Apparatus related to processing of source color volume information

Abstract

An apparatus related to the processing of source color volume information is described. Such data includes at least a minimum luminance value, a maximum luminance value, and an average luminance value in the source data, plus optional data that may include: color volume x and y chromaticity coordinates of the 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 luminance value, the average luminance value, and the maximum luminance value in the source data. Messaging data indicating the valid regions in each picture may also be included.

Description

[0001] Divisional Application Statement

[0002] This application is a divisional application of a patent application for invention with international application number PCT / US2017 / 054920, international filing date October 3, 2017, China national phase entry application number 201780069607.7, and invention title "Source Color Volume Information Messaging".

[0003] Cross - Reference to Related Applications

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

[0005] The present invention generally relates 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 "Moving Picture Coding", "Supplemental Enhancement Information" (SEI) in Annex D, and "Video Usability Information" (VUI) in Annex E describes the syntax for providing supplemental SEI and VUI information in an encoded bitstream to enable a decoder to better map decoded samples to a 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 communicating 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 transformation of video content. This metadata can vary scene-by-scene or frame-by-frame. For example, such metadata can assist a decoder in presenting high dynamic range (HDR) and wide color gamut (WCG) data on a display having a color volume smaller than that of the master display for the master source image.

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

[0009] While Appendices D and E of H.265 support many color volume-related metadata, they do not carry all the metadata required 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 [2-4] on how to use SEI or VUI message passing to describe content color volume information were submitted. Some of these proposals were influenced by SMPTE ST.2094 [5], but their scopes were quite different.

[0010] In [2], for the signal content color gamut in 2D, a content-SEI message was 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 rather than the true source color gamut [1]. In [3], it was proposed to associate multiple primary color expressions and spatial regions with the identified source characteristics. In [4], a content color volume SEI message for indicating the color volume occupied by the content was proposed. It uses (x, y, Y) to describe the color coordinates and has multiple slices of luminance Y, where each slice has an associated polygon. These proposals have many drawbacks, such as: providing information rarely used by most display manufacturers may increase a large amount of overhead and may require too much computational overhead. As understood by the present inventor herein, in order to improve existing encoding and decoding schemes, improved techniques for generating and communicating source color volume information are needed.

[0011] The methods described in this section are methods that can be adopted, but not necessarily methods that have been previously envisioned or adopted. Therefore, unless otherwise specified, any method described in this section should not be considered prior art solely by virtue of its inclusion in this section. Similarly, unless otherwise specified, the problems identified with one or more methods should not be considered to have been recognized in any prior art based on this section. Summary of the Invention

[0012] According to some embodiments of the present disclosure, there is provided an apparatus for extracting source color volume information of an input bitstream from a supplementary enhancement information (SEI) message. The apparatus includes a processor, wherein the processor is configured to: receive a first SEI message transmission variable that is part of the source color volume information in the SEI message; if the first SEI message transmission variable matches a first predetermined value, then for each of one or more primary colors, extract first x and y chromaticity coordinates from the source color volume information in the SEI message, wherein the first x and y chromaticity coordinates of the one or more primary colors define a maximum 2D color gamut of the source color volume; extract a minimum luminance value, a maximum luminance value, and an average luminance value from the source color volume information in the SEI message, wherein the minimum luminance value, the maximum luminance value, and the average luminance value are for valid regions of one or more decoded pictures in the input bitstream; and generate 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, there is provided an apparatus for generating an encoded video bitstream. The apparatus includes a processor, wherein the processor is configured to: obtain 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 includes: a supplementary enhancement information (SEI) message, wherein the source color volume information in the SEI message includes: a first SEI message transmission variable that indicates a first set of x and y chromaticity coordinates of one or more primary colors for identifying a maximum 2D color gamut of the source color volume of the data in the bitstream; and a minimum luminance value, a maximum luminance value, and an average luminance value of the data in the bitstream, wherein the minimum luminance value, the maximum luminance value, and the average luminance value are for valid regions of one or more decoded pictures in the bitstream; and encode the data representing the one or more picture frames in the compressed format to generate the encoded video bitstream. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments of the present invention are shown by way of example and not limitation in the figures, and like reference numerals refer to like elements, and in the figures:

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

[0016] Figure 2 An example of a "maximum" possible color volume diagram of a video container format is depicted;

[0017] Figure 3A An example of a source content color gamut within a container color volume is depicted;

[0018] Figure 3B and Figure 3C depicts an example of a 2D slice of the container and source color volume at a specific luminance (Y) value; and

[0019] Figure 4 depicts an example process for extracting source color volume information from SEI messaging in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0020] Techniques for communicating source color volume information using SEI messaging are described herein. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It is apparent, however, that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are not described in detail to avoid obscuring, obfuscating, or confusing the present invention.

[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 that is 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 x chromaticity coordinates and y chromaticity coordinates 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 that is 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 x chromaticity coordinates and y chromaticity coordinates 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 1Depicts an example process of a video delivery pipeline (100), which shows various stages from video capture to video content display. An image generation block (105) is used to capture or generate a sequence of video frames (102). The video frames (102) can 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) can 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) can include adjusting or modifying the color or brightness in a specific region of the image to enhance the image quality or achieve a specific look of the image according to 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.) can 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 monitor (125) (also referred to as the "targeted monitor" since the production studio has optimized the video for it).

[0026] In some embodiments, prior to video encoding (120), the video content can be analyzed to extract source color volume metadata (119) as defined, for example, in SMPTE ST 2094-1 [5] or as will be defined later in the present invention. Such metadata can also define the characteristics of the targeted monitor (e.g., the reference monitor (125)) and color remapping information so that downstream receivers can present the decoded data in the best possible way.

[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 an encoding block (120) in an appropriate color format (e.g., 10-bit YCbCr, ICtCp, etc. with 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 audio and video encoders 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) with a higher dynamic range than the base layer alone. The signal (122) (i.e., the output bitstream from the encoder (120)) can also include metadata (119) and additional encoding-related metadata such as prediction parameters and other data to assist the 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 destination) display (150) can have characteristics that are completely different from those of the reference (or target) display (125). For example but not limited to, the reference display (125) can be a 1,000 nit display, while the receiver display can be a 500 nit display. In such a case, a display management module (140) can 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 with a first dynamic range (e.g., 1,000 nits) to a display with a second dynamic range (e.g., 500 nits). The display management unit (140) can 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 luminance range of the target (or reference) display (e.g., 125) and the source data can be used on 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 2depicts an example of the "maximum" possible color volume (also referred to as the "container color volume") of a predefined container format (e.g., BT.2020). Such a volume can be composed of two-dimensional (2D) gamut primaries, a white point chromaticity (e.g., D65), a maximum luminance value (e.g., L 最大 = 4,000 nits), and a minimum luminance value (e.g., 0.005 nits). This figure indicates the boundary of the maximum possible color volume for all colors in the source video content.

[0031] In practice, as depicted by the darker "cloud" (305) in Figure 3A or the darker regions (305) in Figure 3B and Figure 3C , the source color volume for the 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). Since the actual color volume (305) has a very irregular shape, transmitting such source color volume information for each frame or entire scene would require a large amount of information. For example, in an embodiment, gamut information can be signaled for multiple luminance values (e.g., 0.1, 1, 10, etc.). Then the question becomes: how many luminance values and which are the most important luminance values? It is also necessary to consider not only the required overhead of such information on the encoded 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 convey the minimum and maximum luminance values in the source content, as understood by the inventors, conveying the average luminance (or midpoint luminance) is also valuable to the receiver. These three values together 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 gamut occupied by the source (e.g., the source color volume); b) the maximum, minimum, and average luminance of the source; and c) optionally, the (2D) gamut for the slicing of these three luminance values (e.g., see Figure 3B and Figure 3C ). It is assumed that the white points 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, e.g., frame-by-frame or scene-by-scene. Figure 3B and Figure 3C depict examples of 2D slices of the source color volume (305) and the container color volume (310) at a particular luminance (Y) value. In Figure 3B , the 2D slice is Y = 84 nits, and in Figure 3CIn this case, the 2D slice is Y = 246 nits. For illustrative purposes only, a chromaticity (rgb) triangle is provided around the source color volume (305) and within the container RGB space. The encoder can choose to define a smaller or larger such region and communicate it to the receiver.

[0033] Table 1 depicts an example of source color volume SEI message transmission following 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 of the primary colors as defined in ISO 11664-1 (see also ISO 11664-3 and CIE 15), and uses red, green, and blue primary colors. Other types of primary colors can also be used, such as four, five, or six, or other polygon-based primary color representations. For the maximum actual 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 the current source content can reach the P3 color space, but it will take some time to reach the BT.2020 / 2010 color (the "DCI-P3" is defined in SMPTE EG 432-1 and SMPTE RP 431-2). Therefore, in those cases where the source color gamut is less than or equal to P3, or equal to the BT.2020 / 2010 primary colors, Table E.3 can be used; however, for sources with a color gamut greater than P3 but less than BT.2020 / 2010, an explicit signal representation of the color gamut may be required. The luminance value is specified using the absolute value of the luminance value in nits (cd / m 2 )). Alternatively, to save bits, the luminance value can also be encoded using a non-linear representation, such as a value encoded according to the inverse EOTF of SMPTE ST 2084. It is optional to have the color gamut information corresponding to the maximum luminance value, the minimum luminance value, and the average (mid) luminance value to allow applications to reduce the 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 luminance or chromaticity preprocessing. For example, it should describe the source color volume before any chromaticity subsampling process (e.g., from 4:4:4 to 4:2:0) or bit depth conversion process (e.g., from 12b to 10b), because chromaticity subsampling or bit depth conversion will modify the color volume information. 2) The source color gamut is usually different from the container primary colors indicated in Appendix E of H.265 (e.g., Table E.3). 3) The source color volume is usually different from the master display color volume, which can be indicated by the master display color volume SEI message.

[0035] In an exemplary embodiment, the parameters (or variables) in Table 1 and the coding semantics can be described as follows:

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

[0037] source_colour_volume_cancel_flag (source_color_volume_cancel_flag) equal to 1 indicates that the source color volume SEI message cancels the retention of any previous source color volume SEI message applied to the current layer in output order. source_colour_volume_cancel_flag equal to 0 indicates that the source color volume follows.

[0038] source_colour_volume_persistence_flag (source_color_volume_persistence_flag) specifies the retention of the source color volume SEI message for the current layer. source_colour_volume_persistence_flag equal to 0 specifies that the source color volume information is applied only to the current picture.

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

[0040] - The start of a new coded layer video sequence (CLVS) for the current layer

[0041] - The end of the bitstream

[0042] - Output the picture picB in the current layer in the output access unit. The picture picB contains source colour volume SEI messages that have the same value of source_colour_volume_id and are applicable to the current layer. For this 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 calling the decoding process for the picture order count of picB.

[0043] source_colour_primaries (source primary colours) has the same semantics as specified in Clause E.3.1 of the colour_primaries syntax element, except that colour_primaries in Clause E.3.1 signals the container source primaries, while source_colour_primaries signals the primaries actually occupied by the source content.

[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] (source primary x[c]) and source_primaries_y[c] (source primary y[c]) respectively specify the normalized x chromaticity coordinate and y chromaticity coordinate of the primary colour component c of the source content according to the CIE 1931 definition of x and y as specified in ISO 11664-1 (see also ISO 11664-3 and CIE 15), with an increment of 0.00002. To describe source content using red, green, and blue primaries, it is recommended that the 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 Appendix E and Table E.3). The values of source_primaries_x[c] and source_primaries_y[c] should be in the range from 0 to 50,000 (including the endpoints).

[0046] max_source_luminance (maximum source luminance), min_source_luminance (minimum source luminance), and avg_source_luminance (average source luminance) respectively specify the nominal maximum luminance, minimum luminance, and average luminance of the source in units of 0.0001 candela per square meter (nits). min_source_luminance shall be less than avg_source_luminance, and avg_source_luminance shall be less than max_source_luminance.

[0047] luminance_colour_primaries_info_present_flag being equal to 1 specifies the presence of the syntax elements luminance_primaries_x and luminance_primaries_y, and luminance_colour_primaries_info_present_flag being equal to 0 specifies the absence of the syntax elements luminance_primaries_x and luminance_primaries_y.

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

[0049] Table 1 provides the minimum information that is considered a useful representation of the source color volume. In another embodiment, it may be decided to define additional details, such as multiple primary color expressions [3], or a description of the primary colors for more than three luminance (Y) slices, where each slice has an associated polygon.

[0050] Table 1: Example of the SEI message transmission syntax for the source color volume

[0051]

[0052]

[0053] Figure 4 An example process for extracting color volume information of a video source using SEI message transmission according to an embodiment is depicted. First (405), the decoder may detect whether there is a first SEI message transmission 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 may 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 may 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 message transmission parameter (e.g., source_colour_primaries), the decoder may check whether the metadata clearly defines the color volume that the source data content actually occupies. 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 primary colors with 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 does not exist (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 may use the source color volume data during its display management process (e.g., 140). In an example, the display management may include two steps: tone mapping and gamut mapping. The minimum luminance value, the middle luminance value, and the maximum luminance value may be used to generate a tone mapping curve as described in [6-7]. The maximum RGB gamut and the slice RGB gamut may be used to perform gamut mapping.

[0055] Consideration of the active region

[0056] In some embodiments, it may be beneficial to define the active region as part of the metadata related to the source color volume. For example, when encoding a video in a letterbox format, the encoder and decoder should not include the black letterbox area 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" (e.g., pillarboxing, windowboxing, and letterboxing) of the frames in a video sequence can significantly improve the overall output picture quality. Although letterbox detection can be implemented by the decoder, thereby reducing the signaling overhead for defining the active picture region, 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 message transmission with active region signaling according to an embodiment.

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

[0058]

[0059]

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

[0061] Semantic 1. In an embodiment, the active region is specified relative to the decoded picture before cropping and output within the compliance window. Then, the active region parameters can be interpreted as follows:

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

[0063] active_region_left_offset (effective region left offset), active_region_right_offset (effective region right offset), active_region_top_offset (effective region top offset), and active_region_bottom_offset (effective region bottom offset) specify the effective rectangular region. When active_region_flag is equal to 0, it is inferred that the values of active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset are equal to 0.

[0064] The effective region is defined using the horizontal picture coordinates from SubWidthC * active_region_left_offset to pic_width_in_luma_samples - (SubWidthC * active_region_right_offset + 1) and the vertical picture coordinates from SubHeightC * active_region_top_offset to pic_height_in_luma_samples - (SubHeightC * active_region_bottom_offset + 1), including the endpoints. The value of SubWidthC * (active_region_left_offset + active_region_right_offset) should be less than pic_width_in_luma_samples, and the value of SubHeightC * (active_region_top_offset + active_region_bottom_offset) should be less than pic_height_in_luma_samples.

[0065] Semantics 2. In an embodiment, the effective region offset values are defined with respect to the final output picture to be displayed, so the consistency window parameters need to be considered. Then, the effective region parameters can be interpreted as follows:

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

[0067] active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset specify a valid rectangular region. When active_region_flag is equal to 0, it is inferred that the values of active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset are equal to 0.

[0068] Define the valid region using horizontal picture 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 picture 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 hereby incorporated 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 [Series H: Audiovisual and Multimedia systems, Infrastructure of audiovisual services – Coding of moving video, High efficiency video coding]", ITU, October 2014.

[0073] [2] H.M. Oh et al., "Content colour gamut SEI message [Content colour gamut SEI message]", JCTVC-X0040, May 2016, Geneva, CH.

[0074] [3] A.M. Tourapis, "Improvements to the Effective Colour Volume SEI [Improvements to the Effective Colour Volume SEI]", JCTVC-X0052, May 2016, Geneva, CH.

[0075] [4] A.K. Ramasubramonian, "Content colour volume SEI message [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 [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 [Dynamic Metadata for Color Volume Transform – Application #1]", SMPTE, May 18, 2016.

[0078] [7] R. Atkins et al., U.S. Patent Publication US2016 / 0005349, "Display management for high dynamic range video".

[0079] Example Computer System Implementations

[0080] Embodiments of the present invention may be implemented using a computer system, a system configured with electronic circuits and components, an integrated circuit (IC) device (such as a microcontroller, a field-programmable gate array (FPGA), or other configurable or programmable logic device (PLD), a discrete-time or digital signal processor (DSP), an application-specific IC (ASIC)), and / or an apparatus including one or more such systems, devices, or components. The computer and / or IC may execute, control, or implement 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 the various parameters or values related to the processes described herein. Image and video embodiments may be implemented in hardware, software, firmware, and their various combinations.

[0081] Certain embodiments of the present invention include a computer processor that executes software instructions that cause the processor to perform the methods of the present invention. For example, one or more processors in a display, an encoder, a set-top box, a transcoder, etc. 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 processor. The present invention may 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 methods of the present invention. The program product according to the present invention may take any of various forms. The program product may include, for example, a physical medium, such as a magnetic data storage medium including a floppy disk, a hard disk drive, an optical data storage medium including a CD ROM, a DVD, an electronic data storage medium including a ROM, a flash RAM, etc. The computer-readable signals on the program product may optionally be compressed or encrypted.

[0082] In the case of the above-mentioned components (e.g., software modules, processors, components, devices, circuits, etc.), unless otherwise specified, a reference to such a component (including a reference to a "device") shall be construed to include any equivalent (e.g., functionally equivalent) of the component that performs the function of the described component, including components that are not structurally equivalent to the disclosed structure that performs the function in the exemplary embodiments illustrated in the present invention.

[0083] Equivalents, Extensions, Substitutions, and Miscellaneous

[0084] An example embodiment involving the use of SEI messaging to convey source color volume information has been described as such. In the foregoing specification, embodiments of the present invention have been described with reference to numerous specific details, which may vary according to the implementation. Therefore, the only and exclusive indication of the present invention, as intended by the applicant, is the claims issued in this specific form from this application, including any subsequent amendments. Any definition explicitly set forth herein for terms included in such claims shall govern the meaning of such terms as used in the claims. Accordingly, limitations, elements, characteristics, features, advantages, or attributes not explicitly recited in the claims should not in any way limit the scope of such claims. Therefore, the specification and drawings should be regarded as illustrative rather than having a limiting meaning.

Claims

1. A method for extracting source color volume information of an input bitstream from a supplementary enhancement information (SEI) message in a decoder, the method being executed on a processor, the method comprising: Receiving an SEI message, the SEI message including one or more flags and one or more source color SEI parameters, the one or more flags including a source color primary flag, and the one or more source color SEI parameters including a primary component parameter and a luminance value parameter; If the source color primary flag indicates the x and y chromaticity coordinates of one or more primary color components, then for the primary color component c , extract from the primary color component parameters x and y chromaticity coordinates, where the x and y chromaticity coordinates respectively define the normalized c and x and y chromaticity coordinates of the primary color component of the input bitstream; and Extracting a minimum luminance value, a maximum luminance value, and an average luminance value from the luminance value parameter, wherein the minimum luminance value, the maximum luminance value, and the average luminance value are for a picture in one or more decoded pictures in the input bitstream or a valid region of one or more decoded pictures in the input bitstream; Wherein the one or more flags further include a source color volume retention flag for specifying retention of the source color volume SEI message of the current layer, wherein: The source color volume retention flag being equal to 0 specifies that the source color volume information applies only to the current picture; and The source color volume retention flag being equal to 1 specifies that the source color volume information persists in the current layer in output order until a set condition occurs.

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

3. The method according to claim 1, wherein To describe a color volume using red, green, and blue primary colors, c = 0 corresponds to the green primary color, c = 1 corresponds to the blue primary color, and c = 2 corresponds to the red primary color.

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