHeightlnCtbsY - SubHeightC * (conf_win_bottom_offset + conf_win_top_offset ).

Each of the references listed below is incorporated herein by reference in its entirety.

Référencés

[1] Rec. ITU-T H.265, “Sériés H: Audiovisual and Multimedia Systems, Infrastructure of audiovisual services - Coding of moving video, High efficiency video coding,” ITU, Oct. 2014.

[2] H.M. Oh et al., Content colour gamut SEI message, JCTVC-X0040, May 2016, Geneva, CH.

[3] A.M. Tourapis, Improvements to the Effective Colour Volume SEI, JCTVC-X0052, May 2016, Geneva, CH.

[4] A.K. Ramasubramonian, Content colour volume SEI message , JCTVC-X0052, May 2016, Geneva, CH.

[5] SMPTE ST 2094-1:2016: Dynamic Metadata for Color Volume Transform - Core Components, SMPTE, May 18, 2016.

[6] SMPTE ST 2094-10:2016: Dynamic Metadata for Color Volume Transform Application #1, SMPTE, May 18, 2016.

[7] R. Atkins et al., U.S. Patent Publication US2016/0005349, “Display management for high dynamic range video.”

Example Computer System Implémentation

Embodiments of the présent invention may be implemented with a computer System, Systems configured in electronic circuitry and components, an integrated circuit (IC) device such as a microcontroller, a field programmable gâte array (FPGA), or another configurable or programmable logic device (PLD), a discrète time or digital signal processor (DSP), an application spécifie IC (AS IC), and/or apparatus that includes one or more of such Systems, devices or components. The computer and/or IC may perform, control, or execute

- 13 19660 instructions related to communicating source color volume information using SEI messaging, such as those described herein. The computer and/or IC may compute any of a variety of parameters or values that relate to the processes described herein. The image and video embodiments may be implemented in hardware, software, firmware and various combinations thereof.

Certain implémentations of the invention comprise computer processors which execute software instructions which cause the processors to perform a method of the invention. For example, one or more processors in a display, an encoder, a set top box, a transcoder or the like may implement methods related to communicating source color volume information using SEI messaging as described above by executing software instructions in a program memory accessible to the processors. The invention may also be provided in the form of a program product. The program product may comprise any non-transitory medium which carries a set of computer-readable signais comprising instructions which, when executed by a data processor, cause the data processor to execute a method of the invention. Program products according to the invention may be in any of a wide variety of forms. The program product may comprise, for example, physical media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, or the like. The computer-readable signais on the program product may optionally be compressed or encrypted.

Where a component (e.g. a software module, processor, assembly, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a means) should be interpreted as including as équivalents of that component any component which perforais the function of the described component (e.g., that is functionally équivalent), including components which are not stracturally équivalent to the disclosed structure which perforais the function in the illustrated example embodiments of the invention.

Equivalents, Extensions, Alternatives and Miscellaneous

Example embodiments that relate to communicating source color volume information using SEI messaging are thus described. In the foregoing spécification, embodiments of the présent invention hâve been described with reference to numerous spécifie details that may vary from implémentation to implémentation. Thus, the sole and exclusive indicator of what is the invention, and is intended by the applicants to be the invention, is the set of claims that issue

- 1419660 from this application, in the spécifie form in which such claims issue, including any subséquent correction. Any définitions expressly set forth herein for tenus contained in such claims shall govem the meaning of such tenus as used in the claims. Hence, no limitation, element, property, feature, advantage or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. The spécification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Claims (15)

1. What is claimed is:

   1. A method in a décoder to extract source color volume information of an input bitstream from an SEI message, the method executed on a processor, the method comprising:

   receiving, by the processor, the SEI message that includes a source color volume identification SEI messaging variable identifying the presence of source color volume information in the SEI message;

   receiving, by the processor, a first SEI messaging variable as part of the source color volume information in the SEI message;

   if the first SEI messaging variable matches a first predetermined value, then for each of one or more color primaries, extracting, by the processor, first x and y chromaticity coordinates from the source color volume information in the SEI message, the first x and y chromaticity coordinates of the one or more color primaries defining a maximum 2D color gamut of the source color volume;

   extracting, by the processor, a minimum, a maximum, and an average luminance value from the source color volume information in the SEI message, wherein the minimum, the maximum, and the average luminance values are for an active région of one or more decoded pictures in the input bitstream; and generating an output video signal based on the input bitstream and the extracted source color volume information.
2. 2. The method of claim 1, further comprising:

   receiving, by the processor, a second SEI messaging variable as part of the source color volume information in the SEI message; and if the second SEI messaging variable matches a second predetermined value, then for each of one or more color primaries, extracting, by the processor, second x and y chromaticity coordinates for each of the minimum, maximum, and average luminance values from the source color volume information in the SEI message, the second x and y chromaticity coordinates of the one or more color primaries identifying a sliced 2D color gamut of the source color volume at the minimum, maximum and average luminance values, respectively.

   - 1619660
3. 3. The method of claim 1, further comprising extracting, by the processor, a third SEI messaging variable from the source color volume information in the SEI message, wherein if the third SEI messaging variable is equal to 0, it indicates that source color volume information follows in the source color volume information, and if it is 1, it indicates canceling any previous message related to persistence of source color volume information in the input bitstream.
4. 4. The method of claim 1, further comprising extracting, by the processor, a fourth SEI messaging variable from the source color volume information in the SEI message, wherein the fourth SEI messaging variable is related to persistence of the source color volume information in the input bitstream.
5. 5. The method of claim 1, wherein the first predetermined value is equal to 2.
6. 6. The method of claim 2, wherein the second predetermined value is equal to 1.
7. 7. The method of claim 1, further comprising receiving a fifth SEI messaging variable as part of the source color volume information in the SEI message, wherein the fifth SEI messaging variable indicates the presence of information related to the active région in the one or more decoded pictures in the input bitstream .
8. 8. The method of claim 7, wherein the information related to the active région comprises at least one of a left offset, a right offset, a top offset, and a bottom offset for the active région.
9. 9. An apparatus comprising a video bitstream stored on one or more non-transitory machinereadable media, the bitstream characterized by:

   data representing one or more picture frames in a compressed format, wherein a portion of the data that represents the one or more picture frames in the compressed format comprises:

   a SEI message including a source color volume identification SEI messaging variable identifying the presence of source color volume information in the SEI message, wherein the source color volume information in the SEI message further comprises:

   - 1719660 a first SEI messaging variable indicating the presence of a first set of x and y chromaticity coordinates for one or more color primaries for identifying a maximum 2D color gamut of the source color volume of the data in the bitstream; and a minimum, a maximum, and an average luminance variable for the data in the bitstream, wherein the minimum, the maximum, and the average luminance variables are for an active région of one or more decoded pictures in the bitstream. .
10. 10. The apparatus of claim 9, wherein the SEI message further comprises:

    a second SEI messaging variable indicating the presence of a second set of x and y chromaticity coordinates for one or more color primaries of the minimum, maximum, and average luminance variables for identifying 2D sliced color gamut of the source color volume of the data in the bitstream at the minimum, maximum and average luminance values, respectively.
11. 11. The apparatus of claim 9, the source color volume information in the SEI message further comprising a third SEI messaging variable indicating the presence of information related to the active région.
12. 12. The apparatus of claim 11, wherein the information related to the active région comprises at least one of a left offset, a right offset, a top offset, and a bottom offset for the active région.
13. 13. The apparatus of claim 9, wherein the average luminance variable applies to more than one picture in the bitstream.
14. 14. An apparatus comprising a processor and configured to perform any one of the methods recited in claims 1-8.
15. 15. A non-transitory computer-readable storage medium having stored thereon computerexecutable instruction for executing a method with one or more processors in accordance with any of the claims 1-8.