Adjustments to encoding and decoding when switching color spaces

Patent metadata

Field	Value
Publication number	US-2017318301-A1
Application number	US-201415517931-A
Country	US
Kind code	A1
Filing date	Oct 8, 2014
Priority date	Oct 8, 2014
Publication date	Nov 2, 2017
Grant date	—

Abstract

Innovations in encoding or decoding when switching color spaces are presented. For example, some of the innovations relate to signaling of control information for adaptive color space transformation (“ACT”). Other innovations relate to ACT operations. These innovations can improve coding efficiency when switching between color spaces during encoding and decoding.

First claim

1 . (canceled)

2 . In a computing system with an image decoder or video decoder, a method comprising:
receiving encoded data as part of a bitstream; and decoding the encoded data to reconstruct a unit of an image or video, wherein the decoding includes:
evaluating a condition for a coding unit (“CU”), wherein the CU has multiple prediction units (“PUs”), and wherein the evaluating the condition includes checking whether chroma mode for each of the multiple PUs is direct mode; and
conditionally parsing a syntax element that indicates color space for the CU, including parsing the syntax element if the condition is satisfied but otherwise skipping the parsing of the syntax element.

3 . The method of claim 2 , wherein coding mode of the CU is intra-picture prediction, and wherein the direct mode indicates that a prediction direction for a primary color component is also used for secondary color components.

4 . The method of claim 2 , wherein the syntax element is a flag value that indicates a selection between first color space and second color space for the CU, and wherein selection of the first color space is implied for the CU if the syntax element is not present in the bitstream.

5 . The method of claim 2 , wherein the evaluating the condition further includes checking whether the CU has residual data and checking whether adaptive color space transformation (“ACT”) is enabled.

6 . The method of claim 5 , wherein the evaluating the condition further includes checking whether coding mode of the CU is inter-picture prediction or intra-picture block copy prediction.

7 . The method of claim 6 , wherein:
the condition is satisfied if (a) the CU has residual data, (b) ACT is enabled, and (c) the coding mode of the CU is inter-picture prediction, the coding mode of the CU is intra-picture block copy prediction, or the chroma mode for each of the multiple PUs is direct mode; and otherwise, the condition is not satisfied.

8 .- 50 . (canceled)

51 . The method of claim 4 , wherein the first color space is an RGB-type color space, and wherein the second color space is a YCoCg-type color space.

52 . A computing system comprising one or more processing units, memory, and storage, wherein the memory and/or storage have encoded therein computer-executable instructions for causing the computing system, when programmed thereby, to perform operations comprising:
encoding a unit of an image or video to produce encoded data, wherein the encoding includes:
evaluating a condition for a coding unit (“CU”), wherein the CU has multiple prediction units (“PUs”), and wherein the evaluating the condition includes checking whether chroma mode for each of the multiple PUs is direct mode; and
conditionally signaling a syntax element that indicates color space for the CU, including signaling the syntax element if the condition is satisfied but otherwise skipping the signaling of the syntax element; and
outputting the encoded data as part of a bitstream.

53 . The computing system of claim 52 , wherein coding mode of the CU is intra-picture prediction, and wherein the direct mode indicates that a prediction direction for a primary color component is also used for secondary color components.

54 . The computing system of claim 52 , wherein the syntax element is a flag value that indicates a selection between first color space and second color space for the CU, and wherein selection of the first color space is implied for the CU if the syntax element is not present in the bitstream.

55 . The computing system of claim 54 , wherein the first color space is an RGB-type color space, and wherein the second color space is a YCoCg-type color space.

56 . The computing system of claim 52 , wherein the evaluating the condition further includes checking whether the CU has residual data and checking whether adaptive color space transformation (“ACT”) is enabled.

57 . The computing system of claim 56 , wherein the evaluating the condition further includes checking whether coding mode of the CU is inter-picture prediction or intra-picture block copy prediction.

58 . The computing system of claim 57 , wherein:
the condition is satisfied if (a) the CU has residual data, (b) ACT is enabled, and (c) the coding mode of the CU is inter-picture prediction, the coding mode of the CU is intra-picture block copy prediction, or the chroma mode for each of the multiple PUs is direct mode; and otherwise, the condition is not satisfied.

59 . One or more computer-readable media having stored therein computer-executable instructions for causing a computing system, when programmed thereby, to perform operations comprising:
receiving encoded data as part of a bitstream; and decoding the encoded data to reconstruct a unit of an image or video, wherein the decoding includes:
evaluating a condition for a coding unit (“CU”), wherein the CU has multiple prediction units (“PUs”), and wherein the evaluating the condition includes checking whether chroma mode for each of the multiple PUs is direct mode; and
conditionally parsing a syntax element that indicates color space for the CU, including parsing the syntax element if the condition is satisfied but otherwise skipping the parsing of the syntax element.

60 . The one or more computer-readable media of claim 59 , wherein coding mode of the CU is intra-picture prediction, and wherein the direct mode indicates that a prediction direction for a primary color component is also used for secondary color components.

61 . The one or more computer-readable media of claim 59 , wherein the syntax element is a flag value that indicates a selection between first color space and second color space for the CU, and wherein selection of the first color space is implied for the CU if the syntax element is not present in the bitstream.

62 . The one or more computer-readable media of claim 59 , wherein the evaluating the condition further includes checking whether the CU has residual data and checking whether adaptive color space transformation (“ACT”) is enabled.

63 . The one or more computer-readable media of claim 62 , wherein the evaluating the condition further includes checking whether coding mode of the CU is inter-picture prediction or intra-picture block copy prediction.

64 . The one or more computer-readable media of claim 63 , wherein:
the condition is satisfied if (a) the CU has residual data, (b) ACT is enabled, and (c) the coding mode of the CU is inter-picture prediction, the coding mode of the CU is intra-picture block copy prediction, or the chroma mode for each of the multiple PUs is direct mode; and otherwise, the condition is not satisfied.

Assignees

• Li Bin
• Xu Jizheng
• Sullivan Gary J
• Microsoft Technology Licensing Llc

Inventors

• Li Bin
• Xu Jizheng
• Sullivan Gary J

Classifications

• H04N1/644

  using a reduced set of representative colours, e.g. each representing a particular range in a colour space · CPC title

• H04N19/186 Primary

  the unit being a colour or a chrominance component · CPC title

• H04N19/184

  the unit being bits, e.g. of the compressed video stream · CPC title

• H04N19/126

  Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers · CPC title

• H04N19/70

  characterised by syntax aspects related to video coding, e.g. related to compression standards · CPC title