KR-20260066160-A - Low-dynamic range signaling for image and video coding

Abstract

The present disclosure generally relates to video coding, and in particular to methods and systems for signaling Low Dynamic Range (LDR) in video or image bitstreams. For example, the present disclosure describes implementations of methods for explicitly or implicitly signaling whether LDR is applied and which of the LDRs is applied to a block at various signaling levels.

Inventors

• 자오 신
• 딩, 딩
• 류, 산

Assignees

• 텐센트 아메리카 엘엘씨

Dates

Publication Date

20260512

Application Date

20240628

Priority Date

20240627

Claims (20)

1. As a method for decoding blocks in a bitstream of a video or image, A step of receiving the above bitstream; A step of determining from the bitstream that a Low Dynamic Range (LDR) is applied to the block; and When a low dynamic range is applied to the above block: A step of determining an LDR selected from a group of LDRs to encode the block; The step of decoding the above block to generate reconstructed LDR samples of the above block; and A method comprising the step of generating reconstructed samples from the reconstructed LDR samples according to the selected LDR.
2. A method according to claim 1, wherein the group of LDRs is predefined, and the LDR index is explicitly signaled by an LDR syntax element in the bitstream or implicitly derived from the bitstream.
3. A method according to paragraph 2, wherein each group of the LDRs is predefined as having a sample value range of 2 N , where N is a non-negative integer and represents the bit depth of each group of the LDRs.
4. In paragraph 3, the method wherein the LDR index is explicitly signaled by a value of 7-N.
5. A method according to paragraph 2, wherein the LDR index is explicitly signaled by the LDR syntax element as a high-level syntax in a sequence header, picture header, subpicture header, frame header, slice header, or tile header.
6. A method according to paragraph 2, wherein the LDR index is explicitly signaled as one or more block-level syntaxes by the LDR syntax element.
7. In paragraph 2, the LDR index is signaled in one or more SEI (supplemental enhancement information) messages, and each SEI message includes additional data inserted into the bitstream to convey additional information.
8. A method according to any one of claims 1 to 7, wherein the LDR signaling indicating that the LDR is applied or the LDR applied to the block depends at least on the value of another syntax element within the bitstream.
9. A method according to claim 8, wherein the LDR is applied only when the bitstream is intended for at least machine vision as indicated by the other syntax elements, or where the LDR signaling is present within the bitstream.
10. A method according to claim 8, wherein the LDR is applied only when the quantization parameters of the block are greater than a predefined quantization parameter threshold, or the LDR signaling exists within the bitstream.
11. A method according to claim 8, wherein the LDR is applied only when the picture resolution associated with the block is greater than or less than a predefined resolution value, or the LDR signaling exists within the bitstream.
12. A method according to claim 8, wherein the LDR is applied only when the frame rate associated with the block is greater than or less than a predefined frame rate value, or the LDR signaling exists within the bitstream.
13. A method according to any one of claims 1 to 7, wherein LDRs for different color components of the block are individually signaled in the bitstream.
14. A method according to any one of claims 1 to 7, wherein the LDR is applied and signaled only to the luma component of the block.
15. A method according to any one of claims 1 to 7, wherein the LDR selected to encode the block is implicitly derived based on the coded information of the block.
16. As a method for encoding blocks in a bitstream of a video or image, A step of determining that a Low Dynamic Range (LDR) should be applied to the above block; and When it is determined that a low dynamic range should be applied to the above block: A step of selecting an LDR for encoding the block from among a group of LDRs; A step of processing the block using the selected LDR to generate encoded LDR samples of the block in the bitstream; and A method comprising the steps of determining whether an LDR is applied to the block and explicitly or implicitly signaling the selected LDR in the bitstream.
17. A method according to claim 16, wherein the group of LDRs is predefined and the LDR index is explicitly signaled by the LDR syntax element in the bitstream.
18. In paragraph 17, each group of the above LDRs is predefined as having a sample value range of 2 N , where N is a non-negative integer and represents the bit depth of each group of the above LDRs.
19. In paragraph 18, the method wherein the LDR index is explicitly signaled by a value of 7-N in the bitstream.
20. A method for processing a block of video or image, comprising the step of converting the block into a bitstream, wherein the bitstream is: A step of determining that a Low Dynamic Range (LDR) should be applied to the above block; and When it is determined that a low dynamic range should be applied to the above block: A step of selecting an LDR for encoding the block from among a group of LDRs; A step of processing the block using the selected LDR to generate encoded LDR samples of the block in the bitstream; and Whether an LDR is applied to the above block and the step of explicitly or implicitly signaling the selected LDR in the bitstream The encoded block generated by; and A method comprising at least one syntax element for explicitly or implicitly indicating the above LDR.

Description

Low-dynamic range signaling for image and video coding Integration by citation This application is based on U.S. Regular Patent Application No. 18/756,282 filed June 27, 2024 and U.S. Provisional Patent Application No. 63/542,073 filed October 2, 2023, both of which are titled "Signaling of Low Dynamic Range for Image and Video Coding", and claims the benefit of priority thereto, the entirety of which is incorporated herein by reference. Technology field The present disclosure generally relates to video coding, and in particular to methods and systems for signaling Low Dynamic Range (LDR) in video or image bitstreams. Uncompressed digital video can consist of a series of pictures and may be associated with specific bitrate requirements for storage, data processing, and transmission bandwidth in streaming applications. One objective of video coding and decoding is to reduce redundancy in the uncompressed input video signal through various compression techniques while decreasing signaling overhead. In some applications, the bit depth of some video/image samples may be reduced to further increase coding efficiency. The present disclosure generally relates to video coding, and in particular to methods and systems for signaling Low Dynamic Range (LDR) in video or image bitstreams. For example, the present disclosure describes implementations of methods for explicitly or implicitly signaling whether LDR is applied and which of the LDRs is applied to a block at various signaling levels. In some exemplary implementations, a method for decoding a block in a bitstream of video or image is disclosed. The method may include the step of receiving a bitstream; and the step of determining from the bitstream that a Low Dynamic Range (LDR) is applied to the block. The method may further include the step of determining, when a Low Dynamic Range is applied to the block: an LDR selected from a group of LDRs to encode the block; decoding the block to generate reconstructed LDR samples of the block; and generating reconstructed samples from the LDR samples reconstructed according to the selected LDR. In the exemplary implementations above, groups of LDRs are predefined, and LDR indices are explicitly signaled by LDR syntax elements in the bitstream or implicitly derived from the bitstream. In any one of the exemplary implementations above, each group of LDRs is predefined as having a sample value range of 2N , where N is a non-negative integer and represents the bit depth of each group of LDRs. In any one of the exemplary implementations above, the LDR index is explicitly signaled by a value of 7-N. In any one of the exemplary implementations above, the LDR index is explicitly signaled by the LDR syntax element as a high-level syntax in the sequence header, picture header, subpicture header, frame header, slice header, or tile header. In any one of the exemplary implementations above, the LDR index is explicitly signaled as one or more block-level syntax by the LDR syntax element. In any one of the exemplary implementations above, the LDR index is signaled in one or more SEI (supplemental enhancement information) messages, each SEI message containing additional data inserted into the bitstream to convey additional information. In any one of the exemplary implementations above, LDR signaling indicating that an LDR is applied or an LDR applied to a block depends on the value of at least another syntax element within the bitstream. In any of the exemplary implementations above, LDR is applied only when the bitstream is intended for at least machine vision, as indicated by other syntax elements, or LDR signaling exists within the bitstream. In any of the exemplary implementations above, LDR is applied only when the block's quantization parameters are greater than a predefined quantization parameter threshold, or LDR signaling exists within the bitstream. In any of the exemplary implementations above, LDR is applied only when the picture resolution associated with the block is greater than or less than a predefined resolution value, or LDR signaling exists within the bitstream. In any of the exemplary implementations above, LDR is applied only when the frame rate associated with the block is greater than or less than a predefined frame rate value, or LDR signaling exists within the bitstream. In any one of the exemplary implementations above, LDRs for different color components of the block are signaled individually in the bitstream. In any of the exemplary implementations above, LDR is applied and signaled only to the block's luma component. In any one of the exemplary implementations above, the LDR selected to encode the block is implicitly derived based on the coded information of the block. Aspects of the present disclosure also provide an encoding method corresponding to the above decoding method. Aspects of the present disclosure also provide an electronic device or apparatus comprising a circuit or processor configured to perf