ADJUSTMENTS TO ENCODING AND DECODING WHEN SWITCHING COLOR SPACES

• US 20170318301A1
• Filed: 10/08/2014
• Published: 11/02/2017
• Est. Priority Date: 10/08/2014
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Li, Bin, Xu, Jizheng, Sullivan, Gary J.
• Granted Patent: US 10,687,069 B2
• Time in Patent Office: Days
• CPC Class Codes: H04N 1/644 using a reduced set of representative colours, e.g. each representing a particular range in a colour space
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

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.

Claims

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.

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.

8-50. -50. (canceled)

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.