US-20260129202-A1 - METHODS OF CODING IMAGES/VIDEOS WITH ALPHA CHANNELS

US20260129202A1US 20260129202 A1US20260129202 A1US 20260129202A1US-20260129202-A1

Abstract

Example implementations include a method, apparatus and computer-readable medium of video coding, comprising determining, for a conversion between a video comprising a plurality of pictures and a bitstream of the video, first layer information which is utilized in a first process performed on a first layer of each picture. The implementations further include determining, second layer information which is utilized in a second process performed on a second layer of each picture. Additionally, the implementations further include performing the conversion for the second layer based on the first layer information and the second layer information.

Inventors

Weijia Zhu
Jizheng Xu
Li Zhang
Yue Wang

Assignees

LEMON INC.

Dates

Publication Date: 20260507
Application Date: 20251229

Claims (20)

1 . A method of video processing, comprising: determining, for a conversion between a video comprising a plurality of pictures and a bitstream of the video, first layer information which is utilized in a first process performed on a first layer of each picture; determining, second layer information which is utilized in a second process performed on a second layer of each picture; and performing the conversion for the second layer based on the first layer information and the second layer information, wherein transform units used to encode a prediction residual are identical with coding units for performance of the second process on the second layer.
2 . The method of claim 1 , wherein the first layer is a base layer corresponding to a color channel of the plurality of pictures, and the second layer is an alpha layer corresponding to a degree of transparency of the plurality of pictures; or the first layer is an alpha layer corresponding to a degree of transparency of the plurality of pictures, and the second layer is a base layer corresponding to a color channel of the plurality of pictures.
3 . The method of claim 1 , wherein the first layer information includes first block information of a first block in the first layer.
4 . The method of claim 3 , further comprising determining a context modeling for context-based adaptive binary arithmetic coding (CABAC) based on the first block information, wherein the context modeling based on the first block information is used for coding a second block in the second layer.
5 . The method of claim 3 , wherein second block information of a second block in the second layer is inherited from the first block information and the second block information is excluded in the bitstream.
6 . The method of claim 3 , wherein the first block information is used as a predictor for coding second block information of a second block in the second layer, or wherein the first block information is used for coding a second block in the second layer, and wherein the first block has a same top-left position and a same size with those of the second block.
7 . The method of claim 1 , further comprising determining prediction information based on a portion of the first layer information associated with a luma component of the first layer; and wherein the second layer information is determined based on the prediction information.
8 . The method of claim 1 , further comprising: performing a bit depth alignment on a plurality of samples of the first layer to determine bit aligned sample information as the first layer information; and determining prediction information based on a portion of the first layer information associated with a luma component of the first layer; and wherein the second layer information is determined based on the prediction information.
9 . The method of claim 1 , wherein the first layer information includes at least one of the following: intra-prediction mode information, motion information, a motion candidate index, or partition information for block structures of the first process and the second process.
10 . The method of claim 1 , further comprising: a second block in the second layer is reconstructed based on samples of at least a first block in the first layer.
11 . The method of claim 10 , wherein the first block has a same top-left position and a same size with those of the second block or neighboring blocks around the first block.
12 . The method of claim 10 , wherein the second block is reconstructed by performing a bitwise operation on the first block.
13 . The method of claim 12 , wherein the bitwise operation is denoted by C=R*a+b; where C is a sample of the second block, and R is a sample of the first block, a and b are constant, or wherein the bitwise operation is denoted by C=(R<<a)+b or by C=(R>>a)+b; where C is a sample of the second block, and R is a sample of the first block, a and b are constant.
14 . The method of claim 10 , wherein the first block is denoted by the samples before performing a loop filtering process or by the samples after performing a loop filtering process.
15 . The method of claim 14 , wherein the loop filtering process includes at least one of sample adaptive offset (SAO), adaptive loop filter (ALF) or deblocking filters.
16 . The method of claim 1 , wherein the conversion includes encoding the video into the bitstream, or wherein the conversion includes decoding the video from the bitstream.
17 . The method of claim 1 , wherein the bitstream comprises a current block in the second layer of a current picture that is predicted from one or more reference blocks in the first layer.
18 . The method of claim 17 , wherein at least one of the one or more reference blocks is located in the current picture; or at least one of the one or more reference blocks is located in at least one picture different from the current picture.
19 . A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining, for a conversion between a video comprising a plurality of pictures and a bitstream of the video, first layer information which is utilized in a first process performed on a first layer of each picture; determining, second layer information which is utilized in a second process performed on a second layer of each picture; and generating a bitstream of the video from the video comprises the second layer based on the first layer information and the second layer information, wherein the first layer information and the second layer information is utilized for the second layer.
20 . A non-transitory computer-readable storage medium storing instructions that cause a processor to: determine, for a conversion between a video comprising a plurality of pictures and a bitstream of the video, first layer information which is utilized in a first process performed on a first layer of each picture; determine, second layer information which is utilized in a second process performed on a second layer of each picture; and perform the conversion for the second layer based on the first layer information and the second layer information.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application is a continuation of U.S. application Ser. No. 17/187,670, filed on Feb. 26, 2021, which is related to U.S. application Ser. No. 17/187,667, filed on Feb. 26, 2021 and U.S. application Ser. No. 17/187,674, issued as U.S. Ser. No. 12/058,310B2 on Aug. 6, 2024, which are hereby incorporated by reference in their entireties. BACKGROUND The present disclosure relates generally to video coding, and more particularly, to video encoding and decoding of an alpha layer. SUMMARY The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later. An example implementation includes a method of video processing, comprising performing a conversion between a video comprising a plurality of pictures and a bitstream of the video, wherein each picture comprises an alpha layer and at least one base layer, wherein the bitstream comprises first layer information which is utilized in a first process performed on the at least one base layer and second layer information which is utilized in a second process performed on the alpha layer. Another example implementation includes an apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform a conversion between a video comprising a plurality of pictures and a bitstream of the video, wherein each picture comprises an alpha layer and at least one base layer, wherein the bitstream comprises first layer information which is utilized in a first process performed on the at least one base layer and second layer information which is utilized in a second process performed on the alpha layer. Another example implementation includes a non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: generating a bitstream of the video from the video comprising a plurality of picture, wherein each picture comprises an alpha layer and at least one base layer, wherein the bitstream comprises first layer information which is utilized in a first process performed on the at least one base layer and second layer information which is utilized in a second process performed on the alpha layer. Another example implementation includes a non-transitory computer-readable medium storing instructions that cause a processor to perform a conversion between a video comprising a plurality of pictures and a bitstream of the video, wherein each picture comprises an alpha layer and at least one base layer, wherein the bitstream comprises first layer information which is utilized in a first process performed on the at least one base layer and second layer information which is utilized in a second process performed on the alpha layer. An example implementation includes a method of video processing, comprising determining, for a conversion between a video comprising a plurality of pictures and a bitstream of the video, first layer information which is utilized in a first process performed on a first layer of each picture; and determining, second layer information which is utilized in a second process performed on a second layer of each picture. Additionally, the method further includes performing the conversion for the second layer based on the first layer information and the second layer information. Another example implementation includes an apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to determine, for a conversion between a video comprising a plurality of pictures and a bitstream of the video, first layer information which is utilized in a first process performed on a first layer of each picture; determine, second layer information which is utilized in a second process performed on a second layer of each picture; and perform the conversion for the second layer based on the first layer information and the second layer information; and perform the conversion for the second layer based on the first layer information and the second layer information. Another example implementation includes a non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining, for a conversion between a video comprising a plurality of pictures and