EA048261B1 - MESSAGING WITH INFORMATION ABOUT THE ORIGINAL COLOR VOLUME - Google Patents

Abstract

The invention describes methods for communicating source color volume information in an encoded bitstream using SEI messaging. Such data includes at least the minimum, maximum, and average luminance values in the source data, plus optional data that may include x- and y-coordinates of the color volume for the input primary colors (e.g., red, green, and blue) in the source data, and x- and y-coordinates of the color for the primary colors corresponding to the minimum, average, and maximum luminance values in the source data. Message data signaling the active region in each picture may also be included.

Description

Cross-reference to related applications

This application claims priority from 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, both of which are incorporated herein by reference in their entireties.

Field of technology

The invention relates generally to images. In particular, an embodiment of the present invention relates to communicating and processing information about the color volume of a source.

State of the art

ITU-T Recommendation H.265 [1] (also known as HEVC) for the coding of moving video in Annex D Supplemental enhancement information (SEI) and Annex E Video usability information (VUI) describes a syntax for providing additional SEI and VUI information in the coded bitstream to allow a decoder to better display decoded samples on a display.

In parallel with the MPEG/ITU standardization processes, the Society of Motion Picture and Television Engineers (SMPTE) has also defined a number of Recommendations related to the reporting of metadata related to color volume information for both the source video and the target display. For example, the SMPTE ST 2094 set of documents (e.g., [5] and [6]) defines metadata for use in color volume transformations of video content. This metadata may vary from scene to scene or frame to frame. For example, such metadata may help a decoder present high dynamic range (HDR) and wide color gamut (WCG) content on a display with a smaller color volume than the mastering display that was used to master the source images.

As used in this document, metadata refers to auxiliary information that is transmitted as part of the encoded bitstream and helps the decoder visualize the decoded image. Such metadata may include, but is not limited to, color space and gamut information, prediction parameters, reference display parameters, and auxiliary signal parameters as described in this document.

While H.265 Annexes D and E support some color volume related data, they do not carry all the metadata required to most effectively manage a display of HDR content. At the July 2016 Joint Task Force on Video Coding (JCT-VC) meeting in Geneva, three proposals [2-4] were presented on how to describe content color volume information using SEI or VUI messaging. Some of these proposals were influenced by SMPTE ST. 2094 [5], but they differed significantly in scope.

In [2], a content SEI message is proposed to signal the 2D color gamut of the content, which describes the actual color distribution of the video content. In VUI, the colour_primaries variable is used to indicate the color gamut of a container instead of the true source color gamut [1]. In [3], multiple primaries and spatial regions 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) color coordinate description and has Y luma slices with associated polygons for each slice. These proposals have several drawbacks, such as providing information that is of little use to most display manufacturers, may add significant overhead, and may be computationally expensive to generate. To improve upon existing encoding and decoding schemes, as understood by the inventors herein, improved techniques for generating and reporting source color volume information are needed.

The approaches described in this section are approaches that can be implemented, but are not necessarily approaches that have been previously conceived or implemented. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section is defined as prior art solely by virtue of being included in this section. Similarly, it should not be assumed that the problems identified with respect to one or more approaches have been recognized in any prior art based on this section, unless otherwise indicated.

Brief description of the drawings

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

Fig. 1 depicts an exemplary process for a video delivery channel in accordance with an embodiment of the present invention;

Fig. 2 shows an example of the largest possible color volume graph for a video container format;

- 1 048261 Fig. 3A depicts an example of the coverage of the original content in the color volume container;

Fig. 3B and Fig. 3C depict examples of 2D slices of the container and the original color volume at specific brightness (Y) values;

Fig. 4 depicts an example process for extracting source color volume information from SEI message exchange in accordance with an embodiment of the present invention.

Description of exemplary embodiments

This document describes techniques for exchanging source color volume information messages using SEI messaging. 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 will be 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 exhaustive detail in order to avoid unnecessarily obscuring or confusing the present invention.

General idea

Exemplary embodiments described in this document 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 corresponds to a first predetermined value, then for one or more primary colors, it generates x and y chromaticity coordinates for the one or more primary colors based on the source color volume information in the input bitstream. It generates a minimum, maximum, and average brightness 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 corresponds to a second predetermined value, then for one or more primary colors, it generates x and y chromaticity coordinates for the one or more primary colors corresponding to minimum, maximum, and average luminance values based on the source color volume information.

Examples of Original Color Volume Messaging

Fig. 1 shows an exemplary process of a video delivery channel (100), showing various stages from video capture to display of video content. A sequence of video frames (102) is captured or generated using an image generation unit (105). The video frames (102) can be captured digitally (e.g., by means of 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 using a film camera. 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 on the unit (110) for post-production editing.

Post-production editing (110) may involve adjusting and modifying colors or brightness in specific areas of an image to improve image quality or to achieve a specific look for the image in accordance with the artistic intent of the video creator. This is sometimes referred to as color timing or color correction. Other editing (e.g., scene selection and ordering, image cropping, adding computer-generated visual effects, etc.) may be performed in the unit (110) to produce a final production version (112) for distribution. During post-production editing (110), video images are viewed on a reference display (125) (which is also referred to as a target display because the studio optimizes the video for it).

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

Following post-production (110) and analysis (115) of the original color volume, the final production video data (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 an encoding unit (120) for downstream delivery to decoding and playback devices such as televisions, set-top boxes, movie theaters, and the like. In some embodiments, the encoding unit (120) may include audio and video encoders such as those

- 2 048261 are defined by ATSC, DVB, DVD, Blu-Ray and other delivery formats to generate an encoded bitstream (122). The encoded bitstream (122) may be represented by an encoded video bitstream with a single layer or a multi-layer bitstream. For example, in a multi-layer bitstream, the signal (122) may include a base layer (say 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 with a higher dynamic range than that of the base layer alone (for example, a 12-bit HDR signal). The signal (122), 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 help the decoder better reconstruct the HDR signal.

In the receiver, the coded bit stream (122) is decoded by the decoding unit (130) to generate a decoded signal (132) and associated metadata (119). The display (150) of the receiver (or target) may have characteristics that are completely different from the reference (or target) display (125). For example, without limitation, the reference display (125) may be a display with 1000 nits, while the display of the receiver may be a display with 500 nits. In such a case, the display management module (140) may be used to map the dynamic range of the decoded signal (132) to the characteristics of the display (150) of the receiver by generating a signal (142) mapped for the display. As used in this document, the term display management refers to processing (e.g., tone and gamut mapping) that is required to display an input video signal of a first dynamic range (e.g., 1000 nits) on a display of a second dynamic range (e.g., 500 nits). The display management unit (140) may take into account metadata (119) to improve the quality of the output video on the display (150). For example, as shown in document [7], information regarding the luminance range of the target (or reference) display (e.g., 125) and the original data may be used at the receiver to better display the dynamic range of the video content on the receiver display (e.g., 150).

Information about color volume

Fig. 2 shows an example of the largest possible color volume of a predefined container format (e.g., BT.202 0) (may also be referred to as the container color volume). Such a volume may be created by two-dimensional (2D) gamut primaries, a white point chromaticity (e.g., D65), a maximum luminance value (e.g., Lmax=4000 nits), and a minimum luminance value (e.g., 0.005 nits). Such a graph indicates the largest possible color volume boundaries for all colors in the original video content.

In practice, as shown by the dark cloud (305) in Fig. 3A or the dark areas (305) in Fig. 3B and Fig. 3C, the original color volume of the source content (e.g. 112) for a particular frame or even the entire scene may be significantly smaller than the largest possible color volume (310). Since the actual color volume (305) has a very irregular shape, then transmitting such information about the original color volume for each frame or the entire scene requires a lot of information. For example, in an embodiment, it is possible to signal the color gamut information for several luminance values (say at 0.1, 1, 10, etc.). The question then arises: how many and which luminance values are most important? Also, it is necessary to take into account not only the required overhead for such information in the encoded bitstream, but also the complexity of generating such content at the encoder and/or recreating the color volume information at the decoder.

While reporting the minimum and maximum luminance values in the source content is important, as the inventors understand, reporting the average luminance (or median luminance) is also useful for the receiver. These three values together can help generate an acceptable tone curve for display rendering. The present invention proposes to signal the following metadata to describe the source color volume: a) the largest 2D color gamut that the source occupies (e.g., the source color volume); b) the maximum minimum and average source luminance; and c) optionally, a sliced (2D) color gamut for those three luminance values (e.g., see Figs. 3B and 3C). It is assumed that the white points of the container primary color and the source content primary color are the same, so there is no reason to re-transmit such information. This information can be updated as needed, e.g., on a per-frame or per-scene basis. Fig. 3B and Fig. 3C illustrate examples of 2D slices of the original color volume (305) and the container color volume (310) at specific luminance (Y) 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 the original color volume (305) and within the container RGB space are provided for illustrative purposes only. An encoder may choose to define and report smaller or larger such areas to a receiver.

Table 1 shows an example of the exchange of SEI messages of the original color volume according to an embodiment that adheres to the nomenclature and syntax of the H.265 specification. The description of the primary colors adheres to the CIE 1931 definition of the (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 the red, green and blue primaries. Other types of primaries may also be used.

- 3 048261 primary colors, such as based on four, five, or six colors, or other polygon-based representation of the primary colors. For the largest actual color gamut in the source content, in a non-limiting embodiment, the syntax is similar to the definition of the parameter (or variable) colour_primaries, which is defined in section E.3.1 for Table E.3 of the H.265 specification.

It is considered that current source content can reach the P3 color space, but will take some time to reach the BT. 2020/2010 colors (DCI-P3 is defined in SMPTE EG 432-1 and SMPTE RP 431-2). Therefore, in cases where the source color gamut is less than or equal to P3 or equal to the BT. 2020/2010 primaries, Table E.3 can be used; however, for sources whose color gamut is greater than P3 but less than BT. 2020/2010, explicit signaling of the color volume may be required. Luminance values are specified using their absolute value in nits (cd/ ^m2 ). Alternatively, to save bits, luminance values can also be encoded using a non-linear representation, such as values encoded according to the inverse EOTF of SMPTE ST 2084. The gamut information corresponding to the max, min, and mid luminance values is made optional, allowing applications to reduce metadata costs if necessary.

Notes: In the preferred embodiment: 1) the source color volume metadata shall describe the source color volume in its original form, before any luma or chroma pre-processing. For example, it shall describe the source color volume before any chroma downsampling process (e.g., from 4:4:4 to 4:2:0) or bit depth conversion process (e.g., from 12-bit to 10-bit), since chroma downsampling or bit depth conversion will modify the color volume information; 2) the source color gamut is typically different from the container primaries, which are specified 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 specified by the mastering display color volume SEI messages.

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

source_colour_volume_id contains an identification number that may be used to identify the destination of the source colour volume. The value of source_colour_volume_id shall be in the range 0 to 232-2, inclusive. source_colour_volume_id values from 0 to 255 and from 512 to ^231-1 may be used as defined by the application. source_colour_volume_id values 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 all Colour Mapping Modification Information SEI messages containing a source_colour_volume_id value in the range 256 to 511, inclusive, or in the range ²³¹ to 232-2, inclusive, and bitstreams shall not contain such values;

source_colour_volume_cancel_flag equal to 1 indicates that the source color volume SEI message cancels the persistence of any previous source color volume SEI message in the output queue that applies to the current layer. source_colour_volume_cancel_flag equal to 0 indicates that the source color volume is not deviated from;

source_colour_volume_persistence_flag specifies whether the source color volume SEI message persists for the current layer. source_colour_volume_persistence_flag equal to 0 indicates that the source color volume information applies only to the current image.

Let picA be the current picture, source_colour_volume_persistence_flag equal to 1 indicates that the source colour volume is preserved for the current layer in the output queue until any of the following conditions becomes true:

a new coded layer video sequence (CLVS) at the current layer begins, the bitstream ends, picture picB at the current layer in the access unit is output, containing a source color volume SEI message with the same source_colour_volume_id value and applicable to the current layer, for which PicOrderCnt(picB) is greater than PicOrderCnt(picA), where PicOrderCnt(picB) and PicOrderCnt(picA) are the values of PicOrderCntVal of picB and pica respectively, immediately after the decoding process is called for the picture order counter for picB, source_colour_primaries has exactly the same semantics as specified in E.3.1 for the colour_primaries syntax element, except that colour_primaries in E.3.1 signals the source primaries of the container, and source_colour_primaries signals the primaries that the source content actually occupies.

When the value of source_colour_primaries is 2, source_colour_primaries is explicitly specified by the syntax source_primaries_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 c primary color component of the source content in increments of 0.00002 per

- 4 048261 according to the CIE 1931 definition of x and y, as specified in ISO 11664-1 (see also ISO 11664-3 and CIE 15). For describing source content that uses the red, green, and blue primaries, it is assumed that an index value of 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 Appendix E and Table E.3). The values of source_primaries_x[c] and source_primaries_y[c] shall be in the range 0 to 50000, 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 meter (nits).

min_source_luminance must be less than avg_source_luminance, and avg_source_luminance must be less than max_source_luminance.

luminance_colour_primaries_info_present_flag equal to 1 indicates that the syntax elements luminance_primaries_x and luminance_primaries_y are present, luminance_colour_primaries_info_present_flag equal to 0 indicates that the syntax elements luminance_primaries_x and luminance_primaries_y are not present.

luminance_primaries_x[i][c] and luminance_primaries_y[i][c] specify the normalized x and y chromaticity coordinates, respectively, of the c primary color component of the source content at one nominal luminance in increments of 0.00002 according to the CIE 1931 definition of x and y as specified in ISO 11664-1 (see also ISO 11664-3 and CIE 15). For describing the source luminance of the content, index values of 0, 1, and 2 shall refer to max_source_luminance, min_source_luminance, and avg_source_luminance, respectively. To describe source content that uses red, green, and blue primaries, it is assumed that an index value of c equal to 0 should suggest a green primary, c equal to 1 should suggest a blue primary, and c equal to 2 should correspond to a 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 50000, inclusive.

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

Table 1

Sample syntax for exchanging SEI source color volume messages

source color volume (payloadsize) { Descriptor source colour volume id ue (v) source color volume cancel flag u(l) if ( !source color volume cancel flag ) {

- 5 048261

source color volume persistence flag u(l) source colour primaries u(8) if (source color primaries == 2) { for ( c=0; c < 3; c++ ) { source primaries x[ c ] u (16) source primaries y[ c ] u (16) } } max source luminance u (32) min source luminance u (32) avg source luminance u (32) luminance color primaries info present flag u(l) if (luminance color 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) } } } } }

Fig. 4 shows an example process for extracting color volume information for a video source using SEI messaging in accordance with an embodiment. First (405), the decoder may detect whether a first variable of the SEI messaging indicating an identification number (ID) of the source color volume information (e.g., source_colour_volume_id) is present. Then, given the presence of such a variable, the decoder may check (step 407) whether its value is in an allowed range. If this is an invalid value, then the processing is stopped (step 409). If this is a valid value, then in step (410), as shown in Table 1, the decoder may read additional flags related to the persistence of the first variable across the bitstream (e.g., see the syntax elements for source_colour_volume_cancel_flag and source_colour_volume_persistence_flag). In step (412), via the second parameter of the SEI messaging (e.g., source_colour_primaries), the decoder may check whether the metadata explicitly defines a color volume that is actually occupied by the original data content. If this is true (e.g., source_colour_primaries=2), then in step (420), the (x, y) chromaticity coordinates of the color for each primary color (e.g., red, green, and blue) are read, otherwise in step (425), the decoder extracts the minimum, maximum, and average luminance values. Optionally, the SEI messaging may also determine the (x, y) chromaticity coordinates of the color corresponding to the primary colors of the min, mid, and max luminance values determined earlier. In an embodiment, this may be indicated by the third parameter (e.g., luminance_colour_primaries_info_present_flag=1). If such information is not present (step 430), then the process terminates (409), otherwise (at step 435) the decoder extracts (x, y) chromaticity coordinates of the color for the primary colors for each of the min, mid and max brightness values.

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, display management may include two stages: tone mapping and gamut mapping. The min, mid, and max luminance values may be used to generate a tone mapping curve as described in [6-7]. The maximum RGB gamut and the sliced RGB gamut may be used to perform gamut mapping.

Active Area Accounting

In some embodiments, it may be advantageous to define the active region as part of the metadata related to the original color volume. For example, when video is encoded in a letterboxed format, encoders and decoders should not include the black areas of the letterbox when calculating the luminance and chrominance characteristics of each video frame (e.g., minimum, maximum, and average luminance). Experimental results have shown that taking into account

- 6 048261 framing or matting (e.g., pillarboxing, windowboxing, and letterboxing) of frames in a video sequence can significantly improve the overall output quality of the picture. Although letterboxing detection can be implemented by the decoder, thereby reducing the signaling overhead to determine the active region of the picture, in an embodiment such signaling can be signaled explicitly to support decoders with low computational complexity. Table 2 shows an example of an exchange of source color volume SEI messages with active region signaling according to an embodiment.

Table 2

Example syntax of the SEI message of the original color volume with active region signaling

source color volume (payloadsize) { Descriptor source colour volume id ue (v) source colour volume cancel flag u(l) if ( !source color volume cancel flag ) { source color 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) } } max source luminance u (32) min source luminance u (32) avg source luminance u (32) luminance colour primaries info present flag u(l) if (luminance_colour_primary es_info_present_flag) { for( i=0; i <= 3; iff ) { for ( c=0; c < 3; c++ ) { luminance_primaries_x[ i ][ c ] u (16) luminance primaries y[ i ][ c ] u (16) } } } active_region_flag u(l) if (active region flag) { active region left offset ue (v) active region right offset ue (v) active region top offset ue (v) active region bottom offset ue (v) } } }

Table 2 is an extended version of Table 1 and takes into account two different semantics for defining an active region.

Semantics 1. In an embodiment, the active region is specified relative to the decoded picture before the compatibility window is cropped and output. Then the parameters of the active region can be interpreted as follows:

active_region_flag equal to 1 indicates that the active region offset parameters follow in the source color volume information SEI message. active_region_flag equal to 0 indicates that the active region offset parameters are not present.

active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset specify the active rectangular region. When active_region_flag is 0, the values of active_region_left_offset,

- 7 048261 active_region_right_offset, active_region_top_offset and active_region_bottom_offset are assumed to be 0.

The active region is defined by horizontal image coordinates from SubWidthC * active_region_lef_offset to pic_width_in_luma_samples - (SubWidthC * active_region_right_offset+1) and vertical image 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) must be less than pic_width_in_luma_samples, and the value of SubHeightC * (active_region_top_offset+active_region_bottom_offset) must be less than pic_height_in_luma_samples.

Semantics 2. In an embodiment, the active region offset values are determined relative to the final output image for display, so the compatibility window parameters must be taken into account. Then the active region parameters can be interpreted as follows:

active_region_flag equal to 1 indicates that the active region offset parameters follow in the source color volume information SEI message. active_region_flag equal to 0 indicates that the active region offset parameters are not present.

active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset specify the active rectangular region. When active_region_flag is 0, the values of active_region_left_offset, active_region_right_offset, active_region_top_offset, and active_region_bottom_offset are assumed to be 0.

The active region is defined by horizontal coordinates of the image 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 coordinates of the image from active_region_top_offset+SubHeightC * conf_win_top_offset to CtbSizeY * PicHeightInCtbsY - SubHeightC * conf_win_bottom_offset - active_region_bottom_offset - 1, inclusive.

The value of (active_region_left_offset+active_region_right_offset) must 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) must be less than CtbSizeY * PicHeightInCtbsY SubHeightC * (conf_win_bottom_offset+conf_win_top_offset).

Each document in the list of references below is incorporated in its entirety into this disclosure by reference.

List of references

1. Rec. 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

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

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

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

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., US Patent Publication US 2016/0005349, Display management for high dynamic range video.

Sample implementation of a computer system

Embodiments of the present invention may be implemented using a computer system, systems configured in electronic circuitry or 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 a device that includes 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 a variety of parameters or values that relate to the processes described herein. Image and video embodiments may be implemented in hardware, software, firmware, and various combinations thereof.

Certain implementations of the invention comprise computer processors that execute software instructions that cause the processors to perform a method of the invention. For example, one or more processors in a display, encoder, set-top box, transcoder, or the like may implement methods relating to communicating information about

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Claims (4)

original color volume, using SEI messaging as described above by executing software instructions in a program memory accessible to processors. The invention may also be provided in the form of a software product. The software product may comprise any non-transitory storage medium that carries a set of computer-readable signals containing instructions that, when executed by a data processor, cause the data processor to perform the method of the invention. Software products according to the invention may be in any of a wide variety of forms. The software product may comprise, for example, physical storage media such as magnetic storage media including floppy disks, hard disk drives, optical storage media including CD ROM, DVD, electronic storage media including ROM, flash RAM or the like. The computer-readable signals in the software product may be optionally compressed or encrypted. Where a component (e.g., a software module, a processor, a node, a device, a circuit, etc.) is mentioned above, unless otherwise indicated, reference to that component (including a reference to means) shall be interpreted as including as equivalents of that component any component that performs the function of the described component (e.g., that is a functional equivalent), including components that are not structurally equivalent to the disclosed structure that performs the function in the illustrated exemplary embodiments of the invention. Equivalents, extensions, alternatives and more Thus, exemplary embodiments are disclosed that relate to communicating source color volume information using SEI messaging. In the preceding technical description, embodiments of the present invention have been described with reference to specific details that may vary from implementation to implementation. Accordingly, the sole and exclusive indicator of what constitutes an invention and is intended by applicants as an invention is the set of claims that result from this application, in the specific form in which such claims are published, including any subsequent amendment. Any definitions expressly set forth herein for concepts contained in such claims shall determine the meaning of such concepts as used in the claims. Accordingly, no limitation, element, property, feature, advantage or attribute that is not expressly stated in the claims shall in any way limit the scope of the claims. The technical description and the drawings, accordingly, shall be considered in an illustrative and not limiting sense. CLAUSE OF THE INVENTION 1. A method for generating an encoded bit stream, wherein the method comprises obtaining a sequence of video images; encoding one or more video images to generate compressed video images; generating a metadata message indicating information about the original color volume for the compressed video images; and generating an output video bitstream containing the compressed video images and the metadata message, wherein the metadata message contains normalized chromaticity coordinates x and y of one or more primary color components in the coded bitstream and luminance value parameters containing an average luminance value, wherein for one or more coded video images in the bitstream that are encoded in a letterboxed format, the average luminance value relates to an active region of the one or more coded video images in the bitstream that are encoded in a letterboxed format. 2. The method of claim 1, wherein the normalized x and y chromaticity coordinates are specified in increments of 0.00002 in accordance with the CIE 1931 definition of x and y as specified in ISO 11664-1. 3. The method according to claim 1, wherein the metadata message comprises a supplementary extension information (SEI) message. 4. A method for transmitting a video bitstream that is generated by a video encoding device, wherein the method comprises transmitting the bitstream, wherein the video bitstream is characterized by data representing one or more video images in a compressed format, wherein a portion of the data that represents one or more video images in a compressed format contains a metadata message that contains a message variable that indicates the presence of a set of x and y chromaticity coordinates for one or more primary colors for identifying a two-dimensional color gamut of information about the original color volume of data in the video bitstream; and