WO2016197392A1 - Improvements for non-local index prediction - Google Patents

Improvements for non-local index prediction Download PDF

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WO2016197392A1
WO2016197392A1 PCT/CN2015/081374 CN2015081374W WO2016197392A1 WO 2016197392 A1 WO2016197392 A1 WO 2016197392A1 CN 2015081374 W CN2015081374 W CN 2015081374W WO 2016197392 A1 WO2016197392 A1 WO 2016197392A1
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coded
local index
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Weijia Zhu
Kai Zhang
Xianguo Zhang
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MediaTek Singapore Pte Ltd
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Priority to PCT/CN2015/081374 priority Critical patent/WO2016197392A1/en
Priority to US15/556,389 priority patent/US10148981B2/en
Priority to CN201680010328.9A priority patent/CN107409227B/en
Priority to EP16767720.2A priority patent/EP3266212A4/en
Priority to KR1020177026536A priority patent/KR102051197B1/en
Priority to PCT/CN2016/076726 priority patent/WO2016150343A1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
    • H04N19/93—Run-length coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/11—Selection of coding mode or of prediction mode among a plurality of spatial predictive coding modes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/182—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a pixel
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/186—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a colour or a chrominance component

Definitions

  • Fig. 4 is a diagram illustrating non-local index prediction method.
  • the reconstructed indices with the coded run length can be obtained by copying from the indices in the reference block.
  • each pixel can choose copy-left method, copy-above method, and non-local index prediction method.
  • Several flags can be coded to represent the chosen result.
  • a decoder can infer the chosen result for the current pixel implicitly.
  • One or more bits are coded for each run to indicate whether the coded run is the last run of the current block.
  • index redundancy removal cannot be performed for those samples. To solve this problem, coding one or more additional refinement bits is performed and index redundancy removal can be always performed for all samples.
  • the parsed out index is equal to MAX_INDEX-1
  • one additional refinement bit should be parsed. If the refinement bit is equal to 1, the reconstructed index is MAX_INDEX-1. Otherwise, the reconstructed index is MAX_INDEX-2.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

Several improvements for non-local index prediction methods are proposed. By utilizing these improvements, the performance of non-local index prediction method is improved.

Description

IMPROVEMENTS FOR NON-LOCAL INDEX PREDICTION TECHNICAL FIELD
The invention relates generally to video/image processing. In particular, the presented invention relates to palette coding.
BACKGROUND
In the current HEVC screen content coding extensions draft specification [1] , palette mode was adopted to efficiently compress the texts and graphics in screen contents. The basic idea behind a palette mode is that the samples in the CU are represented by a small set of representative color values. This set is referred to as the palette. It is also possible to indicate a sample that is outside the palette by signaling an escape symbol followed by (possibly quantized) component values. This is illustrated in Fig. 1.
Each sample in the block is assigned the index of the nearest (in SAD) palette entry. The palette indices are coded using two main modes: 'INDEX' and 'COPY_ABOVE'. The escape symbol is also signaled as an 'INDEX' mode. It is assigned an index equal to the maximum palette size. The mode is signaled using a flag except for the top row or when the previous mode was 'COPY_ABOVE'. In the 'COPY_ABOVE' mode, the palette index of the sample in the row above is copied. In the 'INDEX' mode, the palette index is explicitly signaled. For both 'INDEX' and 'COPY_ABOVE' modes, a run value is signaled which specifies the number of subsequent samples that are also coded using the same mode. When escape symbol is part of the run in 'INDEX' or 'COPY_ABOVE' mode, the escape component values are signaled for each escape symbol. The coding of palette indices is illustrated in Fig. 2.
The ‘COPY_ABOVE’ mode in PLT mode only takes the palette index of the sample in the row above into account. There are a large number of non-local duplicated contents in screen pictures as depicted in Fig. 3. Thus a lot of non-local repeated indices can be observed in the whole picture.
The ‘COPY_ABOVE’ mode cannot deal with non-local duplicated indexes efficiently.
SUMMARY
In light of the previously described problems, non-local index prediction methods are proposed.
Other aspects and features of the invention will become apparent to those with ordinary skill in the art upon review of the following descriptions of specific embodiments.
BRIEF DESCRIPTION OF DRAWINGS
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
Fig. 1 is an example of a block coded in palette mode；
Fig. 2 is a diagram illustrating the coding manner of palette indices；
Fig. 3 is a diagram illustrating the non-local repeated patterns in screen contents；
Fig. 4 is a diagram illustrating non-local index prediction method.
DETAILED DESCRIPTION
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
Several improved non-local index prediction (NIP) methods are proposed. In the original NIP methods, non-local index map can be used to predict the index map of the current block, as shown in Fig 4.
In one embodiment, the reconstructed indices with the coded run length can be obtained by copying from the indices in the reference block.
In another embodiment, the reconstructed samples with the coded run length can be obtained by copying from the samples in the reference block.
In still another embodiment, each pixel can choose copy-left method, copy-above method, and non-local index prediction method. Several flags can be coded to represent the chosen result. A decoder can infer the chosen result for the current pixel implicitly.
In still another embodiment, the flags used to represent the chosen results can be CABAC coded or context coded. The flags of neighboring pixels also can be used as contexts for the current flag.
In still another embodiment, the current pixel cannot choose the non-local index prediction method if the previous one pixel selects the non-local index prediction method.
In still another embodiment, the current pixel cannot choose the non-local index prediction method if the previous one pixel selects the non-local index prediction method.
One or more bits are coded for each run to indicate whether the coded run is the last run of the current block.
Since some samples are unavailable in the parsing process, index redundancy removal cannot be performed for those samples. To solve this problem, coding one or more additional refinement bits is performed and index redundancy removal can be always performed for all samples.
In one embodiment, if the parsed out index is equal to MAX_INDEX-1, one additional refinement bit should be parsed. If the refinement bit is equal to 1, the reconstructed index is MAX_INDEX-1. Otherwise, the reconstructed index is MAX_INDEX-2.
Since some samples are unavailable in the parsing process, index redundancy removal cannot be performed for those samples. To solve this problem, coding all run type flags before coding all indices is proposed. And index redundancy removal is not performed for NIP samples.
An exemplary syntax structure is described as below.
7.3.8.8 Palette syntax
Figure PCTCN2015081374-appb-000001
Figure PCTCN2015081374-appb-000002
Figure PCTCN2015081374-appb-000003
Figure PCTCN2015081374-appb-000004
Figure PCTCN2015081374-appb-000005
7.4.9.6 Palette mode semantics
copy_inter_flag equal to 1 specifies that the current coding unit is coded by inter palette mode. palette_mode_flag equal to 0 specifies that the current coding unit is not coded by inter palette mode.
When copy_inter_flag  is not present, it is inferred to be equal to 0.
last_copy_inter_run_type_flag equal to 1 specifies that the last one run type is COPY_INTER mode.
A variable LastRunType is set equal to  last_copy_inter_run_type_flag？ COPY_INTER_MODE : (last_palette_run_type_flag  ？ COPY_ABOVE_MODE : COPY_INDEX_MODE )
inter_run_type_flag equal to 1 specifies that the current palette index is equal to the palette index at the same location inside the index map of the block indicated by the decoded block vector.
A variable RunType [xC] [yC] is set equal to inter_run_type_flag [xC] [yC] ？ COPY_INTER_MODE : (last_palette_run_type_flag [xC] [yC] ？ COPY_ABOVE_MODE : COPY_INDEX_MODE )
palette_index_refinement_bits equal to 1 specifies that the current palette index is equal to CurrentPaletteSize minus 1
last_run_flag equal to 1 specifies that the current run is the last run in the current block.
The variable InterIndexMap [xC] [yC] specifes a palette index in the refence index map, which is an index to the array represented by CurrentPaletteEntries. The reference index map refers to the index map of the block indicated by the decoded block vector. The array indices xC, yC specify the location (xC , yC) of the sample relative to the top-left luma sample of the picture. The value of InterIndexMap [xC] [yC] shall be in the range of 0 to MaxPaletteIndex, inclusive.
In another embodiment, the run type for the current pixel should not be COPY_INTER if the run type for the previous pixel is COPY_INTER.
In one embodiment, part of the syntax structure should be
Figure PCTCN2015081374-appb-000006
The methods described above can be used in a video encoder as well as in a video decoder. Embodiments of disparity vector derivation methods according to the present invention as described above may be implemented in various hardware, software codes, or a combination of both. For example, an embodiment of the present invention can be a circuit integrated into a video compression chip or program codes integrated into video compression software to perform the processing described herein. An embodiment of the present invention may also be program codes to be executed on a Digital Signal Processor (DSP) to perform the processing described herein. The invention may also involve a number of functions to be performed by a computer processor, a digital signal processor, a microprocessor, or field programmable gate array (FPGA) . These processors can be configured to perform particular tasks according to the invention, by executing machine-readable software code or firmware code that defines the particular methods embodied by the invention. The software code or firmware codes may be developed in different programming languages and different format or style. The software code may also be compiled for different target platform. However, different code formats, styles and languages of software codes and other means of configuring code to perform the tasks in accordance with the invention will not depart from the spirit and scope of the invention.
The methods described above can be used in a video encoder as well as in a video decoder. Embodiments of disparity vector derivation methods according to the present invention as described above may be implemented in various hardware,  software codes, or a combination of both. For example, an embodiment of the present invention can be a circuit integrated into a video compression chip or program codes integrated into video compression software to perform the processing described herein. An embodiment of the present invention may also be program codes to be executed on a Digital Signal Processor (DSP) to perform the processing described herein. The invention may also involve a number of functions to be performed by a computer processor, a digital signal processor, a microprocessor, or field programmable gate array (FPGA) . These processors can be configured to perform particular tasks according to the invention, by executing machine-readable software code or firmware code that defines the particular methods embodied by the invention. The software code or firmware codes may be developed in different programming languages and different format or style. The software code may also be compiled for different target platform. However, different code formats, styles and languages of software codes and other means of configuring code to perform the tasks in accordance with the invention will not depart from the spirit and scope of the invention.
The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described examples are to be considered in all respects only as illustrative and not restrictive. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art) . Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims (10)

  1. A method of non-local index prediction, wherein a non-local index map is used to predict the index map of the current block.
  2. The method as claimed in claim 1, wherein the reconstructed indices with the coded run length are copied from the indices in the reference block.
  3. The method as claimed in claim 1, wherein the reconstructed samples with the coded run length are copied from the samples in the reference block.
  4. The method as claimed in claim 1, wherein each pixel can choose copy-left method, copy-above method, and non-local index prediction method； Several flags can be coded to represent the chosen result； A decoder can infer the chosen result for the current pixel implicitly.
  5. The method as claimed in claim 1, wherein the flags used to represent the chosen results can be CABAC coded or context coded； The flags of neighboring pixels also can be used as contexts for the current flag.
  6. The method as claimed in claim 1, wherein the current pixel cannot choose the non-local index prediction method if the previous one pixel selects the non-local index prediction method.
  7. The method as claimed in claim 1, wherein the current pixel cannot choose the non-local index prediction method if the previous one pixel selects the non-local index prediction method.
  8. The method as claimed in claim 1, wherein one or more bits are coded for each run to indicate whether the coded run is the last run of the current block.
  9. The method as claimed in claim 1, wherein the indices in the current index map are coded a different way to the case where non-local index prediction is not used when non-local index prediction is used for the current block.
  10. The method as claimed in claim 1, wherein if the parsed out index is equal to MAX_INDEX-1, one additional refinement bit should be parsed； If the refinement bit is equal to 1, the reconstructed index is MAX_INDEX-1； Otherwise, the reconstructed index is MAX_INDEX-2.
PCT/CN2015/081374 2015-03-20 2015-06-12 Improvements for non-local index prediction Ceased WO2016197392A1 (en)

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Application Number Priority Date Filing Date Title
PCT/CN2015/081374 WO2016197392A1 (en) 2015-06-12 2015-06-12 Improvements for non-local index prediction
US15/556,389 US10148981B2 (en) 2015-03-20 2016-03-18 Methods of palette coding with inter-prediction in video coding
CN201680010328.9A CN107409227B (en) 2015-03-20 2016-03-18 Video coding and decoding method and device
EP16767720.2A EP3266212A4 (en) 2015-03-20 2016-03-18 Methods of palette coding with inter-prediction in video coding
KR1020177026536A KR102051197B1 (en) 2015-03-20 2016-03-18 Palette Coding Method with Inter Prediction in Video Coding
PCT/CN2016/076726 WO2016150343A1 (en) 2015-03-20 2016-03-18 Methods of palette coding with inter-prediction in video coding

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015077720A1 (en) * 2013-11-22 2015-05-28 Futurewei Technologies, Inc. Advanced screen content coding solution

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015077720A1 (en) * 2013-11-22 2015-05-28 Futurewei Technologies, Inc. Advanced screen content coding solution

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
LIWEI, GUO ET AL.: "Non-RCE3: Modified Palette Mode for Screen Content Coding", JOINT COLLABORATIVE TEAM ON VIDEO CODING (JCT-VC)OF ITU-T SG 16 WP 3 AND ISO/IEC JTC 1/SC 29/WG 11 14TH MEETING JCTVC-N0249, 2 August 2013 (2013-08-02), Vienna, AT ., pages 1, XP030114767 *
LIWEI, GUO ET AL.: "RCE3: Results of Test 3.1 on Palette Mode for Screen Content Coding", JOINT COLLABORATIVE TENM ON VIDEO CODING (JCT-VC)OF ITU-T SG 16 WP 3 AND ISO/IEC JTC 1/SC 29/WOG 77 14TH MEETING JCTVC-N0247, 2 August 2013 (2013-08-02), Vienna, AT ., XP030114764 *

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