WO2016054774A1 - A method for the co-existence of color-space transform and cross-component prediction - Google Patents

A method for the co-existence of color-space transform and cross-component prediction Download PDF

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WO2016054774A1
WO2016054774A1 PCT/CN2014/088140 CN2014088140W WO2016054774A1 WO 2016054774 A1 WO2016054774 A1 WO 2016054774A1 CN 2014088140 W CN2014088140 W CN 2014088140W WO 2016054774 A1 WO2016054774 A1 WO 2016054774A1
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current
ccp
cst
utilized
tus
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PCT/CN2014/088140
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Xianguo Zhang
Kai Zhang
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Mediatek Singapore Pte. Ltd.
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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
    • H04N19/10—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
    • 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
    • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
    • 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
    • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
    • 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
    • H04N19/17—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 an image region, e.g. an object
    • H04N19/176—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 an image region, e.g. an object the region being a block, e.g. a macroblock

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  • the invention relates generally to video/image coding/processing. Particularly, it is related to the co-existence of color-space transform (CST) and cross-component prediction (CCP) .
  • CST color-space transform
  • CCP cross-component prediction
  • both CST and CCP are proposed to reduce the redundancy among different color components.
  • CCP firstly locates the collocated each luma transform block’s (TB’s) prediction residuals. These luma TB residuals are the reconstructed data from entropy decoding and inverse transforming. Then the luma TB residuals are utilized to predict the two groups of chroma TB residuals. And then, all TB residuals are compensated by inter or intra prediction data. At last, all TB data are decoded and construct the decoded CU data.
  • TB luma transform block
  • an alpha parameter is transmitted in transform unit of the video stream and the luma TB residual multiplied by the alpha parameter and right shifted by 3 bits are utilized as the predicted residuals for the current component TB residuals.
  • the decoding flow for the color-space transform is depicted in Fig. 2.
  • the added module namely inverse color transform, is highlighted.
  • the inverse color transform is invoked to convert the residual domain back to the original domain.
  • a flag is signaled to indicate the usage of color-space transform in a CU.
  • intra BC and inter modes such a flag is signaled only when there is at least one non-zero coefficient in the current CU.
  • intra modes such a flag is signaled only when the chroma mode of the first PU (i. e., top-left PU within one CU) is coded with DM mode.
  • the forward and the inverse color-space transforms for lossy coding use the YCoCg transform matrices, which are defined as follows:
  • Fig. 1 is a diagram illustrating the decoding flowchart of CCP
  • Fig. 2 is a diagram illustrating the decoding flowchart of CST
  • Fig. 3 is a diagram illustrating the decoding flowchart of the suggested decoding process of co-existing CCP and CST.
  • CST and CCP are never utilized together.
  • CCP cannot be utilized for any TU corresponding to the current CU.
  • CCP cannot be utilized for any TU larger than m ⁇ m corresponding to the current CU.
  • m is equal to 4 as shown in Fig. 3.
  • CCP cannot be utilized for any TU when the current CU is encoded by one subset of all the inter, intra or intra block copy modes. For example, if CST is utilized or the current inter CU, CCP is not utilized.
  • CST if CCP is utilized the current CU, CST cannot be utilized if CCP is utilized for more than x percentage pixels. For example, if CCP is utilized for more 10%pixels of the current CU, CST is not utilized.
  • CST cannot be utilized when the current CU is encoded by one subset of all the intra, inter or intra block copy modes. For example, if CCP is utilized for the current inter CU, CST is not utilized.
  • CST cannot be utilized when the current CU is smaller than m ⁇ m. For example, if CCP is utilized current 8x8 CU (m is set 16) , CST is not utilized.
  • any methods combining the some of the above methods can be included.
  • 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.
  • DSP Digital Signal Processor
  • 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) .
  • 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.
  • 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.

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

Abstract

Methods are proposed to constrain the co-existence of CCP and CST.

Description

A METHOD FOR THE CO-EXISTENCE OF COLOR-SPACE TRANSFORM AND CROSS-COMPONENT PREDICTION TECHNICAL FIELD
The invention relates generally to video/image coding/processing. Particularly， it is related to the co-existence of color-space transform (CST) and cross-component prediction (CCP) .
BACKGROUND
For HEVC-SCC， both CST and CCP are proposed to reduce the redundancy among different color components.
The basic decoding process the CCP in the current HEVC-SCC is illustrated in Fig. 1. CCP firstly locates the collocated each luma transform block’s (TB’s) prediction residuals. These luma TB residuals are the reconstructed data from entropy decoding and inverse transforming. Then the luma TB residuals are utilized to predict the two groups of chroma TB residuals. And then， all TB residuals are compensated by inter or intra prediction data. At last， all TB data are decoded and construct the decoded CU data.
During each procedure of utilizing 1 st component TB residuals to predict the current second or third TB residuals， an alpha parameter is transmitted in transform unit of the video stream and the luma TB residual multiplied by the alpha parameter and right shifted by 3 bits are utilized as the predicted residuals for the current component TB residuals. In the current IRP design， alpha values among-8， -4， -2， -1， 0， 1， 2， 4 and 8.
Whereas for color-space transform， or namely adaptive color transform [1] [2] ， the decoding flow for the color-space transform is depicted in Fig. 2. The added module， namely inverse color transform， is highlighted. When one block is coded with color transform enabled， after the conventional inverse DCT/DST transform and CCP， the inverse color transform is invoked to convert the residual domain back to the original domain. A flag is signaled to indicate the usage of color-space transform in a CU. For intra BC and inter modes， such a flag is signaled only  when there is at least one non-zero coefficient in the current CU. For intra modes， such a flag is signaled only when the chroma mode of the first PU (i. e.， top-left PU within one CU) is coded with DM mode.
Two different color-space transforms are applied depending on whether the CU is coded losslessly or in a lossy manner. The forward and the inverse color-space transforms for lossy coding use the YCoCg transform matrices， which are defined as follows：
Forward： 
Figure PCTCN2014088140-appb-000001
Inverse： 
Figure PCTCN2014088140-appb-000002
It is obvious that there must be some performance overlap between CCP and CST， since they can both work by reducing the power of the residuals in the second and third color components. In such case， the co-existence of CCP and CST enlarges the decoding time. Therefore， this invention is proposed to constrain the co-existence of CCP and CST. .
SUMMARY
In light of the previously described problems， methods are proposed to signal the palette table correctly and efficiently.
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 a diagram illustrating the decoding flowchart of CCP；
Fig. 2 is a diagram illustrating the decoding flowchart of CST；
Fig. 3 is a diagram illustrating the decoding flowchart of the suggested decoding process of co-existing CCP and CST.
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.
In order to reduce the complexity of doing CCP and CST together in the decoding process， we propose several simplification methods to constrain the co-exsiting of CCP and CST.
In one embodiment， CST and CCP are never utilized together.
In second embodiment， if CST is utilized for the current CU， CCP cannot be utilized for any TU corresponding to the current CU.
In another embodiment， if CST is utilized for the current CU， CCP cannot be utilized for any TU larger than m×m corresponding to the current CU. For example， m is equal to 4 as shown in Fig. 3.
In still another embodiment， if CST is utilized for the current CU， CCP cannot be utilized for any TU when the current CU is encoded by one subset of all the inter， intra or intra block copy modes. For example， if CST is utilized or the current inter CU， CCP is not utilized.
In still another embodiment， if CCP is utilized the current CU， CST cannot be utilized if CCP is utilized for more than x percentage pixels. For example， if CCP is utilized for more 10％pixels of the current CU， CST is not utilized.
In still another embodiment， if CCP is utilized for the current CU， CST cannot be utilized when the current CU is encoded by one subset of all the intra， inter or intra block copy modes. For example， if CCP is utilized for the current inter CU， CST is not utilized.
In still another embodiment， if CCP is utilized for the current CU， CST cannot be utilized when the current CU is smaller than m×m. For example， if CCP is utilized current 8x8 CU (m is set 16) ， CST is not utilized.
In still other embodiments， any methods combining the some of the above methods can be included.
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.
References：
[1] L. Zhang， J. Chen， J. Sole， M. Karczewicz， “AhG8： In-loop color-space transform， ” JCTVC-Q0112， Apr. 2014.
[2] L. Zhang， J. Chen， J. Sole， M. Karczewicz， X. Xiu， Y. He， Y. Ye， “SCCE5 Test 3.2.1： In-loop color-space transform， ” JCTVC-R0147， Jul. 2014.
[3] R. Joshi， J. Xu， “HEVC Screen Content Coding Draft Text 1” ， JCTVC-R1005， Jul. 2014.

Claims (22)

  1. A method guarateeing that CCP and CST cannot be co-existed in some kinds of CU or TUs is applied.
  2. The method as claimed in claim 1, wherein if CST is utilized for one CU, CCP cannot be applied to some kinds of TUs corresponding to this CU.
  3. The method as claimed in claim 1, wherein if CCP is permitted for one CU, CST cannot be applied to this CU at some kinds of conditions.
  4. The method as claimed in claim 2, wherein if CST is utilized for the current CU, CCP cannot be applied to the inside TUs if the current CU size is smaller than m×m. For example, m is equal to 16.
  5. The method as claimed in claim 2, wherein if CST is utilized for the current CU, CCP cannot be applied to the inside TUs which are smaller than m×m when the current CU is predicted by modes in one subset of all the intra, inter or intra block copy modes. When m is set larger than the largest TU size, it means no limitation on the TU size.
  6. The method as claimed in claim 5, wherein if CST is utilized for the current CU, CCP cannot be applied to the inside TUs.
  7. The method as claimed in claim 5, wherein if CST is utilized for the current CU, CCP cannot be applied to the inside TUs which are larger than m×m no matter what mode the current CU is coded by. When m is set larger than the largest TU size, it means no limitation on the TU size.
  8. The method as claimed in claim 5, wherein if CST is utilized for the current CU, CCP cannot be applied to the inside TUs which are larger than m×m when the current CU is coded by inter modes. When m is set larger than the largest TU size, it means no limitation on the TU size.
  9. The method as claimed in claim 5, wherein if CST is utilized for the current CU, CCP cannot be applied to the inside TUs which are larger than m×m when the current CU is coded by intra block copy modes. When m is set larger than the largest TU size, it means no limitation on the TU size.
  10. The method as claimed in claim 5, wherein if CST is utilized for the current CU, CCP cannot be applied to the inside TUs which are larger than m×m when the current CU is coded by intra modes. When m is set larger than the largest TU size, it means no limitation on the TU size.
  11. The method as claimed in claim 3, wherein if CCP is utilized for some TUs of the current CU, CST cannot be applied to the current CU when the current CU is predicted by modes in one subset of all the intra, inter or intra block copy modes.
  12. The method as claimed in claim 11, if CCP is utilized for more than x percentage of the pixels (covered by the TUs utilized CCP) of the current CU, CST cannot be applied to the current CU when the current CU is predicted by modes in one subset of all the intra, inter or intra block copy modes.
  13. The method as claimed in claim 11, if CCP is utilized for more than x TUs of the current CU, CST cannot be applied to the current CU when the current CU is predicted by modes in one subset of all the intra, inter or intra block copy modes.
  14. The method as claimed in claim 11 to claim 13, wherein the related subset indentifies all the intra modes.
  15. The method as claimed in claim 11 to claim 13, wherein the related subset indentifies all the inter modes.
  16. The method as claimed in claim 11 to claim 13, wherein the related subset indentifies all the intra block copy modes.
  17. The method as claimed in claim 11, wherein if CCP is utilized for any TU of the current CU, CST cannot be applied.
  18. The method as claimed in claim 11, wherein if CCP is allowed for the current CU, CST cannot be applied.
  19. The method as claimed in claim 5, wherein if CST is applied to the current CU, CCP cannot be applied.
  20. The method as claimed in claim 5, wherein if CST is applied to the current CU, CCP can be only applied to its inside 4×4 TUs.
  21. The method as claimed in claim 5, wherein if CST is not applied to the current CU, CCP can be applied to all its inside TUs.
  22. The method as claimed in claim 5, wherein if CST is allowed to the current CU, CCP cannot be applied.
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