Computer readable storage medium related to processing of source color volume information

Abstract

Computer readable storage media related to processing of source color volume information are described. Such data includes at least minimum, maximum, and average luminance values ​​in the source data plus optional data, which may include: color volume x and y chromaticity coordinates of input primary colors (e.g., red, green, and blue) of the source data, and color x and y chromaticity coordinates of the primary colors corresponding to the minimum, average, and maximum luminance values ​​in the source data. Messaging data signaling valid areas in each picture may also be included.

Description

[0001] Division Statement

[0002] This application is a divisional application of the invention patent application with PCT international application number PCT / US2017 / 054920, international application date October 3, 2017, application number 201780069607.7 entering the Chinese national phase and invention name “Source Color Volume Information Message Transmission”.

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 427,677, filed on November 29, 2016, and U.S. Provisional Patent Application No. 62 / 404,302, filed on October 5, 2016, both of which are incorporated herein by reference in their entirety. Technical Field

[0005] The present invention relates generally to images. More specifically, embodiments of the present invention relate to communicating and processing source color volume information. Background Art

[0006] Recommendation ITU-T H.265 [1] (also known as HEVC) for “Mobile Video Coding” in Annex D, “Supplemental Enhancement Information” (SEI), and “Video Usability Information” (VUI) in Annex E describes the syntax for providing supplementary SEI and VUI information in the coded bitstream to enable the decoder to better map the decoded samples to the display.

[0007] In parallel with the MPEG / ITU standardization process, the Society of Motion Picture and Television Engineers (SMPTE) has also defined a number of recommendations related to metadata related to conveying color volume information for both source video and targeted displays. For example, the SMPTE ST 2094 document suite (e.g., [5] and [6]) defines metadata for use in color volume transformations of video content. These metadata can vary on a scene-by-scene or frame-by-frame basis. For example, such metadata can assist a decoder in rendering high dynamic range (HDR) and wide color gamut (WCG) data on a display having a smaller color volume than the master display used for the master source image.

[0008] As used herein, the term "metadata" refers to any auxiliary information that is transmitted as part of the encoded bitstream and assists a decoder in rendering a decoded image. Such metadata may include, but is not limited to, color space or gamut information, prediction parameters, reference display parameters, and auxiliary signal parameters, such as those described herein.

[0009] While Annexes D and E of H.265 support a lot of color volume related metadata, they do not carry all the metadata needed for the most efficient display management of HDR content. In July 2016, at the Joint Collaborative Team on Video Coding (JCT-VC) meeting in Geneva, three proposals were presented on how to use SEI or VUI messaging to describe content color volume information [2-4]. Some of these proposals were influenced by SMPTE ST.2094 [5], but their scopes are quite different.

[0010] In [2], for the signal content color gamut in 2D, a content-SEI message is proposed, which describes the actual color distribution of the video content. In the VUI, the variable colour_primaries is used to indicate the container color gamut instead of the true source color gamut [1]. In [3], it is proposed to associate multiple primary color expressions and spatial regions with identified source characteristics. In [4], a content color volume SEI message is proposed to indicate the color volume occupied by the content. It uses (x, y, Y) description for color coordinates and has multiple slices of luminance Y, each of which has an associated polygon. These proposals have many disadvantages, such as: providing rarely used information to most display manufacturers may add a lot of overhead and may require too much computational overhead. As the inventors understand herein, in order to improve existing encoding and decoding schemes, improved techniques for generating and communicating source color volume information are needed.

[0011] The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any approach described in this section qualifies as prior art simply by virtue of its inclusion in this section. Similarly, unless otherwise indicated, problems identified with respect to one or more approaches should not be considered to have been recognized as prior art based on this section. Summary of the invention

[0012] According to some embodiments of the present disclosure, a computer-readable storage medium is provided, the computer-readable storage medium having computer-executable instructions stored thereon, the computer-executable instructions, when executed by a processor, causing the processor to perform operations, the operations comprising: receiving a first SEI message transmission variable as part of source color volume information in a supplemental enhancement information SEI message; if the first SEI message transmission variable matches a first predetermined value, extracting first x and y chromaticity coordinates from the source color volume information in the SEI message for each of one or more primary colors, the first x and y chromaticity coordinates of the one or more primary colors defining a maximum 2D color gamut of the source color volume; extracting a minimum brightness value, a maximum brightness value, and an average brightness value from the source color volume information in the SEI message, wherein the minimum brightness value, the maximum brightness value, and the average brightness value are used for valid areas of one or more decoded pictures in an input bitstream; and generating an output video signal based on the input bitstream and the extracted source color volume information.

[0013] According to some embodiments of the present disclosure, a computer-readable storage medium is provided, the computer-readable storage medium having computer-executable instructions stored thereon, the computer-executable instructions, when executed by a processor, causing the processor to perform operations, the operations comprising: obtaining data representing one or more picture frames in a compressed format, wherein the data representing the one or more picture frames in the compressed format comprises: a supplemental enhancement information (SEI) message, wherein source color volume information in the SEI message comprises: a first SEI message transmission variable, wherein the first SEI message transmission variable indicates that there is a first set of x and y chromaticity coordinates of one or more primary colors of a maximum 2D color gamut for identifying a source color volume of the data in a bitstream; and a minimum brightness value, a maximum brightness value, and an average brightness value of the data in the bitstream, wherein the minimum brightness value, the maximum brightness value, and the average brightness value are used for valid areas of one or more decoded pictures in the bitstream; and encoding the data representing the one or more picture frames in the compressed format to generate an encoded video bitstream. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments of the invention are illustrated by way of example and not limitation in the accompanying drawings and in which like reference numerals refer to like elements and in which:

[0015] Figure 1 depicts an example process of a video delivery pipeline according to an embodiment of the present invention;

[0016] Figure 2 An example of a "largest" possible color volume map for a video container format is depicted;

[0017] Figure 3A Depicts an example of the source content color gamut within the container color volume;

[0018] Figure 3B and Figure 3C depicts examples of 2D slices of container and source color volumes at specific luminance (Y) values; and

[0019] Figure 4 An example process for extracting source color volume information from SEI messaging according to an embodiment of the present invention is depicted. DETAILED DESCRIPTION

[0020] This article describes a technique for conveying source color volume information using SEI messaging. In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent that the present invention can be implemented without these specific details. In other cases, in order to avoid unnecessary obscuration, obscurity or confusion of the present invention, well-known structures and devices are not described in detail.

[0021] Overview

[0022] Example embodiments described herein relate to techniques for communicating source color volume information using SEI messaging. In a decoder, a processor for extracting SEI messaging receives a source color volume identification messaging variable that identifies 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 primary colors, the processor generates an x ​​chromaticity coordinate and a y chromaticity coordinate for the one or more primary colors based on the source color volume information in the input bitstream. The processor generates a minimum luminance value, a maximum luminance value, 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 primary colors, the processor generates an x ​​chromaticity coordinate and a y chromaticity coordinate for the one or more primary colors corresponding to the minimum luminance value, the maximum luminance value, and the average luminance value based on the source color volume information.

[0023] Example of Source Color Volume Messaging

[0024] Figure 1An example process of a video delivery pipeline (100) is depicted, showing various stages from video capture to display of video content. An image generation block (105) is used to capture or generate a sequence of video frames (102). The video frames (102) may be digitally captured (e.g., by a digital camera) or generated by a computer (e.g., using computer animation) to provide video data (107). Alternatively, the video frames (102) may be captured on film by a film camera. The film is converted to a digital format after appropriate editing (not shown) to provide video data (107).

[0025] 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 the color or brightness in specific areas of the image to enhance the image quality or achieve a specific look of the image in accordance with the creative intent of the video creator. This is sometimes referred to as "color timing" or "color grading." Other edits (e.g., scene selection and sequencing, image cropping, adding computer-generated visual effects, etc.) may be performed at block (110) to produce a final version (112) of the work for distribution. During post-production editing (110), the video image is viewed on a reference display (125) (also referred to as a "targeted display" because the production studio has optimized the video for it).

[0026] In some embodiments, before video encoding (120), the video content may be analyzed to extract source color volume metadata (119), such as defined in SMPTE ST 2094-1 [5], or as defined later in this disclosure. Such metadata may also define characteristics of a targeted display (e.g., a reference display (125)) and color remapping information so that a downstream receiver can present the decoded data in the best possible manner.

[0027] After post-production (110) and source color volume analysis (115), the video data and associated metadata (119) of the final work (117) can be delivered to the encoding block (120) in an appropriate color format (e.g., 10-bit YCbCr, ICtCp, etc. in 4:2:0) for downstream delivery to decoding and playback devices such as televisions, set-top boxes, movie theaters, etc. In some embodiments, the encoding block (120) can include an audio encoder and a video encoder such as those defined by ATSC, DVB, DVD, Blu-ray, and other delivery formats to generate an encoded bitstream (122). The encoded bitstream (122) can be represented by a single-layer video encoded bitstream or by a multi-layer bitstream. For example, in a multi-layer bitstream, the signal (122) can include a base layer (e.g., an SDR layer or a 10-bit HDR (HDR10) layer) and an enhancement layer that, when combined with the base layer, produces an HDR bitstream (e.g., a 12-bit HDR signal) having a higher dynamic range than the base layer alone. The signal (122) (ie, the output bitstream from the encoder (120)) may also include metadata (119) and additional encoding-related metadata, such as prediction parameters and other data, to assist a decoder in better reconstructing the HDR signal.

[0028] In a receiver, the encoded bitstream (122) is decoded by a decoding unit (130) to generate a decoded signal (132) and associated metadata (119). The receiver (or target) display (150) may have completely different characteristics than the reference (or targeted) display (125). For example, but not limited to, the reference display (125) may be a 1,000 nit display, while the receiver display may be a 500 nit display. In this case, a display management module (140) may be used to map the dynamic range of the decoded signal (132) to the characteristics of the receiver display (150) by generating a display mapping signal (142). As used herein, the term "display management" refers to 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). The display management unit (140) may take the metadata (119) into account to improve the quality of the output video on the display (150). For example, as shown in [7], information about the brightness range of the targeted (or reference) display (e.g., 125) and the source data can be used at the receiver to better map the dynamic range of the video content to the receiver display (e.g., 150).

[0029] Color Volume Information

[0030] Figure 2An example of a "maximum" possible color volume (also referred to as a "container color volume") for a predefined container format (e.g., BT.2020) is depicted. Such a volume can be composed of two-dimensional (2D) color gamut primaries, white point chromaticity (e.g., D65), maximum luminance value (e.g., L 最大 =4,000 nits), and a minimum luminance value (e.g., 0.005 nits). This graph indicates the maximum possible color volume boundaries for all colors in the source video content.

[0031] In practice, if Figure 3A The darker "cloud" (305) or Figure 3B and Figure 3C As depicted by the darker area (305) in the image, the source color volume for source content (e.g., 112) within a particular frame or even an entire scene can be significantly smaller than the maximum possible color volume (310). Because actual color volumes (305) have very irregular shapes, transmitting such source color volume information for each frame or entire scene requires a large amount of information. For example, in an embodiment, color gamut information can be signaled for multiple luma values ​​(e.g., 0.1, 1, 10, etc.). The question then becomes: how many luma values ​​are there and which are the most important ones? It is also necessary to consider not only the overhead required to encode such information on the bitstream, but also the complexity of generating such content on the encoder and / or reconstructing the color volume information on the decoder.

[0032] While it is important to communicate the minimum and maximum luminance values ​​in the source content, as the inventors appreciate, it is also valuable for the receiver to communicate the average luminance (or midpoint luminance). Together, these three values ​​can help generate a reasonable tone curve for display mapping. In the present disclosure, it is proposed to signal the following metadata to describe the source color volume: a) the maximum 2D color space occupied by the source (e.g., the source color volume); b) the maximum luminance, minimum luminance, and average luminance of the source; and c) optionally, the cut-up (2D) color space for these three luminance values ​​(e.g., see Figure 3B and Figure 3C ). It is assumed that the white point of the container primaries and the source content primaries should be the same, so there is no reason to retransmit such information. This information can be updated as needed, for example on a frame-by-frame or scene-by-scene basis. Figure 3B and Figure 3C Depicted are examples of 2D slices of a source color volume (305) and a container color volume (310) at specific luminance (Y) values. Figure 3B In the 2D slice, Y = 84 nits, and Figure 3CIn , the 2D slice is Y=246 nits. For illustration purposes only, a chrominance (rgb) triangle around the source color volume (305) and within the container RGB space is provided. The encoder may choose to define smaller or larger such regions and communicate them to the receiver.

[0033] Table 1 depicts an example of source color volume SEI messaging that follows the naming and syntax of the H.265 specification according to an embodiment. The description of the primary colors follows the definition of the CIE 1931 (x, y) color chromaticity coordinates for the primary colors as defined in ISO 11664-1 (see also ISO 11664-3 and CIE 15), and uses red, green, and blue primaries. Other types of primary colors may also be used, such as four, five, or six, or other polygon-based primary color representations. For the maximum practical color gamut in the source content, in an embodiment, but not limited to, the syntax is similar to the definition of the colour_primaries parameter (or variable) defined in Section E.3.1 (Table E.3) of the H.265 specification. 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" defined in SMPTE EG 432-1 and SMPTE RP 431-2). Therefore, in those cases where the source gamut is less than or equal to P3, or equal to BT.2020 / 2010 primaries, Table E.3 may be used; however, for sources whose gamut is greater than P3 but less than BT.2020 / 2010, it may be necessary to explicitly signal the gamut. Luminance values ​​are expressed in nits (cd / m 2 ) is specified by the absolute value of the luma value in units of . Alternatively, to save bits, the luma values ​​may also be encoded using a non-linear representation, for example as values ​​encoded according to the inverse EOTF of SMPTE ST 2084. The color gamut information corresponding to the maximum luma value, the minimum luma value, and the average (median) luma value is made optional to allow applications to reduce metadata overhead as needed.

[0034] NOTE: 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 the 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 12b to 10b), since chroma subsampling or bit depth conversion will modify the color volume information. 2) The source color domain is typically different from the container primaries, which are indicated in Annex E of H.265 (e.g., Table E.3). 3) The source color volume is typically different from the master display color volume, which may be indicated by a master display color volume SEI message.

[0035] In an example embodiment, the parameters (or variables) and encoding semantics in Table 1 may be described as follows:

[0036] source_colour_volume_id contains an identification number that can be used for the purpose of identifying the source colour volume. The value of source_colour_volume_id should be between 0 and 2. 32 -2, inclusive. As determined by the application, values ​​from 0 to 255 and from 512 to 2 may be used. 31 -1. Reserved values ​​from 256 to 511 (inclusive) and from 2 31 To 2 32 Source_colour_volume_id values ​​in the range 256 to 511 (inclusive) or in the range 2 are for future use by ITU-T | ISO / IEC. Decoders shall ignore values ​​in the range 256 to 511 (inclusive) or in the range 2 31 To 2 32 The bitstream shall not contain any color remap information SEI messages containing values ​​of source_colour_volume_id in the range -1 to -2 (inclusive), and the bitstream shall not contain such values.

[0037] source_colour_volume_cancel_flag equal to 1 indicates that the source colour volume SEI message cancels the persistence of any previous source colour volume SEI message applied to the current layer in output order. source_colour_volume_cancel_flag equal to 0 indicates that the source colour volume follows.

[0038] source_colour_volume_persistence_flag specifies the persistence of the source colour volume SEI message for the current layer. source_colour_volume_persistence_flag equal to 0 specifies that the source colour volume information applies only to the current picture.

[0039] Make picA the current picture. source_colour_volume_persistence_flag equal to 1 specifies that the source colour volume persists in the current layer in output order until any of the following conditions is true:

[0040] - A new coded layer video sequence (CLVS) for the current layer starts

[0041] - End of bitstream

[0042] - a picture picB in the current layer in the output access unit, the picture picB containing a source colour volume SEI message applicable to the current layer with the same value of source_colour_volume_id, for which picture picB, PicOrderCnt(picB) is greater than PicOrderCnt(picA), where PicOrderCnt(picB) and PicOrderCnt(picA) are the respective PicOrderCntVal values ​​of picB and picA immediately after the decoding process was invoked for the picture order count of picB.

[0043] source_colour_primaries has the same semantics as specified in clause E.3.1 of the colour_primaries syntax element, the difference being that the colour_primaries in clause E.3.1 signals the container source primaries, whereas source_colour_primaries signals the primaries that the source content actually occupies.

[0044] When the value of source_colour_primaries is equal to 2, source_colour_primaries is explicitly specified by the syntax source_primaries_x[c] and source_primaries_y[c].

[0045] source_primaries_x[c] and source_primaries_y[c] specify the normalized x and y chromaticity coordinates, respectively, of the primary color component c of the source content, according to the CIE 1931 definitions of x and y as specified in ISO 11664-1 (see also ISO 11664-3 and CIE 15), in increments of 0.00002. To describe source content using red, green, and blue primaries, it is recommended that an 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 primary (see also Annex E and Table E.3). The values ​​of source_primaries_x[c] and source_primaries_y[c] SHOULD be in the range 0 to 50,000, inclusive.

[0046] max_source_luminance, min_source_luminance, and avg_source_luminance specify the nominal maximum, minimum, and average luminance of the source, respectively, in units of 0.0001 cd / m2 (nits). min_source_luminance should be less than avg_source_luminance, and avg_source_luminance should be less than max_source_luminance.

[0047] luminance_colour_primaries_info_present_flag (luminance_colour_primaries_info_present_flag) equal to 1 specifies that the syntax elements luminance_primaries_x and luminance_primaries_y are present, and luminance_colour_primaries_info_present_flag equal to 0 specifies that the syntax elements luminance_primaries_x and luminance_primaries_y are not present.

[0048] luminance_primaries_x[i][c] and luminance_primaries_y[i][c] specify the normalized x and y chromaticity coordinates, respectively, of the source content primary component c at a nominal luminance, in increments of 0.00002, according to the CIE 1931 definitions of x and y as specified in ISO 11664-1 (see also ISO 11664-3 and CIE 15). For describing source content luminance, index values ​​0, 1, and 2 shall correspond to max_source_luminance, min_source_luminance, and avg_source_luminance, respectively. For describing source content using red, green, and blue primaries, it is recommended that index values ​​c equal to 0 shall correspond to the green primary, c equal to 1 shall correspond to the blue primary, and c equal to 2 shall correspond to the red primary (see also Annex E and Table E.3). The values ​​of source_primaries_x[c] and source_primaries_y[c] should be in the range of 0 to 50,000 (inclusive).

[0049] Table 1 provides the minimum information to be considered a useful representation of the source color volume. In another embodiment, one may decide to define additional details, such as multiple primary color expressions [3], or descriptions of primaries for more than three luminance (Y) slices, each with an associated polygon.

[0050] Table 1: Example of source color volume SEI messaging syntax

[0051]

[0052]

[0053] Figure 4 An example process for extracting color volume information of a video source using SEI messaging according to an embodiment is depicted. First (405), the decoder can detect whether there is a first SEI messaging variable indicating an identification number (ID) (e.g., source_colour_volume_id) of the source color volume information. Then, considering the presence of such a variable, the decoder can check (step 407) whether the value of the variable is within an allowable range. If it is an illegal value, the process terminates (step 409). If it is a legal value, then in step (410), as also shown in Table 1, the decoder can read additional flags related to the persistence of the first variable on the bitstream (e.g., see the syntax elements of 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), the decoder can check whether the metadata clearly defines the color volume actually occupied by the source data content. If true (e.g., source_colour_primaries=2), then in step (420), the (x, y) color chromaticity coordinates of each primary color (e.g., red, green, and blue) are read, otherwise, in step (425), the decoder extracts the minimum luminance value, the maximum luminance value, and the average luminance value. Optionally, the SEI message transmission may also define the (x, y) color chromaticity coordinates corresponding to the primaries having the minimum luminance value, the intermediate luminance value, and the maximum luminance value defined earlier. In an embodiment, this may be indicated by a third parameter (e.g., luminance_colour_primaries_info_present_flag=1). If such information is not present (step 430), the process terminates (409), otherwise, (in step 435), the decoder extracts the (x, y) color chromaticity coordinates of the primary colors for each of the minimum luminance value, the intermediate luminance value, and the maximum luminance value.

[0054] After extracting the source color volume information, the decoder can use the source color volume data during its display management process (e.g., 140). In an example, display management can include two steps: tone mapping and gamut mapping. The minimum luminance value, the middle luminance value, and the maximum luminance value can be used to generate a tone mapping curve as described in [6-7]. The maximum RGB gamut and the slice RGB gamut can be used to perform gamut mapping.

[0055] Considerations for the active region

[0056] In some embodiments, it may be beneficial to define a valid region as part of metadata related to the source color volume. For example, when encoding a video in a letterbox format, the encoder and decoder should not include black letterbox regions when calculating the luminance and chrominance characteristics (e.g., minimum luminance, maximum luminance, and average luminance) of each video frame. Experimental results show that considering "framing" or "matting" of frames in a video sequence (e.g., pillarboxing, windowboxing, and letterboxing) can significantly improve the overall output picture quality. Although the horizontal black border detection can be implemented by the decoder, thereby reducing the signaling overhead for defining the valid picture area, in an embodiment, such signaling can be explicitly signaled to support a decoder with low computational complexity. Table 2 depicts an example of source color volume SEI message transmission with valid region signaling according to an embodiment.

[0057] Table 2: Example of source color volume SEI message syntax with valid region signaling

[0058]

[0059]

[0060] Table 2 is a superset of Table 1 and considers two different semantics for defining the valid region.

[0061] Semantics 1. In an embodiment, the valid region is specified relative to the decoded picture before cropping and outputting the consistency window. The valid region parameters can then be interpreted as follows:

[0062] active_region_flag equal to 1 indicates that the active region offset parameter follows in the source color volume information SEI message. active_region_flag equal to 0 indicates that there are no active region offset parameters.

[0063] active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset specify the valid rectangular region. 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.

[0064] The active region is defined by 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.

[0065] Semantics 2. In an embodiment, the valid region offset value is defined relative to the final output picture to be displayed, so the consistency window parameter needs to be considered. Then, the valid region parameter can be interpreted as follows:

[0066] active_region_flag equal to 1 indicates that active region offset parameters follow next in the source color volume information SEI message. active_region_flag equal to 0 indicates that no active region offset parameters are present.

[0067] active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset specify the valid rectangular region. 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.

[0068] The active region is defined using horizontal image coordinates from active_region_left_offset + SubWidthC*conf_win_left_offset to CtbSizeY*PicWidthInCtbsY - SubWidthC*conf_win_right_offset - active_region_right_offset - 1, and vertical image coordinates from active_region_top_offset + SubHeightC*conf_win_top_offset to CtbSizeY*PicHeightInCtbsY - SubHeightC*conf_win_bottom_offset - active_region_bottom_offset - 1, including the endpoints.

[0069] The value of (active_region_left_offset+active_region_right_offset) should be less than CtbSizeY*PicWidthInCtbsY-SubWidthC*(conf_win_right_offset+conf_win_left_offset), and the value of (active_region_top_offset+active_region_bottom_offset) should be less than CtbSizeY*PicHeightInCtbsY-SubHeightC*(conf_win_bottom_offset+conf_win_top_offset).

[0070] Each of the references listed below is incorporated herein by reference in its entirety.

[0071] References

[0072] [1] Recommendation ITU-T H.265, “Series H: Audiovisual and Multimedia systems, Infrastructure of audiovisual services – Coding of moving video, High efficiency video coding”, ITU, October 2014.

[0073] [2] HM Oh et al., “Content colour gamut SEI message”, JCTVC-X0040, May 2016, Geneva, CH.

[0074] [3] AMTourapis, “Improvements to the Effective Colour Volume SEI”, JCTVC-X0052, May 2016, Geneva, CH.

[0075] [4] A.K. Ramasubramonian, “Content colour volume SEI message”, JCTVC-X0069, May 2016, Geneva, CH.

[0076] [5] SMPTE ST 2094-1:2016: “Dynamic Metadata for Color Volume Transform–Core Components”, SMPTE, May 18, 2016.

[0077] [6] SMPTE ST 2094-10:2016: “Dynamic Metadata for Color Volume Transform–Application #1”, SMPTE, May 18, 2016.

[0078] [7] R. Atkins et al., U.S. Patent Publication No. US2016 / 0005349, “Display Management for High Dynamic Range Video”.

[0079] Example Computer System Implementation

[0080] Embodiments of the present invention may be implemented using computer systems, systems configured with electronic circuits and components, integrated circuit (IC) devices (such as microcontrollers, field programmable gate arrays (FPGAs), or other configurable or programmable logic devices (PLDs), discrete time or digital signal processors (DSPs), application specific ICs (ASICs), and / or devices including one or more such systems, devices, or components. The computer and / or IC may execute, control, or perform instructions related to communicating source color volume information using SEI messaging, such as those described herein. The computer and / or IC may calculate any of the various parameters or values ​​related to the processes described herein. The image and video embodiments may be implemented in hardware, software, firmware, and various combinations thereof.

[0081] Certain embodiments of the present invention include a computer processor that executes software instructions that cause the processor to perform the method of the present invention. For example, one or more processors in a display, an encoder, a set-top box, a transcoder, etc. can implement methods related to the use of SEI messaging as described above to convey source color volume information by executing software instructions in a program memory accessible to the processor. The present invention can also be provided in the form of a program product. The program product may include any non-transitory medium that carries a set of computer-readable signals, the set of computer-readable signals including instructions that, when executed by a data processor, cause the data processor to perform the method of the present invention. The program product according to the present invention may take any of a variety of forms. The program product may include, for example, physical media, such as magnetic data storage media including floppy disks, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAMs, etc. The computer-readable signals on the program product may optionally be compressed or encrypted.

[0082] Where components (e.g., software modules, processors, components, devices, circuits, etc.) are mentioned above, unless otherwise specified, references to such components (including references to "devices") should be interpreted as including equivalents (e.g., functionally equivalent) of any components that perform the functions of the described components as such components, including components that are not structurally equivalent to the disclosed structures that perform the functions in the example embodiments described in the present invention.

[0083] Equivalents, extensions, alternatives and miscellaneous

[0084] Thus described are example embodiments involving the use of SEI messaging to convey source color volume information. In the foregoing specification, embodiments of the invention have been described with reference to many specific details, which may vary depending on the implementation. Therefore, what is the invention, and what the applicant intends as the sole and exclusive indicator of the invention, are the claims issued from this application in the specific form in which the claims issue, including any subsequent amendments. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of such terms used in the claims. Therefore, limitations, elements, properties, features, advantages, or attributes that are not expressly recited in a claim should not limit the scope of such claim in any way. Accordingly, the specification and drawings should be regarded as illustrative rather than in a restrictive sense.

Claims

1. A method in a decoder for extracting source color volume information of an input bitstream from an SEI message, the method comprising: Receiving an SEI message, the SEI message including one or more source color SEI parameters, the one or more source color SEI parameters including primary color component parameters and brightness value parameters; for a primary color component c, extracting x and y chromaticity coordinates from the primary color component parameters, wherein the x and y chromaticity coordinates respectively define normalized x and y chromaticity coordinates of the primary color component c of the input bitstream, the normalized x and y chromaticity coordinates of the primary color component defining a maximum 2D color gamut of the source color volume; and An average luminance value of the source is extracted from the luminance value parameter, wherein the average luminance value is used for a valid area of ​​one or more decoded pictures in the input bitstream that are encoded in a horizontal black-letter format.

2. The method of claim 1, further comprising generating an output video signal based on the input bitstream, the x and y chromaticity coordinates of the primary color component c, and the average luminance value.

3. The method of claim 1, wherein: The x and y chromaticity coordinates are specified in increments of 0.00002 according to the CIE 1931 definition of x and y as specified in ISO 11664-1.

4. The method of claim 1, wherein: To describe the color volume using red, green, and blue primaries, c=0 corresponds to the green primary, c=1 corresponds to the blue primary, and c=2 corresponds to the red primary.

5. An apparatus for image processing, the apparatus comprising a processor and configured to execute the method according to any one of claims 1 to 4.

6. A computer program product, comprising computer executable instructions for executing the method according to any one of claims 1 to 4 by one or more processors.

Images