WO2020140700A1 - 色度块的预测方法和装置 - Google Patents

色度块的预测方法和装置 Download PDF

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WO2020140700A1
WO2020140700A1 PCT/CN2019/124399 CN2019124399W WO2020140700A1 WO 2020140700 A1 WO2020140700 A1 WO 2020140700A1 CN 2019124399 W CN2019124399 W CN 2019124399W WO 2020140700 A1 WO2020140700 A1 WO 2020140700A1
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Prior art keywords
chroma
brightness
values
pixels
block
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PCT/CN2019/124399
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English (en)
French (fr)
Inventor
马祥
牟凡
赵寅
杨海涛
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华为技术有限公司
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Priority to MX2021008151A priority Critical patent/MX2021008151A/es
Priority to JP2021538946A priority patent/JP7239711B2/ja
Priority to AU2019419130A priority patent/AU2019419130A1/en
Priority to CN201980022524.1A priority patent/CN111919444B/zh
Priority to DK19907227.3T priority patent/DK3907995T3/da
Priority to EP19907227.3A priority patent/EP3907995B1/en
Priority to CA3125500A priority patent/CA3125500A1/en
Priority to KR1020217024140A priority patent/KR20210103573A/ko
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP23218442.4A priority patent/EP4362462A1/en
Priority to FIEP19907227.3T priority patent/FI3907995T3/fi
Priority to BR112021013163-9A priority patent/BR112021013163A2/pt
Publication of WO2020140700A1 publication Critical patent/WO2020140700A1/zh
Priority to US17/365,372 priority patent/US11943451B2/en
Priority to JP2023031553A priority patent/JP7492051B2/ja

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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
    • H04N19/134—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
    • H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame 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
    • H04N19/169—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
    • 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
    • H04N19/103—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
    • H04N19/169—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
    • 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
    • H04N19/42—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation
    • 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
    • H04N19/10—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
    • H04N19/132—Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
    • 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
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding

Definitions

  • the present application relates to the technical field of video encoding and decoding, in particular to a method and device for predicting chroma blocks.
  • the general coding process mainly includes intra prediction, inter prediction, transformation, quantization, entropy coding, and in-loop filtering.
  • CCLM Cross Component Linear Mode
  • CCP Cross-Component Predition
  • LM simply linear mode
  • the scaling factor and the offset factor do not need to be encoded and transmitted, but are derived using the edge pixels of the neighboring reconstructed blocks of the current chroma block and the luminance pixels at the corresponding positions of the edge pixels.
  • N is the number of edge pixels of adjacent reconstructed blocks
  • L(n) is the nth luma pixel
  • C(n) is the nth chroma pixel.
  • each chroma block using CCLM needs to determine the scaling factor and the offset factor.
  • the complexity is high, resulting in a low prediction efficiency of the chroma block.
  • the embodiments of the present application provide a method and a device for predicting chroma blocks.
  • the technical solution is as follows:
  • a method for predicting chroma blocks includes:
  • the chromaticity value of the chromaticity pixel at the preset position from the adjacent pixels of the chromaticity block. Based on the adjacent pixels of the luminance block corresponding to the chroma block, the luminance value of the luminance pixel corresponding to the chroma pixel at the preset position is acquired. The obtained brightness value is divided into a first brightness set and a second brightness set. The chromaticity values of the chromaticity pixels corresponding to the luminance pixels to which the luminance value in the first luminance set belongs to form a first chromaticity set, and the luminance pixels corresponding to the luminance The chromaticity values of the chromaticity pixels form a second chromaticity set.
  • the average value of determines the scaling factor in the linear model corresponding to the chroma block.
  • the scaling factor determine an offset factor in the linear model corresponding to the chroma block.
  • the prediction information of the chroma block is determined according to the scaling factor, the offset factor, and the luminance reconstruction information corresponding to the chroma block.
  • the chroma pixel at a preset position may be obtained from adjacent pixels of the chroma block Chroma value. Then, the brightness block corresponding to the chroma block may be determined, and based on the adjacent pixels of the brightness block, the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position may be obtained. The obtained brightness value is divided into a first brightness set and a second brightness set. According to the brightness value, the chromaticity value is automatically divided into a first chromaticity set and a second chromaticity set.
  • the scaling factor in the corresponding linear model uses the scaling factor to determine the offset factor in the linear model corresponding to the chroma block, and finally use the brightness reconstruction information, scaling factor and offset factor corresponding to the chroma block to obtain the prediction information of the chroma block, the brightness corresponding to the chroma block.
  • the reconstruction information includes the down-sampling information of the luminance reconstruction block corresponding to the chroma block.
  • the acquiring the chromaticity value of the chromaticity pixel at the preset position based on the adjacent pixels of the chromaticity block includes: acquiring indication information, and determining the corresponding Intra prediction mode, wherein the intra prediction mode includes at least one of a linear mode LM, an upper linear mode (LMA) and a left linear mode (LML), according to the chroma
  • the intra prediction mode corresponding to the block determines the preset position.
  • the indication information when encoding at the encoding end, may be encoded into the code stream, and then sent to the decoding end.
  • the decoding end may obtain indication information in the received code stream, and determine the intra prediction mode corresponding to the chroma block based on the indication information. Then, based on the intra prediction mode corresponding to the chroma block, the preset position is determined. In this way, the decoding end can determine the intra prediction mode used by the brightness block, and then determine the preset position based on the intra prediction mode.
  • the acquiring the chromaticity value of the chromaticity pixel at the preset position from adjacent pixels of the chromaticity block includes: according to a correspondence between the preset intra prediction mode and the preset position Relationship, and the intra prediction mode corresponding to the chroma block, among adjacent pixels of the chroma block, the chroma value of the chroma pixel at the preset position is obtained.
  • the corresponding relationship between the preset intra prediction mode and the position can be obtained, and in this correspondence relationship, the prediction corresponding to the intra prediction mode of the chroma block is determined.
  • Set location Then use the preset position to obtain the chromaticity value of the chromaticity pixel at the preset position among the adjacent pixels of the chromaticity block.
  • the position coordinates of the adjacent upper pixels of the chroma block are (0, -1), (1, -1), ..., (X-1, -1) and The position coordinates of adjacent left pixels of the chroma block are (-1, 0), (-1, 1), ..., (-1, Y-1), where X represents the chroma block The width of Y indicates the height of the chroma block.
  • the intra prediction mode corresponding to the chroma block is a cross-component linear mode LM
  • the position coordinates of the chroma pixel at the preset position are (0, -1) (X-1, -1), (- 1, 0), (-1, Y-1).
  • a plane rectangular coordinate is established corresponding to the chroma block, the first chroma pixel in the upper left corner of the chroma block is used as the origin of the coordinate, and the horizontal right is the positive direction of the x-axis, and the vertical is The bottom is the positive direction of the y-axis.
  • the position coordinates of the adjacent upper pixels of the chroma block are (0, -1), (1, -1), ..., (X-1, -1), the adjacent left pixels of the chroma block
  • the position coordinates are (-1, 0), (-1, 1), ..., (-1, Y-1)
  • X represents the width of the chroma block (that is, the number of pixels in the width direction of the chroma block)
  • Y represents the height of the chroma block (that is, the number of pixels in the height direction of the chroma block).
  • the intra prediction mode is LM
  • the position coordinates of the chroma pixel at the preset position are (0, -1) (X-1, -1), (-1, 0), (-1, Y-1).
  • the position coordinates of adjacent upper pixels of the chroma block are (0, -1), (1, -1), ..., (X-1, -1), Wherein, X represents the width of the chroma block.
  • the intra prediction mode corresponding to the chroma block is the cross-component upper linear mode LMA
  • the position coordinates of the preset position are (0, -1), (X/4, -1), (X- 1-X/4, -1), (X-1, -1), or (0, -1) (X/4, -1) (3*X/4, -1) (X-1,- 1).
  • a plane rectangular coordinate is established corresponding to the chroma block, the first chroma pixel in the upper left corner of the chroma block is used as the origin of the coordinate, and the horizontal right is the positive direction of the x-axis, and the vertical is The bottom is the positive direction of the y-axis.
  • the position coordinates of the preset position are (0, -1), (X/4, -1), (X-1-X/4, -1), (X-1,- 1), or (0, -1) (X/4, -1) (3*X/4, -1) (X-1, -1), X represents the width of the chroma block (that is, the The number of pixels in the width direction).
  • the position coordinates of adjacent left pixels of the chroma block are (-1, 0), (-1, 1), ..., (-1, Y-1), Where Y represents the height of the chroma block.
  • the intra prediction mode corresponding to the chroma block is the cross-component left linear mode LML
  • the position coordinates of the preset position are (-1, 0) (-1, Y/4) (-1, Y -1-Y/4)(-1,Y-1), or (-1,0)(-1,Y/4)(-1,3*Y/4)(-1,Y-1).
  • a plane rectangular coordinate is established corresponding to the chroma block, the first chroma pixel in the upper left corner of the chroma block is used as the origin of the coordinate, and the horizontal right is the positive direction of the x-axis, and the vertical is The bottom is the positive direction of the y-axis.
  • the position coordinates of the preset position are (-1, 0) (-1, Y/4) (-1, Y-1-Y/4) (-1, Y-1), Or (-1, 0) (-1, Y/4) (-1, 3*Y/4) (-1, Y-1), Y represents the height of the chroma block (that is, in the height direction of the chroma block The number of pixels).
  • the acquiring the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position from the neighboring pixels of the brightness block corresponding to the chroma block includes: Among the adjacent pixels of the luminance block, it is determined that the position coordinate of the luminance pixel corresponding to the chroma pixel at the i-th preset position in the preset position is (2*X i , 2*Y i ), wherein, the The position coordinates of the chromaticity pixels of the i preset positions are (X i , Y i ), and from the position coordinates of the brightness pixels corresponding to the chromaticity pixels of the preset position, from the Among adjacent pixels, obtain the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position; or, according to the position coordinates of the jth preset position in the preset position, at the neighbor of the brightness block Among the pixels, determine the position coordinates of the plurality of sampling points
  • the position coordinates of the chroma pixel at the i-th preset position in the preset position are (X i , Y i ), which can be Among the neighboring pixels, the position coordinates of the luminance pixel corresponding to the chroma pixel at the i-th preset position are determined as (2*X i , 2*Y i ). In this way, the position coordinates of the luminance pixel corresponding to the chroma pixel at the preset position can be obtained.
  • the position coordinates of the chroma pixel at the jth preset position in the preset position are (X j , Y j ), and for the chroma pixel at the jth preset position, Determine (X j , Y j ) multiple sampling point positions corresponding to adjacent pixels of the luminance block, and then based on the position coordinates of the multiple sampling point positions, obtain the luminance pixel corresponding to the chroma pixel at the jth preset position Location coordinates.
  • a weighted method can be used, and the position coordinates of multiple sampling points can be: (2*Xj,2*Yj), (2*Xj,2*Yj+1), (2*Xj+1,2* Yj), (2*Xj+1,2*Yj+1), (2*Xj+2,2*Yj), (2*Xj+2,2*Yj+1), corresponding to the position of each sampling point
  • a weight which is 2/8, 1/8, 1/8, 2/8, 1/8, 1/8, 1/8, after weighting, you can get the chroma pixel corresponding to the jth preset position
  • the position coordinates of the luminance pixels are (2*Xj, 2*Yj+0.5).
  • the weighting method may not be used, and the embodiments of the present application are not limited.
  • the position coordinates of the luminance pixel corresponding to the chroma pixel at the preset position can be obtained.
  • the position coordinates of the brightness pixel corresponding to the chroma pixel at the preset position can be used to obtain the brightness value from the corresponding brightness pixel.
  • the brightness value can be determined more quickly.
  • the indication information is obtained.
  • the indication information indicating the intra prediction mode may be encoded into the code stream, and then sent to the decoding end.
  • the decoding end can obtain the indication information in the received code stream.
  • the decoding side can determine the intra prediction mode used by the chrominance block.
  • the dividing the obtained brightness value into the first brightness set and the second brightness set includes: determining an average value of the brightness values of the brightness pixels corresponding to the chroma pixels at the preset position .
  • the brightness values corresponding to the chrominance pixels at the preset position are less than or equal to the average of the brightness values to form a first brightness set, and the brightness corresponding to the chroma pixels at the preset position is formed Among the brightness values of the pixels, brightness values greater than the average of the brightness values form a second brightness set.
  • the brightness value whose brightness value is less than or equal to the average value of the brightness values among all the brightness values obtained is determined, and these brightness values are grouped into a first brightness set, and all brightness values obtained can be determined
  • the brightness value whose brightness value is greater than the average of the brightness values is composed of these brightness values into a second brightness set, so that the brightness value in the first brightness set is smaller than the brightness value in the second brightness set.
  • the prediction speed of the chroma block can be improved without reducing the encoding performance.
  • the dividing the obtained luminance pixels into a first luminance set and a second luminance set includes: dividing the luminance values of the luminance pixels corresponding to the chroma pixels at the preset position according to Arrange them in a large order to obtain a first brightness value queue; if the number of brightness pixels in the first brightness value queue is an even number, then the first half of the brightness values in the first brightness value queue form the composition A first brightness set, and the brightness values in the second half of the brightness value queue form the second brightness set.
  • the brightness values of the brightness pixels corresponding to the chroma pixels at the preset position in descending order to obtain a second brightness value queue; if the number of brightness pixels in the second brightness value queue If the number is an even number, the brightness values of the second half of the second brightness value queue form the first brightness set, and the brightness values of the first half of the brightness value queue form the second brightness set.
  • the obtained brightness values are arranged in order from small to large to obtain a first brightness value queue. If the number of brightness pixels in the first brightness value queue is an even number, it can be determined The brightness values of the first half of the first brightness value queue form these brightness values into a first brightness set, and the brightness values of the second half of the first brightness value queue can be determined, and these brightness values form a second brightness set. Or, arrange the acquired brightness values in descending order to obtain a second brightness value queue.
  • the second brightness value queue The brightness values of the second half group these brightness values into a first brightness set, and the brightness values of the first half in the second brightness value queue can be determined, and these brightness values are combined into a second brightness set.
  • the prediction speed of the chroma block can be improved without reducing the encoding performance.
  • the average value of the luminance values in the first luminance set, the average value of the luminance values in the second luminance set, and the average value of the chromaticity values in the first chromaticity set includes: Where ⁇ is the scaling factor in the linear model corresponding to the chroma block, C Lmean is the average of the chroma values in the first chroma set, and C Rmean is the chroma values in the second chroma set Mean value, L Lmean is the mean value of the brightness values in the first brightness set, and L Rmean is the mean value of the brightness values in the second brightness set.
  • the determining the offset factor in the linear model corresponding to the chroma block according to the scaling factor includes: according to the scaling factor, the color in the first chroma set The mean value of the degree values and the mean value of the brightness values in the first brightness set determine the offset factor in the linear model corresponding to the chroma block.
  • the solution shown in the embodiment of the present application can determine the average value of the chromaticity values in the first chromaticity set, and can determine the average value of the luminance values in the first luminosity set, and then use the scaling factor and the chromaticity values in the first chromaticity set.
  • the average value of and the average value of the luminance values in the first luminance set determine the offset factor in the linear model corresponding to the chroma block.
  • the determining the offset factor in the linear model corresponding to the chroma block according to the scaling factor includes: according to the scaling factor and the chroma pixel at the preset position The average value of the chromaticity values of and the average value of the luminance values of the luminance pixels corresponding to the chromaticity pixels determine the offset factor in the linear model corresponding to the chromaticity block.
  • the solution shown in the embodiment of the present application can determine the average value of all acquired chromaticity values, and can determine the average value of all acquired luminance values, and then use the scaling factor, the average value of all chromaticity values, and the average value of all luminance values. To determine the offset factor in the linear model corresponding to the chroma block.
  • the determination is made based on the scaling factor, the average value of the chromaticity values of the chroma pixels at the preset position, and the average value of the luminance values of the luminance pixels corresponding to the chroma pixels
  • C mean is the average value of the chroma values of the chroma pixels at the preset position
  • L mean is the average value of the brightness values of the brightness pixels corresponding to the chroma pixels at the preset position.
  • a chroma block prediction apparatus in a second aspect, includes a processor and a memory, where the memory is used to store the processor executable instructions, and the processor implements the instructions to implement the foregoing On the one hand, the chroma block prediction method is provided.
  • a chroma block prediction apparatus includes one or more modules for implementing the chroma block prediction method provided in the first aspect.
  • a computer-readable storage medium stores instructions.
  • the computing device is caused to execute the chroma block provided in the first aspect. Prediction method.
  • a computer program product containing instructions, which when executed on a computing device, causes the computing device to execute the chroma block prediction method provided in the first aspect above.
  • the chromaticity value of the chromaticity pixel at the preset position may be obtained from the adjacent pixels of the chromaticity block, and then from the adjacent pixels of the luminance block corresponding to the chromaticity block , Obtain the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position, divide the obtained brightness value into the first brightness set and the second brightness set, and then divide the corresponding chroma value based on the brightness value grouping There are two sets, namely the first chroma set and the second chroma set.
  • the chromaticity can then be determined according to the average of the luminance values in the first luminance set, the average of the luminance values in the second luminance set, the average of the chromaticity values in the first chromaticity set, and the average of the chromaticity values in the second chromaticity set
  • the scaling factor in the linear model corresponding to the block After determining the scaling factor, you can use the scaling factor to determine the offset factor in the linear model corresponding to the chroma block. Finally, use the scaling factor, the offset factor, and the brightness corresponding to the chroma block. Reconstruct the information and determine the prediction information of the chroma block.
  • a preset number of chrominance values and a preset number of luminance values are selected, and then divided into two luminance sets and two chrominance sets, based on the average value and each color of the luminance values in each luminance set
  • the average of the chroma values in the degree set determines the scaling factor of the brightness block, and then determines the offset factor, and does not use a lot of multiplication, so it can save encoding time and decoding time.
  • FIG. 1 shows a block diagram of an example of a video encoding system for implementing embodiments of the present application
  • FIG. 2 shows a block diagram of an example of a video encoding system including either or both of the encoder 20 of FIG. 3 and the decoder 30 of FIG. 4;
  • FIG. 3 shows a block diagram of an example structure of a video encoder for implementing an embodiment of the present application
  • FIG. 4 shows a block diagram of an example structure for implementing a video decoder according to an embodiment of the present application
  • FIG. 5 is a block diagram showing an example of an encoding device or a decoding device
  • FIG. 6 is a block diagram showing another example of an encoding device or a decoding device
  • Figure 7 shows an example of a YUV format sampling grid
  • FIG. 8 shows an embodiment of the cross-component prediction mode
  • FIG. 11 is a schematic flowchart of a prediction method of a chroma block
  • FIG. 13 is a schematic diagram of chromaticity pixels at preset positions
  • 15 is a schematic diagram of chromaticity pixels at preset positions
  • FIG. 17 is a schematic diagram showing the structure of a chroma block prediction device.
  • Video coding generally refers to processing a sequence of pictures that form a video or video sequence.
  • picture In the field of video coding, the terms “picture”, “frame” or “image” may be used as synonyms.
  • the video encoding used in this application means video encoding or video decoding.
  • Video encoding is performed on the source side and usually includes processing (eg, by compressing) the original video picture to reduce the amount of data required to represent the video picture, thereby storing and/or transmitting more efficiently.
  • Video decoding is performed on the destination side and usually involves inverse processing relative to the encoder to reconstruct the video picture.
  • the “encoding” of video pictures involved in the embodiments should be understood as referring to the “encoding” or “decoding” of video sequences.
  • the combination of the encoding part and the decoding part is also called codec (encoding and decoding, or simply encoding).
  • Each picture of a video sequence is usually divided into non-overlapping block sets, which are usually encoded at the block level.
  • the encoder side usually processes the encoded video at the block (also called image block, or video block) level.
  • the prediction block is generated by spatial (intra-picture) prediction and temporal (inter-picture) prediction, from The current block (the currently processed or to-be-processed block) is subtracted from the prediction block to obtain the residual block.
  • the residual block is transformed in the transform domain and the residual block is quantized to reduce the amount of data to be transmitted (compressed), and the decoder side will The inverse processing part relative to the encoder is applied to the encoded or compressed block to reconstruct the current block for representation.
  • the encoder duplicates the decoder processing loop so that the encoder and decoder generate the same prediction (eg, intra prediction and inter prediction) and/or reconstruction for processing, ie, encoding subsequent blocks.
  • block may be part of a picture or frame. This application defines the following key terms:
  • Current block refers to the block currently being processed. For example, in coding, it refers to the block currently being coded; in decoding, it refers to the block currently being decoded. If the currently processed block is a chroma component block, it is called the current chroma block.
  • the brightness block corresponding to the current chroma block may be referred to as the current brightness block.
  • Reference block refers to a block that provides a reference signal for the current block. During the search process, multiple reference blocks can be traversed to find the best reference block.
  • Predicted block The block that provides prediction for the current block is called the predicted block. For example, after traversing multiple reference blocks, the best reference block is found. This best reference block will provide a prediction for the current block. This block is called a prediction block.
  • Image block signal the pixel value or sample value or sample signal in the image block.
  • Predicted signal The pixel value or sampled value or sampled signal in the predicted block is called the predicted signal.
  • the embodiments of the encoder 20, the decoder 30, and the encoding system 10 are described below based on FIGS. 1 and 2 to 4.
  • FIG. 1 is a conceptual or schematic block diagram illustrating an exemplary encoding system 10, for example, a video encoding system 10 that can utilize the technology of the present application (this disclosure).
  • the encoder 20 eg, video encoder 20
  • decoder 30 eg, video decoder 30
  • the encoding system 10 includes a source device 12 for providing encoded data 13, for example, encoded pictures 13, to a destination device 14 that decodes encoded data 13, for example.
  • the source device 12 includes an encoder 20, and optionally, may also include a picture source 16, such as a pre-processing unit 18 of a picture pre-processing unit 18, and a communication interface or communication unit 22.
  • a picture source 16 such as a pre-processing unit 18 of a picture pre-processing unit 18, and a communication interface or communication unit 22.
  • the image source 16 may include or may be any type of image capture device, for example, for capturing real-world images, and/or any type of image or comment (for screen content encoding, some text on the screen is also considered to be an image to be encoded Or a part of the image) generating device, for example, a computer graphics processor for generating computer animation pictures, or for acquiring and/or providing real-world pictures, computer animation pictures (for example, screen content, virtual reality (VR) ) Pictures) in any category of equipment, and/or any combination thereof (eg, augmented reality (AR) pictures).
  • image capture device for example, for capturing real-world images, and/or any type of image or comment (for screen content encoding, some text on the screen is also considered to be an image to be encoded Or a part of the image) generating device, for example, a computer graphics processor for generating computer animation pictures, or for acquiring and/or providing real-world pictures, computer animation pictures (for example, screen content, virtual reality (VR) ) Pictures) in any category
  • the picture can be regarded as a two-dimensional array or matrix of sampling points with luminance values.
  • the sampling points in the array may also be called pixels (short for picture element) or pixels (pel).
  • the number of sampling points in the horizontal and vertical directions (or axes) of the array or picture defines the size and/or resolution of the picture.
  • three color components are usually used, that is, a picture can be represented or contain three sampling arrays.
  • the picture includes corresponding red, green and blue sampling arrays.
  • each pixel is usually expressed in a luma/chroma format or color space, for example, YCbCr, including the luminance component indicated by Y (sometimes also indicated by L) and the two chromaticities indicated by Cb and Cr Weight.
  • the luminance (abbreviated as luma) component Y represents the luminance or gray level intensity (for example, in grayscale pictures, the two are the same), while the two chroma (abbreviated as chroma) components Cb and Cr represent the chroma or color information component .
  • the YCbCr format picture includes a luminance sampling array of luminance sampling values (Y), and two chrominance sampling arrays of chrominance values (Cb and Cr). RGB format pictures can be converted or transformed into YCbCr format, and vice versa, this process is also called color transformation or conversion. If the picture is black shell, the picture may include only the brightness sampling array.
  • the picture source 16 may be, for example, a camera for capturing pictures, a memory such as a picture memory, including or storing previously captured or generated pictures, and/or any category (internal) of acquiring or receiving pictures Or external) interface.
  • the camera may be, for example, an integrated camera local or integrated in the source device, and the memory may be an integrated memory local or for example integrated in the source device.
  • the interface may be, for example, an external interface that receives pictures from an external video source.
  • the external video source is, for example, an external picture capture device, such as a camera, external memory, or external picture generation device.
  • the external picture generation device is, for example, an external computer graphics processor, computer Or server.
  • the interface may be any type of interface according to any proprietary or standardized interface protocol, such as a wired or wireless interface, an optical interface.
  • the interface for acquiring the picture data 17 may be the same interface as the communication interface 22 or a part of the communication interface 22.
  • the picture or picture data 17 may also be referred to as the original picture or the original picture data 17.
  • the pre-processing unit 18 is used to receive (original) picture data 17 and perform pre-processing on the picture data 17 to obtain the pre-processed picture 19 or the pre-processed picture data 19.
  • the preprocessing performed by the preprocessing unit 18 may include trimming, color format conversion (for example, conversion from RGB to YCbCr), color adjustment, or denoising. It can be understood that the pre-processing unit 18 may be an optional component.
  • An encoder 20 (eg, video encoder 20) is used to receive pre-processed picture data 19 and provide encoded picture data 21 (details will be described further below, for example, based on FIG. 3 or FIG. 5).
  • the encoder 20 may be used to implement the following embodiments one to seven.
  • the communication interface 22 of the source device 12 may be used to receive the encoded picture data 21 and transmit it to other devices, for example, the destination device 14 or any other device, for storage or direct reconstruction, or for storing the corresponding
  • the encoded data 13 and/or the encoded picture data 21 is processed before transmission of the encoded data 13 to other devices, such as the destination device 14 or any other device for decoding or storage.
  • the destination device 14 includes a decoder 30 (for example, a video decoder 30), and optionally, may also include a communication interface or communication unit 28, a post-processing unit 32, and a display device 34.
  • a decoder 30 for example, a video decoder 30
  • a communication interface or communication unit 28 may also include a communication interface or communication unit 28, a post-processing unit 32, and a display device 34.
  • the communication interface 28 of the destination device 14 is used, for example, to receive the encoded picture data 21 or the encoded data 13 directly from the source device 12 or any other source, such as a storage device, and the storage device such as an encoded picture data storage equipment.
  • the communication interface 22 and the communication interface 28 can be used for direct communication through the direct communication link between the source device 12 and the destination device 14 or through any type of network to transmit or receive the encoded picture data 21 or the encoded data 13
  • the link is, for example, a direct wired or wireless connection, and any kind of network is, for example, a wired or wireless network or any combination thereof, or any kind of private and public networks, or any combination thereof.
  • the communication interface 22 may be used, for example, to encapsulate the encoded picture data 21 into a suitable format, such as a packet, for transmission on a communication link or communication network.
  • the communication interface 28 forming the corresponding part of the communication interface 22 may be used, for example, to depacketize the encoded data 13 to obtain the encoded picture data 21.
  • Both the communication interface 22 and the communication interface 28 may be configured as a one-way communication interface, as indicated by the arrow for the encoded picture data 13 from the source device 12 to the destination device 14 in FIG. 1, or as a two-way communication interface, and It can be used, for example, to send and receive messages to establish connections, confirm and exchange any other information related to the communication link and/or data transmission such as the transmission of encoded picture data.
  • the decoder 30 is used to receive the encoded picture data 21 and provide the decoded picture data 31 or the decoded picture 31 (details will be described further below, for example, based on FIG. 4 or FIG. 6 ). In one example, the decoder 30 may be used to perform the following embodiments one to seven.
  • the post-processor 32 of the destination device 14 is used to post-process decoded picture data 31 (also referred to as reconstructed picture data), for example, decoded picture 131, to obtain post-processed picture data 33, for example, post-processing Picture 33.
  • the post-processing performed by the post-processing unit 32 may include, for example, color format conversion (for example, conversion from YCbCr to RGB), color adjustment, trimming, or resampling, or any other processing for, for example, preparing the decoded picture data 31 to The display device 34 displays.
  • the display device 34 of the destination device 14 is used to receive post-processed picture data 33 to display pictures to, for example, a user or a viewer.
  • the display device 34 may be or may include any type of display for presenting reconstructed pictures, for example, an integrated or external display or monitor.
  • the display may include a liquid crystal display (liquid crystal display (LCD), an organic light emitting diode (OLED) display, a plasma display, a projector, a micro LED display, a liquid crystal on silicon (LCoS), Digital light processor (digital light processor, DLP) or any other type of display.
  • FIG. 1 depicts source device 12 and destination device 14 as separate devices
  • device embodiments may also include both source device 12 and destination device 14 or the functionality of both, ie source device 12 or corresponding And the destination device 14 or the corresponding functionality.
  • the same hardware and/or software may be used, or separate hardware and/or software, or any combination thereof may be used to implement the source device 12 or corresponding functionality and the destination device 14 or corresponding functionality .
  • Both the encoder 20 and the decoder 30 may be implemented as any of various suitable circuits, for example, one or more microprocessors, digital signal processors (digital signal processor, DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), discrete logic, hardware, or any combination thereof.
  • the device may store the instructions of the software in a suitable non-transitory computer-readable storage medium, and may use one or more processors to execute the instructions in hardware to perform the techniques of the present disclosure . Any one of the foregoing (including hardware, software, a combination of hardware and software, etc.) may be regarded as one or more processors.
  • Each of the video encoder 20 and the video decoder 30 may be included in one or more encoders or decoders, any of which may be integrated as a combined encoder/decoder in the corresponding device Part of the codec (codec).
  • the source device 12 may be referred to as a video encoding device or a video encoding device.
  • the destination device 14 may be referred to as a video decoding device or a video decoding device.
  • the source device 12 and the destination device 14 may be examples of video encoding devices or video encoding devices.
  • Source device 12 and destination device 14 may include any of a variety of devices, including any type of handheld or stationary device, such as a notebook or laptop computer, mobile phone, smart phone, tablet or tablet computer, camera, desktop Computers, set-top boxes, televisions, display devices, digital media players, video game consoles, video streaming devices (such as content service servers or content distribution servers), broadcast receiver devices, broadcast transmitter devices, etc., and may not be used Or use any kind of operating system.
  • a notebook or laptop computer mobile phone, smart phone, tablet or tablet computer, camera, desktop Computers, set-top boxes, televisions, display devices, digital media players, video game consoles, video streaming devices (such as content service servers or content distribution servers), broadcast receiver devices, broadcast transmitter devices, etc., and may not be used Or use any kind of operating system.
  • source device 12 and destination device 14 may be equipped for wireless communication. Therefore, the source device 12 and the destination device 14 may be wireless communication devices.
  • the video encoding system 10 shown in FIG. 1 is only an example, and the technology of the present application may be applied to a video encoding setting (for example, video encoding or video decoding) that does not necessarily include any data communication between encoding and decoding devices.
  • data may be retrieved from local storage, streamed on the network, and so on.
  • the video encoding device may encode the data and store the data to the memory, and/or the video decoding device may retrieve the data from the memory and decode the data.
  • encoding and decoding are performed by devices that do not communicate with each other but only encode data to and/or retrieve data from memory and decode the data.
  • video decoder 30 may be used to perform the reverse process.
  • the video decoder 30 may be used to receive and parse such syntax elements, and decode relevant video data accordingly.
  • video encoder 20 may entropy encode syntax elements into an encoded video bitstream. In such instances, video decoder 30 may parse such syntax elements and decode relevant video data accordingly.
  • FIG. 2 is an explanatory diagram of an example of a video encoding system 40 including the encoder 20 of FIG. 3 and/or the decoder 30 of FIG. 4 according to an exemplary embodiment.
  • the system 40 can implement a combination of various technologies of the present application.
  • the video encoding system 40 may include an imaging device 41, a video encoder 20, a video decoder 30 (and/or a video encoder implemented by the logic circuit 47 of the processing unit 46), an antenna 42, One or more processors 43, one or more memories 44, and/or display devices 45.
  • the imaging device 41, the antenna 42, the processing unit 46, the logic circuit 47, the video encoder 20, the video decoder 30, the processor 43, the memory 44, and/or the display device 45 can communicate with each other.
  • video encoding system 40 is shown with video encoder 20 and video decoder 30, in different examples, video encoding system 40 may include only video encoder 20 or only video decoder 30.
  • the video encoding system 40 may include an antenna 42.
  • the antenna 42 may be used to transmit or receive an encoded bit stream of video data.
  • video encoding system 40 may include display device 45.
  • the display device 45 may be used to present video data.
  • the logic circuit 47 may be implemented by the processing unit 46.
  • the processing unit 46 may include application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, and the like.
  • the video encoding system 40 may also include an optional processor 43, which may similarly include application specific integrated circuit logic, a graphics processor, a general-purpose processor, and the like.
  • the logic circuit 47 may be implemented by hardware, such as dedicated hardware for video encoding, etc., and the processor 43 may be implemented by general-purpose software, an operating system, or the like.
  • the memory 44 may be any type of memory, such as volatile memory (for example, static random access memory (Static Random Access Memory, SRAM), dynamic random access memory (Dynamic Random Access Memory, DRAM), etc.) or non-volatile Memory (for example, flash memory, etc.), etc.
  • the memory 44 may be implemented by cache memory.
  • logic circuit 47 may access memory 44 (e.g., to implement an image buffer).
  • the logic circuit 47 and/or the processing unit 46 may include memory (eg, cache, etc.) for implementing image buffers, etc.
  • the video encoder 20 implemented by a logic circuit may include an image buffer (eg, implemented by the processing unit 46 or the memory 44) and a graphics processing unit (eg, implemented by the processing unit 46).
  • the graphics processing unit may be communicatively coupled to the image buffer.
  • the graphics processing unit may include the video encoder 20 implemented by a logic circuit 47 to implement the various modules discussed with reference to FIG. 2 and/or any other encoder system or subsystem described herein.
  • Logic circuits can be used to perform the various operations discussed herein.
  • Video decoder 30 may be implemented by logic circuit 47 in a similar manner to implement the various modules discussed with reference to decoder 30 of FIG. 4 and/or any other decoder systems or subsystems described herein.
  • the video decoder 30 implemented by the logic circuit may include an image buffer (implemented by the processing unit 2820 or the memory 44) and a graphics processing unit (for example, implemented by the processing unit 46).
  • the graphics processing unit may be communicatively coupled to the image buffer.
  • the graphics processing unit may include a video decoder 30 implemented by a logic circuit 47 to implement various modules discussed with reference to FIG. 4 and/or any other decoder system or subsystem described herein.
  • the antenna 42 of the video encoding system 40 may be used to receive the encoded bitstream of video data.
  • the encoded bitstream may include data related to encoded video frames, indicators, index values, mode selection data, etc. discussed herein, such as data related to encoded partitions (eg, transform coefficients or quantized transform coefficients , (As discussed) optional indicators, and/or data defining the code segmentation).
  • the video encoding system 40 may also include a video decoder 30 coupled to the antenna 42 and used to decode the encoded bitstream.
  • the display device 45 is used to present video frames.
  • FIG. 3 shows a schematic/conceptual block diagram of an example of a video encoder 20 for implementing the technology of the present application (disclosure).
  • the video encoder 20 includes a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a buffer 216, loop filtering A unit 220, a decoded picture buffer (DPB) 230, a prediction processing unit 260, and an entropy encoding unit 270.
  • the prediction processing unit 260 may include an inter prediction unit 244, an intra prediction unit 254, and a mode selection unit 262.
  • the inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown).
  • the video encoder 20 shown in FIG. 3 may also be referred to as a hybrid video encoder or a video encoder based on a hybrid video codec.
  • the residual calculation unit 204, the transform processing unit 206, the quantization unit 208, the prediction processing unit 260, and the entropy encoding unit 270 form the forward signal path of the encoder 20, while, for example, the inverse quantization unit 210, the inverse transform processing unit 212, the heavy
  • the construction unit 214, the buffer 216, the loop filter 220, the decoded picture buffer 230, and the prediction processing unit 260 form a backward signal path of the encoder, where the backward signal path of the encoder corresponds to the signal path of the decoder (See decoder 30 in FIG. 4).
  • the encoder 20 receives a picture 201 or a block 203 of a picture 201 through, for example, an input 202, for example, forming a picture in a picture sequence of a video or a video sequence.
  • the picture block 203 may also be called a current picture block or a picture block to be encoded
  • the picture 201 may be called a current picture or a picture to be encoded (especially when the current picture is distinguished from other pictures in video encoding, the other pictures are the same video sequence, for example That is, the previously encoded and/or decoded pictures in the video sequence of the current picture are also included).
  • An embodiment of the encoder 20 may include a division unit (not shown in FIG. 3) for dividing the picture 201 into a plurality of blocks such as block 203, usually into a plurality of non-overlapping blocks.
  • the segmentation unit can be used to use the same block size and corresponding grids that define the block size for all pictures in the video sequence, or to change the block size between pictures or subsets or picture groups, and divide each picture into The corresponding block.
  • the prediction processing unit 260 of the video encoder 20 may be used to perform any combination of the above-mentioned partitioning techniques.
  • block 203 is also or can be regarded as a two-dimensional array or matrix of sampling points with luminance values (sample values), although its size is smaller than picture 201.
  • the block 203 may include, for example, a sampling array (for example, a brightness array in the case of black and white pictures 201) or three sampling arrays (for example, a brightness array and two chroma arrays in the case of color pictures) or basis An array of any other number and/or category of color formats applied.
  • the number of sampling points in the horizontal and vertical direction (or axis) of the block 203 defines the size of the block 203.
  • the encoder 20 shown in FIG. 3 is used to encode the picture 201 block by block, for example, to perform encoding and prediction on each block 203.
  • the residual calculation unit 204 is used to calculate the residual block 205 based on the picture block 203 and the prediction block 265 (further details of the prediction block 265 are provided below), for example, by subtracting the prediction from the sample value of the picture block 203 by sample (pixel by pixel) The sample values of block 265 to obtain the residual block 205 in the sample domain.
  • the transform processing unit 206 is used to apply a transform such as discrete cosine transform (DCT) or discrete sine transform (DST) to the sample values of the residual block 205 to obtain transform coefficients 207 in the transform domain .
  • the transform coefficient 207 may also be called a transform residual coefficient, and represents a residual block 205 in the transform domain.
  • the transform processing unit 206 may be used to apply integer approximations of DCT/DST, such as the transform specified by HEVC/H.265. Compared with the orthogonal DCT transform, this integer approximation is usually scaled by a factor. In order to maintain the norm of the residual block processed by the forward and inverse transform, an additional scaling factor is applied as part of the transform process.
  • the scaling factor is usually selected based on certain constraints, for example, the scaling factor is a power of two used for the shift operation, the bit depth of the transform coefficient, the accuracy, and the trade-off between implementation cost, and so on.
  • a specific scaling factor can be specified for the inverse transform by the inverse transform processing unit 212 on the decoder 30 side (and a corresponding inverse transform by the inverse transform processing unit 212 on the encoder 20 side), and accordingly, The 20 side specifies the corresponding scaling factor for the positive transform by the transform processing unit 206.
  • the quantization unit 208 is used to quantize the transform coefficient 207 by, for example, applying scalar quantization or vector quantization to obtain the quantized transform coefficient 209.
  • the quantized transform coefficient 209 may also be referred to as the quantized residual coefficient 209.
  • the quantization process can reduce the bit depth associated with some or all of the transform coefficients 207. For example, n-bit transform coefficients can be rounded down to m-bit transform coefficients during quantization, where n is greater than m.
  • the degree of quantization can be modified by adjusting quantization parameters (QP). For example, for scalar quantization, different scales can be applied to achieve thinner or coarser quantization.
  • QP quantization parameters
  • a smaller quantization step size corresponds to a finer quantization
  • a larger quantization step size corresponds to a coarser quantization.
  • the appropriate quantization step size can be indicated by the quantization parameter.
  • the quantization parameter may be an index of a predefined set of suitable quantization steps.
  • smaller quantization parameters may correspond to fine quantization (smaller quantization step size)
  • larger quantization parameters may correspond to coarse quantization (larger quantization step size)
  • the quantization may include dividing by the quantization step size and the corresponding quantization or inverse quantization performed by, for example, inverse quantization 210, or may include multiplying the quantization step size.
  • Embodiments according to some standards such as HEVC may use quantization parameters to determine the quantization step size.
  • the quantization step size can be calculated based on the quantization parameter using a fixed-point approximation including an equation of division. Additional scaling factors can be introduced for quantization and inverse quantization to restore the norm of the residual block that may be modified due to the scale used in fixed-point approximation of the equations for quantization step size and quantization parameter.
  • the scale of inverse transform and inverse quantization may be combined.
  • a custom quantization table can be used and signaled from the encoder to the decoder in a bitstream, for example. Quantization is a lossy operation, where the larger the quantization step, the greater the loss.
  • the inverse quantization unit 210 is used to apply the inverse quantization of the quantization unit 208 on the quantized coefficients to obtain the inverse quantized coefficients 211, for example, based on or using the same quantization step size as the quantization unit 208, apply the quantization scheme applied by the quantization unit 208 Inverse quantization scheme.
  • the inverse quantized coefficient 211 may also be referred to as an inverse quantized residual coefficient 211, which corresponds to the transform coefficient 207, although the loss due to quantization is usually not the same as the transform coefficient.
  • the inverse transform processing unit 212 is used to apply the inverse transform of the transform applied by the transform processing unit 206, for example, inverse discrete cosine transform or inverse discrete sine transform, to obtain the inverse transform block 213 in the sample domain.
  • the inverse transform block 213 may also be referred to as an inverse transform dequantized block 213 or an inverse transform residual block 213.
  • the reconstruction unit 214 (eg, summer 214) is used to add the inverse transform block 213 (ie, the reconstructed residual block 213) to the prediction block 265 to obtain the reconstructed block 215 in the sample domain, for example, The sample values of the reconstructed residual block 213 and the sample values of the prediction block 265 are added.
  • a buffer unit 216 (or simply "buffer" 216), such as a line buffer 216, is used to buffer or store the reconstructed block 215 and corresponding sample values for, for example, intra prediction.
  • the encoder may be used to use the unfiltered reconstructed blocks and/or corresponding sample values stored in the buffer unit 216 for any type of estimation and/or prediction, such as intra prediction.
  • an embodiment of the encoder 20 may be configured such that the buffer unit 216 is used not only to store the reconstructed block 215 for intra prediction 254, but also for the loop filter unit 220 (not shown in FIG. 3) Out), and/or, for example, causing the buffer unit 216 and the decoded picture buffer unit 230 to form a buffer.
  • Other embodiments may be used to use the filtered block 221 and/or blocks or samples from the decoded picture buffer 230 (neither shown in FIG. 3) as an input or basis for intra prediction 254.
  • the loop filter unit 220 (or simply “loop filter” 220) is used to filter the reconstructed block 215 to obtain the filtered block 221, so as to smoothly perform pixel conversion or improve video quality.
  • the loop filter unit 220 is intended to represent one or more loop filters, such as deblocking filters, sample-adaptive offset (SAO) filters, or other filters, such as bilateral filters, Adaptive loop filter (adaptive loop filter, ALF), or sharpening or smoothing filter, or collaborative filter.
  • the loop filter unit 220 is shown as an in-loop filter in FIG. 3, in other configurations, the loop filter unit 220 may be implemented as a post-loop filter.
  • the filtered block 221 may also be referred to as the filtered reconstructed block 221.
  • the decoded picture buffer 230 may store the reconstructed coding block after the loop filter unit 220 performs a filtering operation on the reconstructed coding block.
  • Embodiments of the encoder 20 may be used to output loop filter parameters (eg, sample adaptive offset information), for example, directly output or by the entropy encoding unit 270 or any other
  • the entropy encoding unit outputs after entropy encoding, for example, so that the decoder 30 can receive and apply the same loop filter parameters for decoding.
  • the decoded picture buffer 230 may be a reference picture memory that stores reference picture data for the video encoder 20 to encode video data.
  • DPB 230 can be formed by any of a variety of memory devices, such as dynamic random access memory (dynamic random access memory, DRAM) (including synchronous DRAM (synchronous DRAM, SDRAM), magnetoresistive RAM (magnetoresistive RAM, MRAM), resistive RAM (resistive RAM, RRAM)) or other types of memory devices.
  • DRAM dynamic random access memory
  • DRAM dynamic random access memory
  • MRAM magnetoresistive RAM
  • RRAM resistive RAM
  • the DPB 230 and the buffer 216 may be provided by the same memory device or separate memory devices.
  • a decoded picture buffer (DPB) 230 is used to store the filtered block 221.
  • the decoded picture buffer 230 may be further used to store other previous filtered blocks of the same current picture or different pictures such as previous reconstructed pictures, such as the previously reconstructed and filtered block 221, and may provide the complete previous The reconstructed ie decoded pictures (and corresponding reference blocks and samples) and/or partially reconstructed current pictures (and corresponding reference blocks and samples), for example for inter prediction. In some example, if the reconstructed block 215 is reconstructed without in-loop filtering, the decoded picture buffer 230 is used to store the reconstructed block 215.
  • the prediction processing unit 260 also known as the block prediction processing unit 260, is used to receive or acquire the block 203 (the current block 203 of the current picture 201) and the reconstructed picture data, such as the reference of the same (current) picture from the buffer 216 Samples and/or reference picture data 231 of one or more previously decoded pictures from the decoded picture buffer 230, and used to process such data for prediction, that is, to provide an inter-predicted block 245 or an intra-frame The prediction block 265 of the prediction block 255.
  • the mode selection unit 262 may be used to select a prediction mode (eg, intra or inter prediction mode) and/or the corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.
  • a prediction mode eg, intra or inter prediction mode
  • the corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.
  • An embodiment of the mode selection unit 262 may be used to select a prediction mode (for example, from those prediction modes supported by the prediction processing unit 260), which provides the best match or the minimum residual (the minimum residual means Better compression in transmission or storage), or provide minimum signaling overhead (minimum signaling overhead means better compression in transmission or storage), or consider or balance both at the same time.
  • the mode selection unit 262 may be used to determine the prediction mode based on Rate Distortion Optimization (RDO), that is, select the prediction mode that provides the minimum rate distortion optimization, or select the prediction mode in which the related rate distortion at least meets the prediction mode selection criteria .
  • RDO Rate Distortion Optimization
  • the encoder 20 is used to determine or select the best or optimal prediction mode from the (predetermined) prediction mode set.
  • the set of prediction modes may include, for example, intra prediction modes and/or inter prediction modes.
  • the intra prediction mode set may include 35 different intra prediction modes, or may include 67 different intra prediction modes, or may include the intra prediction modes defined in H.266 in development.
  • the set of inter prediction modes depends on the available reference pictures (ie, for example, the aforementioned at least partially decoded pictures stored in the DBP 230) and other inter prediction parameters, for example, depending on whether to use the entire reference picture or only a part of the reference picture, For example, a search window area surrounding the area of the current block to search for the best matching reference block, and/or for example depending on whether pixel interpolation such as half-pixel and/or quarter-pixel interpolation is applied.
  • skip mode and/or direct mode can also be applied.
  • the prediction processing unit 260 may be further used to split the block 203 into smaller block partitions or sub-blocks, for example, iteratively use quad-tree (QT) splitting, binary-tree (BT) splitting or Triple-tree (TT) partitioning, or any combination thereof, and for performing predictions for each of block partitions or sub-blocks, for example, where mode selection includes selecting the tree structure of the partitioned block 203 and the selection applied to the block The prediction mode of each of the partitions or sub-blocks.
  • QT quad-tree
  • BT binary-tree
  • TT Triple-tree
  • the inter prediction unit 244 may include a motion estimation (ME) unit (not shown in FIG. 3) and a motion compensation (MC) unit (not shown in FIG. 3).
  • the motion estimation unit is used to receive or acquire the picture block 203 (current picture block 203 of the current picture 201) and the decoded picture 231, or at least one or more previously reconstructed blocks, for example, one or more other/different previous warp
  • the reconstructed block of the picture 231 is decoded to perform motion estimation.
  • the video sequence may include the current picture and the previously decoded picture 31, or in other words, the current picture and the previously decoded picture 31 may be part of or form a sequence of pictures that form the video sequence.
  • the encoder 20 may be used to select a reference block from multiple reference blocks of the same or different pictures in multiple other pictures, and provide a reference picture and/or provide a reference to a motion estimation unit (not shown in FIG. 3)
  • the offset (spatial offset) between the position of the block (X, Y coordinates) and the position of the current block is used as an inter prediction parameter. This offset is also called motion vector (MV).
  • the motion compensation unit is used to acquire, for example, receive inter prediction parameters, and perform inter prediction based on or using inter prediction parameters to obtain inter prediction blocks 245.
  • the motion compensation performed by the motion compensation unit may include extracting or generating a prediction block based on a motion/block vector determined by motion estimation (possibly performing interpolation of sub-pixel accuracy). Interpolation filtering can generate additional pixel samples from known pixel samples, potentially increasing the number of candidate prediction blocks that can be used to encode picture blocks.
  • the motion compensation unit 246 may locate the prediction block pointed to by the motion vector in a reference picture list. Motion compensation unit 246 may also generate syntax elements associated with blocks and video slices for use by video decoder 30 when decoding picture blocks of video slices.
  • the intra prediction unit 254 is used to acquire, for example, a picture block 203 (current picture block) that receives the same picture and one or more previously reconstructed blocks, such as reconstructed neighboring blocks, for intra estimation.
  • the encoder 20 may be used to select an intra prediction mode from multiple intra prediction modes.
  • Embodiments of the encoder 20 may be used to select an intra prediction mode based on optimization criteria, for example, based on a minimum residual (eg, an intra prediction mode that provides the prediction block 255 most similar to the current picture block 203) or minimum rate distortion.
  • a minimum residual eg, an intra prediction mode that provides the prediction block 255 most similar to the current picture block 203
  • minimum rate distortion e.g., a minimum rate distortion
  • the intra prediction unit 254 is further used to determine the intra prediction block 255 based on the intra prediction parameters of the intra prediction mode as selected. In any case, after selecting the intra-prediction mode for the block, the intra-prediction unit 254 is also used to provide the intra-prediction parameters to the entropy encoding unit 270, that is, to provide an indication of the selected intra-prediction mode for the block Information. In one example, the intra prediction unit 254 may be used to perform any combination of intra prediction techniques described below.
  • the entropy coding unit 270 is used to convert the entropy coding algorithm or scheme (for example, variable length coding (VLC) scheme, context adaptive VLC (context adaptive VLC, CAVLC) scheme, arithmetic coding scheme, context adaptive binary arithmetic) Coding (context adaptive) binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partition entropy (probability interval interpartitioning entropy, PIPE) coding or other entropy Coding method or technique) applied to a single or all of the quantized residual coefficients 209, inter prediction parameters, intra prediction parameters, and/or loop filter parameters (or not applied) to obtain the output 272 to For example, the encoded picture data 21 output in the form of an encoded bit stream 21.
  • VLC variable length coding
  • CABAC context adaptive binary arithmetic) Coding
  • SBAC syntax-based context-adaptive binary arithmetic
  • the encoded bitstream can be transmitted to the video decoder 30 or archived for later transmission or retrieval by the video decoder 30.
  • the entropy encoding unit 270 may also be used to entropy encode other syntax elements of the current video slice being encoded.
  • video encoder 20 may be used to encode video streams.
  • the non-transform based encoder 20 may directly quantize the residual signal without the transform processing unit 206 for certain blocks or frames.
  • the encoder 20 may have a quantization unit 208 and an inverse quantization unit 210 combined into a single unit.
  • FIG. 4 shows an exemplary video decoder 30 for implementing the technology of the present application.
  • the video decoder 30 is used to receive encoded picture data (eg, encoded bitstream) 21, for example, encoded by the encoder 20, to obtain the decoded picture 231.
  • encoded picture data eg, encoded bitstream
  • video decoder 30 receives video data from video encoder 20, such as an encoded video bitstream and associated syntax elements representing picture blocks of the encoded video slice.
  • the decoder 30 includes an entropy decoding unit 304, an inverse quantization unit 310, an inverse transform processing unit 312, a reconstruction unit 314 (such as a summer 314), a buffer 316, a loop filter 320, a The decoded picture buffer 330 and the prediction processing unit 360.
  • the prediction processing unit 360 may include an inter prediction unit 344, an intra prediction unit 354, and a mode selection unit 362.
  • video decoder 30 may perform a decoding pass that is generally inverse to the encoding pass described with reference to video encoder 20 of FIG. 3.
  • the entropy decoding unit 304 is used to perform entropy decoding on the encoded picture data 21 to obtain, for example, quantized coefficients 309 and/or decoded encoding parameters (not shown in FIG. 4), for example, inter prediction, intra prediction parameters , Any or all of the loop filter parameters and/or other syntax elements (decoded).
  • the entropy decoding unit 304 is further used to forward inter prediction parameters, intra prediction parameters, and/or other syntax elements to the prediction processing unit 360.
  • Video decoder 30 may receive syntax elements at the video slice level and/or the video block level.
  • the inverse quantization unit 310 may be functionally the same as the inverse quantization unit 110
  • the inverse transform processing unit 312 may be functionally the same as the inverse transform processing unit 212
  • the reconstruction unit 314 may be functionally the same as the reconstruction unit 214
  • the buffer 316 may be functionally
  • the loop filter 320 may be functionally the same as the loop filter 220
  • the decoded picture buffer 330 may be functionally the same as the decoded picture buffer 230.
  • the prediction processing unit 360 may include an inter prediction unit 344 and an intra prediction unit 354, where the inter prediction unit 344 may be similar in function to the inter prediction unit 244, and the intra prediction unit 354 may be similar in function to the intra prediction unit 254 .
  • the prediction processing unit 360 is generally used to perform block prediction and/or obtain the prediction block 365 from the encoded data 21, and to receive or obtain prediction-related parameters and/or information about the entropy decoding unit 304 (explicitly or implicitly). Information about the selected prediction mode.
  • the intra prediction unit 354 of the prediction processing unit 360 is used to signal-based the intra prediction mode and the previous decoded block from the current frame or picture Data to generate a prediction block 365 for the picture block of the current video slice.
  • the inter prediction unit 344 eg, motion compensation unit
  • Other syntax elements generate a prediction block 365 for the video block of the current video slice.
  • a prediction block may be generated from a reference picture in a reference picture list.
  • the video decoder 30 may construct the reference frame lists: list 0 and list 1 using default construction techniques based on the reference pictures stored in the DPB 330.
  • the prediction processing unit 360 is used to determine the prediction information for the video block of the current video slice by parsing the motion vector and other syntax elements, and use the prediction information to generate the prediction block for the current video block being decoded. For example, the prediction processing unit 360 uses some received syntax elements to determine a prediction mode (eg, intra or inter prediction) of a video block used to encode a video slice, an inter prediction slice type (eg, B slice, (P slice or GPB slice), construction information of one or more of the reference picture lists for slices, motion vectors for each inter-coded video block for slices, each warp for slices The inter prediction status and other information of the inter-coded video block to decode the video block of the current video slice.
  • a prediction mode eg, intra or inter prediction
  • an inter prediction slice type eg, B slice, (P slice or GPB slice
  • construction information of one or more of the reference picture lists for slices motion vectors for each inter-coded video block for slices, each warp for slices
  • the inverse quantization unit 310 may be used to inverse quantize (i.e., inverse quantize) the quantized transform coefficients provided in the bitstream and decoded by the entropy decoding unit 304.
  • the inverse quantization process may include using the quantization parameters calculated by the video encoder 20 for each video block in the video slice to determine the degree of quantization that should be applied and also determine the degree of inverse quantization that should be applied.
  • the inverse transform processing unit 312 is used to apply an inverse transform (eg, inverse DCT, inverse integer transform, or conceptually similar inverse transform process) to the transform coefficients to generate a residual block in the pixel domain.
  • an inverse transform eg, inverse DCT, inverse integer transform, or conceptually similar inverse transform process
  • the reconstruction unit 314 (eg, summer 314) is used to add the inverse transform block 313 (ie, the reconstructed residual block 313) to the prediction block 365 to obtain the reconstructed block 315 in the sample domain, for example by The sample values of the reconstructed residual block 313 and the sample values of the prediction block 365 are added.
  • the loop filter unit 320 (during the encoding cycle or after the encoding cycle) is used to filter the reconstructed block 315 to obtain the filtered block 321 to smoothly perform pixel conversion or improve video quality.
  • the loop filter unit 320 may be used to perform any combination of filtering techniques described below.
  • the loop filter unit 320 is intended to represent one or more loop filters, such as deblocking filters, sample-adaptive offset (SAO) filters, or other filters, such as bilateral filters, self-adaptive filters Adaptive loop filter (adaptive loop filter, ALF), or sharpening or smoothing filter, or collaborative filter.
  • the loop filter unit 320 is shown as an in-loop filter in FIG. 4, in other configurations, the loop filter unit 320 may be implemented as a post-loop filter.
  • the decoded video block 321 in a given frame or picture is then stored in a decoded picture buffer 330 that stores reference pictures for subsequent motion compensation.
  • the decoder 30 is used, for example, to output the decoded picture 31 through the output 332 for presentation to the user or for the user to view.
  • video decoder 30 may be used to decode the compressed bitstream.
  • the decoder 30 may generate the output video stream without the loop filter unit 320.
  • the non-transform based decoder 30 may directly inversely quantize the residual signal without the inverse transform processing unit 312 for certain blocks or frames.
  • the video decoder 30 may have an inverse quantization unit 310 and an inverse transform processing unit 312 combined into a single unit.
  • FIG. 5 is a schematic structural diagram of a video decoding device 400 (for example, a video encoding device 400 or a video decoding device 400) according to an embodiment of the present application.
  • the video coding device 400 is suitable for implementing the embodiments described herein.
  • the video coding device 400 may be a video decoder (eg, video decoder 30 of FIG. 1) or a video encoder (eg, video encoder 20 of FIG. 1).
  • the video decoding device 400 may be one or more components in the video decoder 30 of FIG. 1 or the video encoder 20 of FIG. 1 described above.
  • the video decoding device 400 includes: an inlet port 410 for receiving data and a receiving unit (Rx) 420, a processor for processing data, a logic unit or a central processing unit (CPU) 430, and a transmitter unit for transmitting data (Tx) 440 and exit port 450, and a memory 460 for storing data.
  • the video decoding device 400 may further include a photoelectric conversion component and an electro-optical (EO) component coupled to the inlet port 410, the receiver unit 420, the transmitter unit 440, and the outlet port 450 for the outlet or inlet of the optical signal or the electrical signal.
  • EO electro-optical
  • the processor 430 is implemented by hardware and software.
  • the processor 430 may be implemented as one or more CPU chips, cores (eg, multi-core processors), FPGA, ASIC, and DSP.
  • the processor 430 communicates with the inlet port 410, the receiver unit 420, the transmitter unit 440, the outlet port 450, and the memory 460.
  • the processor 430 includes a decoding module 470 (for example, an encoding module 470 or a decoding module 470).
  • the encoding/decoding module 470 implements the embodiments disclosed above. For example, the encoding/decoding module 470 implements, processes, or provides various encoding operations.
  • the encoding/decoding module 470 provides a substantial improvement in the function of the video decoding device 400 and affects the conversion of the video decoding device 400 to different states.
  • the encoding/decoding module 470 is implemented with instructions stored in the memory 460 and executed by the processor 430.
  • the memory 460 includes one or more magnetic disks, tape drives, and solid-state hard disks, and can be used as an overflow data storage device for storing programs when these programs are selectively executed, and for storing instructions and data read during program execution.
  • the memory 460 may be volatile and/or non-volatile, and may be read-only memory (Read Only Memory, ROM), random access memory (random access memory, RAM), random access memory (ternary content-addressable memory, TCAM) and/or static random access memory (SRAM).
  • FIG. 6 is a simplified block diagram of an apparatus 500 that can be used as either or both of the source device 12 and the destination device 14 in FIG. 1 according to an exemplary embodiment.
  • the apparatus 500 may implement the technology of the present application, and the apparatus 500 for implementing chroma block prediction may take the form of a computing system including multiple computing devices, or adopt, for example, a mobile phone, a tablet computer, a laptop computer, a notebook computer, or a desktop The form of a single computing device such as a computer.
  • the processor 502 in the device 500 may be a central processor.
  • the processor 502 may be any other type of device or multiple devices that can manipulate or process information currently or will be developed in the future.
  • FIG. 6 although a single processor such as processor 502 may be used to practice the disclosed embodiments, the use of more than one processor may achieve advantages in speed and efficiency.
  • the memory 504 in the apparatus 500 may be a read-only memory device or a random access memory device. Any other suitable type of storage device may be used as the memory 504.
  • the memory 504 may include code and data 506 accessed by the processor 502 using the bus 512.
  • the memory 504 may further include an operating system 508 and an application program 510, which includes at least one program that permits the processor 502 to perform the methods described herein.
  • the application program 510 may include applications 1 to N, and the applications 1 to N further include video encoding applications that perform the methods described herein.
  • the apparatus 500 may also include additional memory in the form of a secondary memory 514, which may be, for example, a memory card used with a mobile computing device. Because the video communication session may contain a large amount of information, the information may be stored in whole or in part in the secondary memory 514 and loaded into the memory 504 as needed for processing.
  • Device 500 may also include one or more output devices, such as display 518.
  • the display 518 may be a touch-sensitive display that combines a display and a touch-sensitive element operable to sense touch input.
  • the display 518 may be coupled to the processor 502 through the bus 512.
  • other output devices that allow the user to program the device 500 or otherwise use the device 500 or provide other output devices as an alternative to the display 518 may be provided.
  • the display can be implemented in different ways, including through a liquid crystal display, a cathode-ray tube (CRT) display, a plasma display, or a light emitting diode (LED) display, such as Organic LED (organic LED, OLED) display.
  • CTR cathode-ray tube
  • plasma display a plasma display
  • LED light emitting diode
  • OLED Organic LED
  • the apparatus 500 may further include or be in communication with an image sensing device 520, such as a camera or any other image sensing device 520 that can sense an image, such as a camera or an existing or future development This is an image of the user who runs the device 500.
  • the image sensing device 520 may be placed to directly face the user who runs the device 500.
  • the position and optical axis of the image sensing device 520 may be configured so that its field of view includes an area immediately adjacent to the display 518 and the display 518 is visible from the area.
  • the device 500 may also include or be in communication with a sound sensing device 522, such as a microphone or any other sound sensing device that can sense sound in the vicinity of the device 500, either existing or to be developed in the future.
  • the sound sensing device 522 may be placed to directly face the user who runs the apparatus 500, and may be used to receive sounds made by the user when the apparatus 500 is operated, such as voice or other utterances.
  • the processor 502 and the memory 504 of the device 500 are illustrated in FIG. 6 as being integrated in a single unit, other configurations may also be used.
  • the operation of the processor 502 may be distributed among multiple directly-coupled machines (each machine has one or more processors), or distributed in a local area or other network.
  • the memory 504 may be distributed among multiple machines, such as a network-based memory or a memory among multiple machines running the device 500. Although only a single bus is shown here, the bus 512 of the device 500 may be formed by multiple buses.
  • the slave memory 514 may be directly coupled to other components of the device 500 or may be accessed through a network, and may include a single integrated unit, such as one memory card, or multiple units, such as multiple memory cards. Therefore, the device 500 can be implemented in various configurations.
  • the color video in addition to the luminance (Y) component, the color video also contains chrominance components (U, V). Therefore, in addition to encoding the luma component, it is also necessary to encode the chroma component.
  • YUV4:4:4, YUV4:2:2, YUV4:2:0 there are generally YUV4:4:4, YUV4:2:2, YUV4:2:0.
  • the cross indicates the sampling point of the luminance component
  • the circle indicates the sampling point of the chrominance component.
  • 4:4:4 format indicates that the chroma component is not down-sampled
  • 4:2:2 format indicates that the chroma component is downsampled horizontally with respect to the luma component at 2:1, without vertical downsampling. For every two U sampling points or V sampling points, each row contains four Y sampling points;
  • 4:2:0 format indicates that the chroma component is downsampled horizontally with respect to the luma component at a ratio of 2:1, and vertically downsampled at a ratio of 2:1.
  • YUV4:2:0 is the most common.
  • the chroma component of the image block is also referred to as a chroma block or a chroma component block in this application.
  • This application is introduced in YUV4:2:0, but it can also be applied to other sampling methods of luma and chroma components.
  • pixels in a chroma image are simply referred to as chroma sampling points, or chroma points; pixels in a luma image (picture) are simply referred to as luma sampling points, or Brightness point.
  • chroma intra prediction Similar to the luma component, chroma intra prediction also uses the boundary pixels of the neighboring reconstructed blocks around the current chroma block as the reference pixels of the current block, and maps the reference pixels to the pixels in the current chroma block according to a certain prediction mode , As the predicted value of pixels in the current chroma block.
  • the difference is that since the texture of the chroma component is generally simple, the number of intra prediction modes of the chroma component is generally less than that of the luma component.
  • the cross-component prediction mode is also called the cross-component intra prediction mode, or CCLM prediction mode.
  • the CCLM prediction mode can also be referred to as the linear model mode.
  • the LM mode (referred to as a linear model, or linear mode for short) is a chroma intra prediction method that utilizes the texture correlation between luma and chroma. LM uses the reconstructed luminance component to derive the current chroma block prediction value according to a linear model, which can be expressed as:
  • Both ⁇ and ⁇ are linear model coefficients, ⁇ scaling factor, ⁇ is the offset factor, pred C (i,j) is the predicted value of the chroma pixels at (i,j), rec i L (i,j) The pixel value of the luminance reconstruction at the (i, j) position after downsampling to the resolution of the chroma component for the corresponding luminance reconstruction block of the current chroma block (hereinafter referred to as the corresponding luminance block).
  • the resolution of the luma component is 4 times the resolution of the chroma component (twice the width and height).
  • the luma component needs to be The downsampling method with the same chroma component is downsampled to chroma resolution before use.
  • the linear model coefficients do not need to be encoded and transmitted, but use the edge pixels of the neighboring reconstructed blocks of the current chroma block and the luminance pixels at corresponding positions of the edge pixels to derive ⁇ and ⁇ .
  • Figure 8 shows an embodiment of the cross-component prediction mode.
  • recL is the reconstructed luma block (the current chroma block corresponds to the luma block and adjacent reference pixels)
  • recL' is the down-sampled luma block
  • recC' is the neighboring reconstructed reference pixel of the current chroma block .
  • the size of the current chroma block is WxH, and the adjacent reconstructed pixels on the upper side and the left side are used as reference pixels.
  • the corresponding luma block size is 2Wx2H.
  • the luma block and the luma block reference pixels are downsampled to color Resolution, the pixel block shown in Figure 8(b) is obtained.
  • the adjacent reference pixels in FIG. 8(b) and FIG. 8(c) form a one-to-one correspondence.
  • the adjacent upper pixels and adjacent left pixels used for calculating the linear model coefficients are called adjacent pixels, the upper side is the adjacent upper pixels, and the left side is the adjacent left pixels.
  • the pixels adjacent to the chroma block are called adjacent pixels (including adjacent upper pixels and adjacent left pixels), and the pixels adjacent to the luminance block are called adjacent pixels (including adjacent upper pixels) And the adjacent left pixel).
  • the chroma pixels correspond to the luma pixels one-to-one, and the values of the sampling points constitute value pairs.
  • the luminance pixels generally need to be obtained through downsampling (because the resolution of the luminance component is different from the chrominance), which is expressed as Luma’ samples.
  • Chroma pixels Chroma samples are generally one or two rows of pixels adjacent to the upper side of the current chroma block, and one or two columns of pixels on the left.
  • FIG. 9 is a schematic diagram using one row and one column
  • FIG. 10 is a schematic diagram using two rows and two columns.
  • the LM mode can effectively utilize the correlation between the luma component and the chroma component. Compared with the directional prediction mode, the LM method is more flexible, thereby providing a more accurate prediction signal for the chroma component.
  • This application provides a method for predicting chroma blocks.
  • the processing flow shown in FIG. 11 will be described in detail in conjunction with a specific implementation manner. This process exists in both the encoding process and the decoding process.
  • the decoding end is used as an example to explain the scheme, and the content can be as follows:
  • Step 1101 Obtain the chromaticity value of the chromaticity pixel at the preset position from the adjacent pixels of the chromaticity block.
  • the chroma block is the chroma block to be intra-predicted.
  • the number of chroma pixels at a preset position (which may be simply referred to as a preset number) may be preset, for example, the preset number is 2, 4, 6, 8 and so on.
  • the neighboring pixels of the chroma block refer to the reconstructed pixels adjacent to the chroma block, see FIG. 9 and FIG. 10 above.
  • the preset position is generally (0, -1) (X-1,- 1), (-1, 0), (-1, Y-1), the chromaticity value of the chromaticity pixel at the preset position can be obtained from the adjacent pixels of the chromaticity block.
  • the decoding end may determine the intra prediction mode corresponding to the chroma block based on the indication information in the code stream, and determine the preset position according to the intra prediction mode.
  • the corresponding processing may be as follows:
  • Obtain indication information determine the intra prediction mode corresponding to the chroma block based on the indication information, and determine the preset position according to the intra prediction mode corresponding to the chroma block.
  • the intra prediction mode corresponding to the chroma block may include at least one of LM, LMA, and LML.
  • the indication information is used to indicate the intra prediction mode corresponding to the chroma block.
  • the intra prediction mode corresponding to the chroma block is encoded and then sent to the decoding side (this process will be described later).
  • the decoding end may obtain indication information in the received code stream, and determine the intra prediction mode corresponding to the chroma block based on the indication information.
  • the subsequent decoding end may determine the preset position according to the intra prediction mode corresponding to the chroma block.
  • the indication information can be set in the syntax table, as shown in Table 1:
  • the syntax element CuPredMode[x0][y0] in the syntax table is used to indicate whether the prediction mode of the current chroma block is an intra prediction mode or an inter prediction mode.
  • CuPredMode[x0][y0] is MODE_INTRA, indicating that the current chroma block uses intra prediction mode
  • CuPredMode[x0][y0] is MODE_INTER, indicating that the current chroma block uses inter prediction mode.
  • x0, y0 represent the coordinates of the current chroma block in the video image.
  • intra_chroma_pred_mode[x0][y0] is used to indicate the intra prediction mode information of the current chroma block (that is, the above-mentioned indication information).
  • LM0, LM1, ..., LM(N-1) represent different intra prediction modes.
  • step 1101 when there are multiple linear modes, there are different preset positions for different linear modes, and the corresponding processing of step 1101 may be as follows:
  • the chroma value of the chroma pixel at the preset position is obtained.
  • the intra prediction mode corresponding to the chroma block when decoding at the decoding end, the intra prediction mode corresponding to the chroma block may be determined, and then the correspondence between the preset intra prediction mode and the preset position may be obtained, and in the correspondence, determine The preset position corresponding to the intra prediction mode of the chroma block. Then, among the adjacent pixels of the chroma block, the chroma value of the chroma pixel at the preset position is obtained.
  • the recorded preset position may be the position coordinates of the preset position.
  • an embodiment of the present application establishes a plane rectangular coordinate corresponding to the chroma block, and takes the first chroma pixel in the upper left corner of the chroma block as the coordinate origin, Horizontally to the right is the positive direction of the x-axis, and vertically downward is the positive direction of the y-axis.
  • the position coordinates of the adjacent upper pixels of the chroma block are (0, -1), (1, -1), ..., (X-1, -1), the adjacent left pixels of the chroma block
  • the position coordinates are (-1, 0), (-1, 1), ..., (-1, Y-1)
  • X represents the width of the chroma block (that is, the number of pixels in the width direction of the chroma block)
  • Y represents the height of the chroma block (that is, the number of pixels in the height direction of the chroma block).
  • the position coordinates of the preset position may be (0, -1) (X-1, -1) (-1,0) (-1, Y-1) .
  • the position coordinates of the preset position may be (0, -1) (X/4, -1) (X-1-X/4, -1) (X -1, -1).
  • the position coordinates of the preset position may be (-1,0)(-1, Y/4)(-1,Y-1-Y/4)(- 1, Y-1).
  • the position coordinates of the preset position may be (X-2, -1) (X-1, -1) (-1, Y-2) (-1, Y-1).
  • the position coordinates of the preset position may be (0, -1) (1, -1) (X-2, -1) (X- 1, -1).
  • the linear mode is LM, LMA and LML
  • the position coordinates of the preset positions are also listed separately, which can be as follows:
  • the position coordinates of the preset position may be (0, -1) (X-1, -1), (-1, 0), (-1, Y- 1), see the shaded circles in Fig. 13.
  • the position coordinates of the preset position may be (0, -1), (X/4, -1), (X-1-X/4, -1) , (X-1, -1), see the shaded circle in (a) of Figure 14, or (0, -1) (X/4, -1) (3*X/4, -1) (X-1, -1), see the shaded circles in (b) of Figure 14.
  • the position coordinates of the preset position may be (-1, 0) (-1, Y/4) (-1, Y-1-Y/4) (- 1, Y-1), see the shaded circles in (a) of Figure 15, or (-1, 0) (-1, Y/4) (-1, 3*Y/4) (-1 , Y-1), see the shaded circles in (b) of Figure 15.
  • the preset number may be 2, and the position coordinates of the preset position may be (X-1, -1) and (-1, Y-1), as shown in FIG. 16
  • the circles shaded with diagonal lines in (a) can also be (X/2, -1) and (-1, Y/2). See the circles shaded with diagonal lines in (b) of Figure 16 or (X/2, -1) and (-1, Y-1), see the shaded circles in (c) of Figure 16, can also be (X-1, -1) and (-1, Y /2), see the shaded circles in (d) of Figure 16.
  • X and Y are generally greater than or equal to 4, and in the above FIGS. 13 and 16, X takes 8 and Y takes 8, the above FIG. 14 (a) X takes 8, and FIG. 14 (b) X takes 16; (a) Y in FIG. 15 takes 8; and (b) Y in FIG. 15 takes 16.
  • the above values are only one possible implementation manner, and the embodiments of the present application are not limited.
  • the boxes represent chroma blocks.
  • Step 1102 Based on the adjacent pixels of the luminance block corresponding to the chroma block, obtain the luminance value of the luminance pixel corresponding to the chroma pixel at the preset position.
  • step 1102 there may be multiple ways to select the brightness value.
  • Manner 1 In the adjacent pixels of the luma block, the position coordinates of the luma pixel corresponding to the chroma pixel at the i-th preset position in the preset position are determined as (2*X i , 2*Y i ), where The position coordinates of the chroma pixels at the i preset positions are (X i , Y i ). According to the position coordinates of the brightness pixels corresponding to the chroma pixels at the preset positions, from the neighboring pixels of the brightness block corresponding to the chroma block To obtain the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position.
  • the i-th preset position is any preset position among the preset positions.
  • the position coordinates of the chroma pixel at the i-th preset position in the preset position are (X i , Y i ) (X i is the i-th preset (The abscissa of the position in the coordinate system shown in FIG. 12, Y i is the ordinate of the i-th preset position in the coordinate system shown in FIG. 12), and the i The position coordinates of the luminance pixel corresponding to the chroma pixels at the preset positions are (2*X i , 2*Y i ). In this way, the position coordinates of the luminance pixel corresponding to the chroma pixel at the preset position can be obtained. Then, the position coordinates of the brightness pixel corresponding to the chroma pixel at the preset position can be used to obtain the brightness value from the corresponding brightness pixel.
  • Method 2 According to the position coordinates of the jth preset position in the preset position, determine the position coordinates of multiple sampling points corresponding to the jth preset position in the adjacent pixels of the brightness block; The position coordinates determine the position coordinates of the luminance pixel corresponding to the chroma pixel at the jth preset position; according to the position coordinates of the brightness pixel corresponding to the chroma pixel at the preset position, from the neighboring pixels of the brightness block corresponding to the chroma block In the method, the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position is obtained.
  • the j-th preset position is any preset position among the preset positions.
  • the position coordinates of the chroma pixel at the j-th preset position in the preset position are (X j , Y j ) (X j is the j-th preset
  • X j is the j-th preset
  • Y j is the ordinate of the j-th preset position in the coordinate system shown in FIG.
  • a weighted method can be used, and the position coordinates of multiple sampling points can be: (2*Xj,2*Yj), (2*Xj,2*Yj+1), (2*Xj+1,2* Yj), (2*Xj+1,2*Yj+1), (2*Xj+2,2*Yj), (2*Xj+2,2*Yj+1), corresponding to the position of each sampling point
  • a weight which is 2/8, 1/8, 1/8, 2/8, 1/8, 1/8, 1/8, after weighting, you can get the corresponding chroma pixel at the jth preset position
  • the position coordinates of the luminance pixels are (2*Xj, 2*Yj+0.5).
  • the weighting method may not be used, and the embodiments of the present application are not limited.
  • the position coordinates of the luminance pixel corresponding to the chroma pixel at the preset position can be obtained.
  • the position coordinates of the brightness pixel corresponding to the chroma pixel at the preset position can be used to obtain the brightness value from the corresponding brightness pixel.
  • step 1103 the obtained brightness value is divided into a first brightness set and a second brightness set.
  • the obtained brightness value may be divided into a first brightness set and a second brightness set.
  • Method 1 Determine the average value of the brightness values of the brightness pixels corresponding to the chroma pixels at the preset position.
  • the luminance values corresponding to the luminance pixels corresponding to the chromaticity pixels at the preset position are less than or equal to the average of the luminance values to form a first luminance set, and the luminance values corresponding to the luminance pixels corresponding to the chromaticity pixel at the preset position are greater than
  • the average brightness value constitutes a second brightness set.
  • the average value of the brightness values obtained in step 1102 may be determined, and then the brightness values obtained in step 1102 that have a brightness value less than or equal to the average value of the brightness values may be determined, and these brightness values may be combined into a first brightness Set, and it can be determined that the brightness value obtained in step 1102 is greater than the average of the brightness values, and these brightness values are grouped into a second brightness set, so that the brightness value in the first brightness set is less than the second brightness set Brightness value.
  • the average brightness value is:
  • Method 2 Arrange the brightness values of the brightness pixels corresponding to the chroma pixels at the preset position in ascending order to obtain the first brightness value queue; if the number of brightness pixels in the first brightness value queue is an even number, Then, the brightness values of the first half of the first brightness value queue are combined into a first brightness set, and the brightness values of the second half of the brightness value queue are combined into a second brightness set.
  • the brightness values obtained in step 1102 may be arranged in ascending order to obtain a first brightness value queue. If the number of brightness pixels in the first brightness value queue is an even number, you can The brightness values of the first half of the first brightness value queue are determined, these brightness values are combined into a first brightness set, and the brightness values of the second half of the first brightness value queue are determined, and these brightness values are combined into a second brightness set.
  • step 1102 there are 4 brightness values obtained in step 1102, which are L1, L2, L3, L4 in sequence, and the size relationship between them is L4 ⁇ L2 ⁇ L1 ⁇ L3, then the first brightness value queue is L4, L2, L1, L3, then the first brightness set is ⁇ L4, L2 ⁇ , and the second brightness set is ⁇ L1, L3 ⁇ .
  • Method 3 Arrange the brightness values of the brightness pixels corresponding to the chroma pixels at the preset position in descending order to obtain the second brightness value queue; if the number of brightness pixels in the second brightness value queue is an even number Then, the brightness values in the second half of the second brightness value queue form the first brightness set, and the brightness values in the first half of the brightness value queue form the second brightness set.
  • the brightness values obtained in step 1102 may be arranged in descending order to obtain a second brightness value queue. If the number of brightness pixels in the second brightness value queue is an even number, then The brightness values of the second half of the second brightness value queue may be determined, and these brightness values are combined into a first brightness set, and the brightness values of the first half of the second brightness value queue may be determined, and these brightness values are combined into a second brightness set.
  • step 1102 there are 4 brightness values obtained in step 1102, which are L1, L2, L3, L4 in sequence, and the size relationship between them is L3>L1>L2>L4, then the second brightness value queue is L3, L1, L2, L4, then the first brightness set is ⁇ L4, L2 ⁇ , and the second brightness set is ⁇ L1, L3 ⁇ .
  • the first (N-1)/2 brightness values may constitute the first Brightness set, the last (N+1)/2 brightness values make up the second brightness set, or the first (N+1)/2 brightness values make up the first brightness set, and the latter (N-1)/2
  • the brightness value constitutes the second brightness set.
  • the first (N-1)/2 brightness values can be used to form the second Brightness set, the last (N+1)/2 brightness values make up the first brightness set, similarly, the first (N+1)/2 brightness values make up the second brightness set, and the latter (N-1)/2
  • the brightness values constitute the first brightness set.
  • Step 1104 the chromaticity values of the chromaticity pixels corresponding to the luminance pixels to which the luminance values in the first luminance set belong are formed into the first chromaticity set, and the color corresponding to the luminance pixels to which the luminance values in the second luminance set belong The chromaticity values of the pixels form a second chromaticity set.
  • the chromaticity values corresponding to all the brightness values in the first brightness set may be combined into a first chromaticity set, and the second brightness set
  • the chromaticity values corresponding to all luminance values form a second chromaticity set. It can be expressed as:
  • step 1101 when determining the luminance value, the luminance pixel corresponding to the chromaticity pixel is used, where the chromaticity value corresponding to the luminance value refers to the color of the chromaticity pixel corresponding to the luminance pixel to which the luminance value belongs Degree value.
  • Step 1105 Determine the color according to the average of the luminance values in the first luminance set, the average of the luminance values in the second luminance set, the average of the chromaticity values in the first chromaticity set, and the average of the chromaticity values in the second chromaticity set The scaling factor in the linear model corresponding to the degree block.
  • the mean value of the brightness values in the first brightness set and the second brightness set may be determined.
  • the average of the luminance values, and determine the average of the chromaticity values in the first chromaticity set and the average of the chromaticity values in the second chromaticity set Corresponding to the above method 1, it is expressed as:
  • a formula can be used to determine the scaling factor, and the corresponding processing can be as follows:
  • C Lmean is the average of the chroma values in the first chroma set
  • C Rmean is the average of the chroma values in the second chroma set
  • L Lmean is the first The average value of the luminance values in a luminance set
  • L Rmean is the average value of the luminance values in the second luminance set.
  • a preset calculation formula of the scaling factor can be obtained, and then C Lmean , C Rmean , L Lmean and L Rmean are substituted into the calculation formula of the scaling factor , The scaling factor in the linear model corresponding to the chroma block is obtained.
  • Step 1106 Determine the offset factor in the linear model corresponding to the chroma block according to the scaling factor.
  • the offset factor in the linear model corresponding to the chroma block may be determined according to the scaling factor.
  • the offset factor there are various processing methods. There are two possible ways:
  • Method 1 Determine the offset factor corresponding to the chroma block according to the scaling factor, the average of the chroma values in the first chroma set, and the average of the luma values in the first luma set.
  • the average value of the chromaticity values in the first chromaticity set may be determined: And the average value of the brightness values in the first brightness set can be determined:
  • the scaling factor, the average value of the chromaticity values in the first chromaticity set and the average value of the luminance values in the first luminance set are used to determine the offset factor corresponding to the chromaticity block.
  • ⁇ C Lmean - ⁇ *L Lmean , where ⁇ is the scaling factor, ⁇ is the offset factor in the linear model corresponding to the chroma block, C Lmean is the average of the chroma values in the first chroma set, and L Lmean is The average of the brightness values in the first brightness set.
  • Method 2 Determine the offset factor in the linear model corresponding to the chroma block according to the scaling factor, the average of the chroma values of the chroma pixels at the preset position, and the average of the luminance values of the luminance pixels corresponding to the chroma pixels.
  • the average value of the chromaticity values of the chromaticity pixels at the preset position may be determined: And the average value of the brightness values of the brightness pixels corresponding to the chroma pixels can be determined:
  • ⁇ C mean - ⁇ *L mean , where ⁇ is the scaling factor, ⁇ is the offset factor in the linear model corresponding to the chroma block, C mean is the average of the chroma values of the chroma pixels at the preset position, L mean is the average of the brightness values of the brightness pixels corresponding to the chroma pixels at the preset position.
  • Step 1107 Determine the prediction information of the chroma block according to the scaling factor, the offset factor, and the luminance reconstruction information corresponding to the chroma block.
  • the luminance reconstruction information corresponding to the chroma block includes down-sampling information of the luminance reconstruction block corresponding to the chroma block.
  • the brightness reconstruction information, the scaling factor, and the offset factor corresponding to the chroma block may be used to obtain the prediction information of the chroma block.
  • the method of determining the intra prediction mode is different.
  • each intra frame will be used.
  • the prediction mode encodes the chroma block, and then uses the rate-distortion optimization (RDO) criterion to determine the intra-frame prediction mode with the best coding effect, writes it into the above-mentioned syntax table, and adds to In the code stream, in this way, the decoding end can directly determine which intra prediction mode to use for decoding from the code stream.
  • RDO rate-distortion optimization
  • the method for determining the intra prediction mode may be as follows:
  • Step 1101 to step 1107 are used to determine the prediction information of the chroma block, the original information of the chroma block is subtracted from the prediction information to obtain residual information, and then the residual information is transformed to obtain a transform coefficient, and the transform coefficient is quantized After processing, quantized coefficients are obtained, and entropy coding is performed on the quantized coefficients to obtain a code stream.
  • the aforementioned encoding end may be an encoding end using H.263, H.264, MPEG-2, MPEG-4, VP8, VP9, and the corresponding decoding end may also be using H.263, H .264, MPEG-2, MPEG-4, VP8, VP9 decoder.
  • embodiments of the present application only take adjacent rows of pixels as an example, and the embodiments of the present application can also be applied to the scene of two adjacent rows of pixels shown in FIG. The same, but the position coordinates of the preset number of position points are different.
  • the chromaticity value of the chromaticity pixel at the preset position may be obtained from the adjacent pixels of the chromaticity block, and then from the adjacent pixels of the luminance block corresponding to the chromaticity block , Obtain the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position, divide the obtained brightness value into the first brightness set and the second brightness set, and then divide the corresponding chroma value based on the brightness value grouping There are two sets, namely the first chroma set and the second chroma set.
  • the chromaticity can then be determined according to the average of the luminance values in the first luminance set, the average of the luminance values in the second luminance set, the average of the chromaticity values in the first chromaticity set, and the average of the chromaticity values in the second chromaticity set
  • the scaling factor in the linear model corresponding to the block After determining the scaling factor, you can use the scaling factor to determine the offset factor in the linear model corresponding to the chroma block. Finally, use the scaling factor, the offset factor, and the brightness corresponding to the chroma block. Reconstruct the information and determine the prediction information of the chroma block.
  • a preset number of chrominance values and a preset number of luminance values are selected, and then divided into two luminance sets and two chrominance sets, based on the average value and each color of the luminance values in each luminance set
  • the average of the chroma values in the degree set determines the scaling factor of the brightness block, and then determines the offset factor, and does not use a lot of multiplication, so it can save encoding time and decoding time.
  • FIG. 17 is a structural diagram of a chroma block prediction apparatus provided by an embodiment of the present application.
  • the device can be implemented as part or all of the device through software, hardware, or a combination of both.
  • An apparatus provided by an embodiment of the present application can implement the processes described in FIGS. 11 to 16 of the embodiment of the present application.
  • the apparatus includes: an obtaining module 1710, a dividing module 1720, and a determining module 1730, where:
  • the obtaining module 1710 is configured to obtain the chromaticity value of the chromaticity pixel at the preset position from the adjacent pixels of the chromaticity block; based on the adjacent pixel of the luminance block corresponding to the chromaticity block, obtain the preset position
  • the luminance value of the luminance pixel corresponding to the chroma pixel can be specifically used to realize the above-mentioned acquisition function of FIG. 11 and the implicit steps involved;
  • the dividing module 1720 is configured to divide the obtained luminance value into a first luminance set and a second luminance set; the chromaticity value of the chromaticity pixel corresponding to the luminance pixel to which the luminance value in the first luminance set belongs is composed The first chromaticity set, and the chromaticity values of the chromaticity pixels corresponding to the luminance pixels to which the luminance values in the second luminance set belong to form a second chromaticity set, which can be specifically used to implement the above-mentioned division function of FIG. , And the hidden steps involved;
  • the determining module 1730 is configured to determine the average value of luminance values in the first luminance set, the average value of luminance values in the second luminance set, the average value of chromaticity values in the first chromaticity set, and the second color
  • the average value of the chroma values in the chroma set determines the scaling factor in the linear model corresponding to the chroma block; according to the scaling factor, determines the offset factor in the linear model corresponding to the chroma block;
  • the scaling factor, the offset factor, and the luminance reconstruction information corresponding to the chroma block to determine the prediction information of the chroma block, wherein the luminance reconstruction information corresponding to the chroma block includes the correspondence of the chroma block
  • the down-sampling information of the luminance reconstruction block of can be used to implement the above-mentioned determination function of FIG. 11 and the implicit steps involved.
  • the obtaining module 1710 is also used to:
  • the intra prediction mode includes at least one of a linear mode LM, an upper linear mode LMA, and a left linear mode LML;
  • the preset position is determined according to the intra prediction mode corresponding to the chroma block.
  • the obtaining module 1710 is used to:
  • the intra prediction mode corresponding to the chroma block obtains the chroma pixels of the preset position Chroma value.
  • the position coordinates of adjacent upper pixels of the chroma block are (0, -1), (1, -1), ..., (X-1, -1) and the chroma block
  • the position coordinates of the adjacent left pixel are (-1, 0), (-1, 1), ..., (-1, Y-1);
  • the intra prediction mode corresponding to the chroma block is a cross-component linear mode LM
  • the position coordinates of the chroma pixel at the preset position are (0, -1) (X-1, -1), (- 1, 0), (-1, Y-1).
  • the position coordinates of adjacent upper pixels of the chroma block are (0, -1), (1, -1), ..., (X-1, -1);
  • the position coordinates of the preset position are (0, -1), (X/4, -1), (X- 1-X/4, -1), (X-1, -1), or (0, -1) (X/4, -1) (3*X/4, -1) (X-1,- 1).
  • the position coordinates of adjacent left pixels of the chroma block are (-1, 0), (-1, 1), ..., (-1, Y-1);
  • the position coordinates of the preset position are (-1, 0) (-1, Y/4) (-1, Y -1-Y/4)(-1,Y-1), or (-1,0)(-1,Y/4)(-1,3*Y/4)(-1,Y-1).
  • the obtaining module 1710 is used to:
  • the position coordinate of the luminance pixel corresponding to the chroma pixel at the i-th preset position in the preset position is (2*X i , 2*Y i ), where,
  • the position coordinates of the chromaticity pixel at the i-th preset position are (X i , Y i ), and according to the position coordinates of the luminance pixel corresponding to the chromaticity pixel at the preset position, from the corresponding Obtaining the luminance value of the luminance pixel corresponding to the chroma pixel at the preset position from the adjacent pixels of the luminance block; or,
  • the position coordinates of the jth preset position in the preset position in adjacent pixels of the brightness block, determine the position coordinates of a plurality of sampling points corresponding to the jth preset position; according to the Position coordinates of a plurality of sampling points, determining the position coordinates of the luminance pixel corresponding to the chroma pixel at the jth preset position; according to the position coordinates of the brightness pixel corresponding to the chroma pixel at the preset position, from the In the adjacent pixels of the luminance block corresponding to the chroma block, the luminance value of the luminance pixel corresponding to the chroma pixel at the preset position is obtained.
  • the dividing module 1720 is used to:
  • the brightness values corresponding to the chrominance pixels at the preset position are less than or equal to the average of the brightness values to form a first brightness set, and the brightness corresponding to the chroma pixels at the preset position is formed Among the brightness values of the pixels, brightness values greater than the average of the brightness values form a second brightness set.
  • the dividing module 1720 is used to:
  • the determination module 1730 is used to:
  • ⁇ is the scaling factor in the linear model corresponding to the chroma block
  • C Lmean is the average of the chroma values in the first chroma set
  • C Rmean is the chroma values in the second chroma set Mean value
  • L Lmean is the mean value of the brightness values in the first brightness set
  • L Rmean is the mean value of the brightness values in the second brightness set.
  • the determination module 1730 is used to:
  • the offset factor in the linear model corresponding to the chroma block is determined according to the scaling factor, the average of the chroma values in the first chroma set, and the average of the luma values in the first luma set.
  • the determination module 1730 is used to:
  • ⁇ C Lmean - ⁇ *L Lmean , where ⁇ is the scaling factor, ⁇ is the offset factor in the linear model corresponding to the chroma block, and C Lmean is the color in the first chroma set
  • the average of the degree values, L Lmean is the average of the brightness values in the first brightness set.
  • the determination module 1730 is used to:
  • the determination module 1730 is used to:
  • ⁇ C mean - ⁇ *L mean , where ⁇ is the scaling factor, ⁇ is the offset factor in the linear model corresponding to the chroma block, and C mean is the chroma pixel at the preset position
  • the average of the chromaticity values of, L mean is the average of the luminance values of the luminance pixels corresponding to the chromaticity pixels at the preset position.
  • the chromaticity value of the chromaticity pixel at the preset position may be obtained from the adjacent pixels of the chromaticity block, and then from the adjacent pixels of the luminance block corresponding to the chromaticity block , Obtain the brightness value of the brightness pixel corresponding to the chroma pixel at the preset position, divide the obtained brightness value into the first brightness set and the second brightness set, and then divide the corresponding chroma value based on the brightness value grouping There are two sets, namely the first chroma set and the second chroma set.
  • the chromaticity can then be determined according to the average of the luminance values in the first luminance set, the average of the luminance values in the second luminance set, the average of the chromaticity values in the first chromaticity set, and the average of the chromaticity values in the second chromaticity set
  • the scaling factor in the linear model corresponding to the block After determining the scaling factor, you can use the scaling factor to determine the offset factor in the linear model corresponding to the chroma block. Finally, use the scaling factor, the offset factor, and the brightness corresponding to the chroma block. Reconstruct the information and determine the prediction information of the chroma block.
  • a preset number of chrominance values and a preset number of luminance values are selected, and then divided into two luminance sets and two chrominance sets, based on the average value and each color of the luminance values in each luminance set
  • the average of the chroma values in the degree set determines the scaling factor of the brightness block, and then determines the offset factor, and does not use a lot of multiplication, so it can save encoding time and decoding time.
  • the prediction device of the chroma block provided in the above embodiment is only exemplified by the division of the above functional modules.
  • the above functions can be allocated according to needs Completed by different functional modules, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above.
  • the chroma block prediction apparatus and the chroma block prediction method embodiments provided in the above embodiments belong to the same concept. For the specific implementation process, see the method embodiments, and details are not described here.
  • the present application also provides a computer-readable storage medium that stores instructions, and when the computer-readable storage medium runs on a computing device, causes the computing device to execute the method of prediction.
  • the present application also provides a computer program product containing instructions, which, when the computer program product runs on a computing device, causes the computing device to perform the above-described chroma block prediction method.
  • the above embodiments it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof, and when implemented in software, it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a server or a terminal, all or part of the processes or functions described in the embodiments of the present application are generated.
  • the computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be from a website site, computer, server or data center Transmission to another website, computer, server or data center via wired (such as coaxial cable, optical fiber, digital subscriber line) or wireless (such as infrared, wireless, microwave, etc.).
  • the computer-readable storage medium may be any available medium that can be accessed by a server or a terminal, or a data storage device such as a server, a data center, or the like that includes one or more available medium integrations.
  • the usable medium may be a magnetic medium (such as a floppy disk, a hard disk, a magnetic tape, etc.), an optical medium (such as a Digital Video Disk (DVD), etc.), or a semiconductor medium (such as a solid-state hard disk, etc.).
  • a magnetic medium such as a floppy disk, a hard disk, a magnetic tape, etc.
  • an optical medium such as a Digital Video Disk (DVD), etc.
  • DVD Digital Video Disk
  • semiconductor medium such as a solid-state hard disk, etc.

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Abstract

本申请提供了一种色度块的预测方法和装置，属于视频编解码技术领域。所述方法包括：从色度块的相邻像素中，获取预设位置的色度像素的色度值，基于色度块对应的亮度块的相邻像素，获取上述色度像素对应的亮度像素的亮度值，将亮度值分为第一亮度集合和第二亮度集合，相应的，将色度值分为第一色度集合和第二色度集合。根据第一亮度集合中亮度值的均值、第二亮度集合中亮度值的均值、第一色度集合中色度值的均值和第二色度集合中色度值的均值，确定线性模型中的缩放系数，使用缩放系数确定色度块对应的偏移因子，使用缩放系数、偏移因子和色度块对应的亮度重建信息，确定色度块的预测信息。这样，可以提高色度块的预测效率。

Description

色度块的预测方法和装置
本申请要求于2019年01月03日提交的申请号为201910005667.3、发明名称为“色度块的预测方法和装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及视频编解码技术领域，特别涉及一种色度块的预测方法和装置。
背景技术
随着互联网技术的发展，视频应用程序越来越多，视频应用程序中对高清视频的需求越来越多，然而由于高清视频的数据量比较大，如果想要高清视频在有限的网络带宽中传输，需要对高清视频进行编码处理。一般编码处理主要包括帧内预测、帧间预测、变换、量化、熵编码、环内滤波等环节。
相关技术中，在进行帧内预测时，对于任一色度块，可以采用跨分量线性模式(Cross Component Linear Mode，CCLM)(也可以称为跨分量预测模式(Cross-Component Predition，CCP)，还可以称为是(Cross-Component Intra Predition，CCIP)，还可以简称为线性模式(linear mode，LM))，确定预测信息，这是一种利用亮度和色度之间的相关性的色度帧内预测方法，它使用已重建亮度分量按照线性模型导出当前色度块预测信息，可以表示为如下式子：pred C(i,j)＝α*rec i L(i,j)+β，α和β为帧内预测模型参数，α为缩放系数，β为偏移因子，pred C(i,j)为(i,j)位置上的色度像素的预测值，rec i L(i,j)为当前色度块对应亮度重建块下采样至色度分量分辨率后(i,j)位置上的亮度重建像素值。缩放系数和偏移因子并不需要编码传输，而是使用当前色度块的相邻已重建块的边缘像素以及边缘像素对应位置的亮度像素导出，方法可以为
Figure PCTCN2019124399-appb-000001
其中，N为相邻已重建块的边缘像素的数目，L(n)为第n个亮度像素，C(n)为第n个色度像素。
这样，每个使用CCLM的色度块，均需要确定缩放系数和偏移因子，然而上述确定过程中有大量的乘法，复杂度较高，从而导致色度块的预测效率比较低。
发明内容
为了解决相关技术的问题，本申请实施例提供了一种色度块的预测方法和装置。所述技术方案如下：
第一方面，提供了一种色度块的预测方法，所述方法包括：
从色度块的相邻像素中，获取预设位置的色度像素的色度值。基于所述色度块对应的亮 度块的相邻像素，获取所述预设位置的色度像素对应的亮度像素的亮度值。将获取到的亮度值分为第一亮度集合和第二亮度集合。将所述第一亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第一色度集合，并将所述第二亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第二色度集合。根据所述第一亮度集合中亮度值的均值、所述第二亮度集合中亮度值的均值、所述第一色度集合中色度值的均值和所述第二色度集合中色度值的均值，确定所述色度块对应的线性模型中的缩放系数。根据所述缩放系数，确定所述色度块对应的所述线性模型中的偏移因子。根据所述缩放系数、所述偏移因子和所述色度块对应的亮度重建信息，确定所述色度块的预测信息。
本申请实施例所示的方案，在对当前色度块(后续可以简称为色度块)进行帧内预测时，可以从色度块的相邻像素中，获取预设位置的色度像素的色度值。然后可以确定色度块对应的亮度块，基于亮度块的相邻像素，获取预设位置的色度像素对应的亮度像素的亮度值。将获取到的亮度值分为第一亮度集合和第二亮度集合。按照亮度值，色度值自动分成第一色度集合和第二色度集合。然后使用第一亮度集合中亮度值的均值、第二亮度集合中亮度值的均值、第一色度集合中色度值的均值和第二色度集合中色度值的均值，确定色度块对应的线性模型中的缩放系数。然后使用缩放系数确定色度块对应的线性模型中的偏移因子，最后使用色度块对应的亮度重建信息、缩放系数和偏移因子，得到色度块的预测信息，色度块对应的亮度重建信息包括色度块对应的亮度重建块的下采样信息。
这样，由于并未涉及到大量的乘法，所以可以减少计算量，进而可以提高色度块的预测效率。
在一种可能的实施方式中，所述基于色度块的相邻像素，获取预设位置的色度像素的色度值，包括：获取指示信息，基于指示信息确定所述色度块对应的帧内预测模式，其中，所述帧内预测模式包括线性模式LM、上侧线性模式(linear mode above，LMA)和左侧线性模式(linear mode left，LML)至少之一，根据所述色度块对应的帧内预测模式，确定所述预设位置。
本申请实施例所示的方案，在编码端进行编码时，可以将指示信息编码至码流中，然后发送至解码端。解码端可以在接收到的码流中，获取指示信息，基于该指示信息确定色度块对应的帧内预测模式。然后基于色度块对应的帧内预测模式，确定出预设位置。这样，可以使解码端确定出色度块所使用的帧内预测模式，然后基于帧内预测模式，确定预设位置。
在一种可能的实施方式中，所述从色度块的相邻像素中，获取预设位置的色度像素的色度值，包括：根据预设的帧内预测模式和预设位置的对应关系，以及色度块对应的帧内预测模式，在所述色度块的相邻像素中，获取所述预设位置的色度像素的色度值。
本申请实施例所示的方案，在解码端进行解码时，可以获取预设的帧内预测模式和位置的对应关系，在该对应关系中，确定该色度块的帧内预测模式对应的预设位置。然后使用该预设位置，在色度块的相邻像素中，获取预设位置的色度像素的色度值。
这样，可以对应不同的帧内预测模式，选取不同的预设位置，可以使色度块的预测结果更准确。
在一种可能的实施方式中，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)和所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，其中，X表示所述色度块的宽度，Y表示所述色度块的高度。如果所述色度块 对应的帧内预测模式为跨分量线性模式LM，则所述预设位置的色度像素的位置坐标为(0，-1)(X-1，-1)、(-1，0)、(-1，Y-1)。
本申请实施例所示的方案，对应色度块建立一个平面直角坐标，以色度块的左上角的第一个色度像素为坐标原点，水平向右为x轴的正方向，竖直向下为y轴的正方向。这样，色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)，色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，X表示色度块的宽度(即色度块的宽度方向上像素的数目)，Y表示色度块的高度(即色度块的高度方向上像素的数目)。帧内预测模式为LM时，预设位置的色度像素的位置坐标为(0，-1)(X-1，-1)、(-1，0)、(-1，Y-1)。
在一种可能的实施方式中，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)，其中，X表示所述色度块的宽度。如果所述色度块对应的帧内预测模式为跨分量上侧线性模式LMA，则所述预设位置的位置坐标为(0，-1)、(X/4，-1)、(X-1-X/4，-1)、(X-1，-1)，或者(0，-1)(X/4，-1)(3*X/4，-1)(X-1，-1)。
本申请实施例所示的方案，对应色度块建立一个平面直角坐标，以色度块的左上角的第一个色度像素为坐标原点，水平向右为x轴的正方向，竖直向下为y轴的正方向。帧内预测模式为LMA时，预设位置的位置坐标为(0，-1)、(X/4，-1)、(X-1-X/4，-1)、(X-1，-1)，或者(0，-1)(X/4，-1)(3*X/4，-1)(X-1，-1)，X表示色度块的宽度(即色度块的宽度方向上像素的数目)。
在一种可能的实施方式中，所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，其中，Y表示所述色度块的高度。如果所述色度块对应的帧内预测模式为跨分量左侧线性模式LML，则所述预设位置的位置坐标为(-1，0)(-1，Y/4)(-1，Y-1-Y/4)(-1，Y-1)，或者(-1，0)(-1，Y/4)(-1，3*Y/4)(-1，Y-1)。
本申请实施例所示的方案，对应色度块建立一个平面直角坐标，以色度块的左上角的第一个色度像素为坐标原点，水平向右为x轴的正方向，竖直向下为y轴的正方向。帧内预测模式为LML时，预设位置的位置坐标为(-1，0)(-1，Y/4)(-1，Y-1-Y/4)(-1，Y-1)，或者(-1，0)(-1，Y/4)(-1，3*Y/4)(-1，Y-1)，Y表示色度块的高度(即色度块的高度方向上像素的数目)。
在一种可能的实施方式中，所述从所述色度块对应的亮度块的相邻像素中，获取所述预设位置的色度像素对应的亮度像素的亮度值，包括：在所述亮度块的相邻像素中，确定所述预设位置中第i个预设位置的色度像素对应的亮度像素的位置坐标为(2*X i，2*Y i)，其中，所述第i个预设位置的色度像素的位置坐标为(X i，Y i)，根据所述预设位置的色度像素对应的亮度像素的位置坐标，从所述色度块对应的亮度块的相邻像素中，获取所述预设位置的色度像素对应的亮度像素的亮度值；或者，根据所述预设位置中第j个预设位置的位置坐标，在所述亮度块的相邻像素中，确定所述第j个预设位置对应的多个采样点的位置坐标；根据所述多个采样点的位置坐标，确定所述第j个预设位置的色度像素对应的亮度像素的位置坐标；根据所述预设位置的色度像素对应的亮度像素的位置坐标，从所述色度块对应的亮度块的相邻像素中，获取所述预设位置的色度像素对应的亮度像素的亮度值。
本申请实施例所示的方案，在对色度块进行解码时，预设位置中第i个预设位置的色度像素的位置坐标为(X i，Y i)，可以在亮度块的相邻像素中，确定第i个预设位置的色度像素 对应的亮度像素的位置坐标为(2*X i，2*Y i)。这样，可以得到预设位置的色度像素对应的亮度像素的位置坐标。
或者，在对色度块进行解码时，预设位置的中第j个预设位置的色度像素的位置坐标为(X j，Y j)，对于第j个预设位置的色度像素，确定(X j，Y j)对应到亮度块的相邻像素的多个采样点位置，然后基于这多个采样点位置的位置坐标，得到第j个预设位置的色度像素对应的亮度像素的位置坐标。例如，可以使用加权的方式，多个采样点位置的位置坐标可以为：(2*Xj,2*Yj)，(2*Xj,2*Yj+1)，(2*Xj+1,2*Yj)，(2*Xj+1,2*Yj+1)，(2*Xj+2,2*Yj)，(2*Xj+2,2*Yj+1)，对应每个采样点位置均有一个权值，分别为2/8、1/8、1/8、2/8、1/8、1/8，进行加权之后，即可得到第j个预设位置的色度像素对应的亮度像素的位置坐标为(2*Xj,2*Yj+0.5)。另外，也可以不采用加权方式，本申请实施例不做限定。这样，可以得到预设位置的色度像素对应的亮度像素的位置坐标。然后可以使用预设位置的色度像素对应的亮度像素的位置坐标，从相应的亮度像素，获取亮度值。
这样，可以更快速的确定出亮度值。
在一种可能的实施方式中，在接收到的码流中，获取指示信息。
本申请实施例所示的方案，在编码端进行编码时，可以将指示帧内预测模式的指示信息编码至码流中，然后发送至解码端。解码端可以在接收到的码流中，获取指示信息。
这样，可以使解码端确定出色度块所使用的帧内预测模式。
在一种可能的实施方式中，所述将获取到的亮度值划为第一亮度集合和第二亮度集合，包括：确定所述预设位置的色度像素对应的亮度像素的亮度值的均值。将所述预设位置的色度像素对应的亮度像素的亮度值中小于或等于所述亮度值的均值的亮度值组成第一亮度集合，并将所述预设位置的色度像素对应的亮度像素的亮度值中大于所述亮度值的均值的亮度值组成第二亮度集合。
本申请实施例所示的方案，确定获取到的所有亮度值中亮度值小于或等于亮度值的均值的亮度值，将这些亮度值组成第一亮度集合，并且可以确定获取到的所有亮度值中亮度值大于亮度值的均值的亮度值，将这些亮度值组成第二亮度集合，这样，第一亮度集合中的亮度值小于第二亮度集合中的亮度值。
这样，可以在不降低编码性能的情况下，提升色度块的预测速度。
在一种可能的实施方式中，所述将获取到的亮度像素分为第一亮度集合和第二亮度集合，包括：将所述预设位置的色度像素对应的亮度像素的亮度值按照从小到大的顺序进行排列，得到第一亮度值队列；如果所述第一亮度值队列中的亮度像素的个数是偶数，则将所述第一亮度值队列中前半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中后半部分的亮度值组成所述第二亮度集合。或者，将所述预设位置的色度像素对应的亮度像素的亮度值按照从大到小的顺序进行排列，得到第二亮度值队列；如果所述第二亮度值队列中的亮度像素的个数是偶数，则将所述第二亮度值队列中后半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中前半部分的亮度值组成所述第二亮度集合。
本申请实施例所示的方案，将获取到的亮度值按照从小到大的顺序进行排列，得到第一亮度值队列，如果第一亮度值队列中的亮度像素的个数是偶数，则可以确定第一亮度值队列中前半部分的亮度值，将这些亮度值组成第一亮度集合，并且可以确定第一亮度值队列中后半部分的亮度值，将这些亮度值组成第二亮度集合。或者，将获取到的亮度值按照从大到小 的顺序进行排列，得到第二亮度值队列，如果第二亮度值队列中的亮度像素的个数是偶数，则可以确定第二亮度值队列中后半部分的亮度值，将这些亮度值组成第一亮度集合，并且可以确定第二亮度值队列中前半部分的亮度值，将这些亮度值组成第二亮度集合。
这样，可以在不降低编码性能的情况下，提升色度块的预测速度。
在一种可能的实施方式中，所述根据所述第一亮度集合中亮度值的均值、所述第二亮度集合中亮度值的均值、所述第一色度集合中色度值的均值和所述第二色度集合中色度值的均值，确定所述色度块对应的线性模型中的缩放系数，包括：
Figure PCTCN2019124399-appb-000002
其中，α为所述色度块对应的线性模型中的缩放系数，C Lmean为所述第一色度集合中色度值的均值，C Rmean为所述第二色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值，L Rmean为所述第二亮度集合中亮度值的均值。
在一种可能的实施方式中，所述根据所述缩放系数，确定所述色度块对应的线性模型中的偏移因子，包括：根据所述缩放系数、所述第一色度集合中色度值的均值和所述第一亮度集合中亮度值的均值，确定所述色度块对应的线性模型中的偏移因子。
本申请实施例所示的方案，可以确定第一色度集合中色度值的均值，并且可以确定第一亮度集合中亮度值的均值，然后使用缩放系数、第一色度集合中色度值的均值和第一亮度集合中亮度值的均值，确定色度块对应的线性模型中的偏移因子。
在一种可能的实施方式中，所述根据所述缩放系数、所述第一色度集合中色度值的均值和所述第一亮度集合中亮度值的均值，确定所述色度块对应的偏移因子，包括：β＝C Lmean-α*L Lmean，其中，α为所述缩放系数，β为所述色度块对应的线性模型中的偏移因子，C Lmean为所述第一色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值。
在一种可能的实施方式中，所述根据所述缩放系数，确定所述色度块对应的线性模型中的偏移因子，包括：根据所述缩放系数、所述预设位置的色度像素的色度值的均值和所述色度像素对应的亮度像素的亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子。
本申请实施例所示的方案，可以确定获取到的所有色度值的均值，并且可以确定获取到的所有亮度值的均值，然后使用缩放系数、所有色度值的均值和所有亮度值的均值，确定色度块对应的线性模型中的偏移因子。
在一种可能的实施方式中，所述根据所述缩放系数、所述预设位置的色度像素的色度值的均值和所述色度像素对应的亮度像素的亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子，包括：β＝C mean-α*L mean，其中，α为所述缩放系数，β为所述色度块对应的所述线性模型中的偏移因子，C mean为所述预设位置的色度像素的色度值的均值，L mean为所述预设位置的色度像素对应的亮度像素的亮度值的均值。
第二方面，提供了一种色度块的预测装置，所述预测装置包括处理器和存储器，所述存储器用于存储所述处理器可执行指令，所述处理器通过执行指令来实现上述第一方面所提供的色度块的预测方法。
第三方面，提供了一种色度块的预测装置，所述装置包括一个或多个模块，用于实现上述第一方面所提供的色度块的预测方法。
第四方面，提供了一种计算机可读存储介质，计算机可读存储介质存储有指令，当计算机可读存储介质在计算设备上运行时，使得计算设备执行上述第一方面所提供的色度块的预 测方法。
第五方面，提供了一种包含指令的计算机程序产品，当其在计算设备上运行时，使得计算设备执行上述第一方面所提供的色度块的预测方法。
本申请实施例提供的技术方案带来的有益效果至少包括：
本申请实施例中，在进行编码或解码时，可以从色度块的相邻像素中，获取预设位置的色度像素的色度值，然后从色度块对应的亮度块的相邻像素中，获取预设位置的色度像素对应的亮度像素的亮度值，将获取到的亮度值分为第一亮度集合和第二亮度集合，然后基于亮度值的分组，将色度值相应的分为两个集合，即第一色度集合和第二色度集合。然后可以根据第一亮度集合中亮度值的均值、第二亮度集合中亮度值的均值、第一色度集合中色度值的均值和第二色度集合中色度值的均值，确定色度块对应的线性模型中的缩放系数，在确定出缩放系数后，可以使用缩放系数确定色度块对应的线性模型中的偏移因子，最后使用缩放系数、偏移因子和色度块对应的亮度重建信息，确定色度块的预测信息。这样，在编码或者解码时，选取出预设数目个色度值和预设数目个亮度值，然后划分成两个亮度集合和两个色度集合，基于各亮度集合中亮度值的均值和各色度集合中色度值的均值，确定出色度块的缩放系数，进而确定出偏移因子，并没有使用大量的乘法，所以可以节约编码时间和解码时间。
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图1示出用于实现本申请实施例的视频编码系统实例的框图；
图2示出包含图3的编码器20和图4的解码器30中的任一个或两个的视频编码系统实例的框图；
图3示出用于实现本申请实施例的视频编码器实例结构的框图；
图4示出用于实现本申请实施例的视频解码器实例结构的框图；
图5绘示一种编码装置或解码装置实例的框图；
图6绘示另一种编码装置或解码装置实例的框图；
图7示出YUV格式采样网格示例；
图8示出跨分量预测模式的一种实施例；
图9示出一种相邻像素示意图；
图10示出一种相邻像素的另一种示意图；
图11示出色度块的预测方法的流程示意图；
图12示出建立的直角坐标系的示意图；
图13示出预设位置的色度像素的示意图；
图14示出预设位置的色度像素的示意图；
图15示出预设位置的色度像素的示意图；
图16示出预设位置的色度像素的示意图；
图17示出色度块的预测装置的结构示意图。
具体实施方式
为使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请实施方式作进一步地详细描述。
为了便于对本申请的理解，下面首先介绍本申请涉及的系统架构、以及所涉及到名词的概念。
视频编码通常是指处理形成视频或视频序列的图片序列。在视频编码领域，术语“图片(picture)”、“帧(frame)”或“图像(image)”可以用作同义词。本申请(或本公开)中使用的视频编码表示视频编码或视频解码。视频编码在源侧执行，通常包括处理(例如，通过压缩)原始视频图片以减少表示该视频图片所需的数据量，从而更高效地存储和/或传输。视频解码在目的地侧执行，通常包括相对于编码器作逆处理，以重构视频图片。实施例涉及的视频图片“编码”应理解为涉及视频序列的“编码”或“解码”。编码部分和解码部分的组合也称为编解码(编码和解码，或者简称为编码)。
视频序列的每个图片通常分割成不重叠的块集合，通常在块层级上进行编码。换句话说，编码器侧通常在块(也称为图像块，或视频块)层级处理亦即编码视频，例如，通过空间(图片内)预测和时间(图片间)预测来产生预测块，从当前块(当前处理或待处理的块)减去预测块以获取残差块，在变换域变换残差块并量化残差块，以减少待传输(压缩)的数据量，而解码器侧将相对于编码器的逆处理部分应用于经编码或经压缩块，以重构用于表示的当前块。另外，编码器复制解码器处理循环，使得编码器和解码器生成相同的预测(例如帧内预测和帧间预测)和/或重构，用于处理亦即编码后续块。
术语“块”可以为图片或帧的一部分。本申请对关键术语进行如下定义：
当前块：指当前正在处理的块。例如在编码中，指当前正在编码的块；在解码中，指当前正在解码的块。如果当前处理的块为色度分量块，则称为当前色度块。当前色度块对应的亮度块可以称为当前亮度块。
参考块：指为当前块提供参考信号的块。在搜索过程中，可以遍历多个参考块，寻找最佳参考块。
预测块：为当前块提供预测的块称为预测块。例如，在遍历多个参考块以后，找到了最佳参考块，此最佳参考块将为当前块提供预测，此块称为预测块。
图像块信号：图像块内的像素值或者采样值或者采样信号。
预测信号：预测块内的像素值或者采样值或者采样信号，称为预测信号。
以下基于图1、图2到4描述编码器20、解码器30和编码系统10的实施例。
图1为绘示示例性编码系统10的概念性或示意性框图，例如，可以利用本申请(本公开)技术的视频编码系统10。视频编码系统10的编码器20(例如，视频编码器20)和解码器30(例如，视频解码器30)表示可用于根据本申请中描述的各种实例执行用于帧内预测的设备实例。如图1中所示，编码系统10包括源设备12，用于向例如解码经编码数据13的目的地设备14提供经编码数据13，例如，经编码图片13。
源设备12包括编码器20，另外可选地，可以包括图片源16，例如图片预处理单元18的预处理单元18，以及通信接口或通信单元22。
图片源16可以包括或可以为任何类别的图片捕获设备，用于例如捕获现实世界图片，和/或任何类别的图片或评论(对于屏幕内容编码，屏幕上的一些文字也认为是待编码的图片或图像的一部分)生成设备，例如，用于生成计算机动画图片的计算机图形处理器，或用于获取和/或提供现实世界图片、计算机动画图片(例如，屏幕内容、虚拟现实(virtual reality，VR)图片)的任何类别设备，和/或其任何组合(例如，实景(augmented reality，AR)图片)。
图片可以视为具有亮度值的采样点的二维阵列或矩阵。阵列中的采样点也可以称为像素(pixel)(像素(picture element)的简称)或像素(pel)。阵列或图片在水平和垂直方向(或轴线)上的采样点数目定义图片的尺寸和/或分辨率。为了表示颜色，通常采用三个颜色分量，即图片可以表示为或包含三个采样阵列。RBG格式或颜色空间中，图片包括对应的红色、绿色及蓝色采样阵列。但是，在视频编码中，每个像素通常以亮度/色度格式或颜色空间表示，例如，YCbCr，包括Y指示的亮度分量(有时也可以用L指示)以及Cb和Cr指示的两个色度分量。亮度(简写为luma)分量Y表示亮度或灰度水平强度(例如，在灰度等级图片中两者相同)，而两个色度(简写为chroma)分量Cb和Cr表示色度或颜色信息分量。相应地，YCbCr格式的图片包括亮度采样值(Y)的亮度采样阵列，和色度值(Cb和Cr)的两个色度采样阵列。RGB格式的图片可以转换或变换为YCbCr格式，反之亦然，该过程也称为色彩变换或转换。如果图片是黑贝的，该图片可以只包括亮度采样阵列。
图片源16(例如，视频源16)可以为，例如用于捕获图片的相机，例如图片存储器的存储器，包括或存储先前捕获或产生的图片，和/或获取或接收图片的任何类别的(内部或外部)接口。相机可以为，例如，本地的或集成在源设备中的集成相机，存储器可为本地的或例如集成在源设备中的集成存储器。接口可以为，例如，从外部视频源接收图片的外部接口，外部视频源例如为外部图片捕获设备，比如相机、外部存储器或外部图片生成设备，外部图片生成设备例如为外部计算机图形处理器、计算机或服务器。接口可以为根据任何专有或标准化接口协议的任何类别的接口，例如有线或无线接口、光接口。获取图片数据17的接口可以是与通信接口22相同的接口或是通信接口22的一部分。
区别于预处理单元18和预处理单元18执行的处理，图片或图片数据17(例如，视频数据16)也可以称为原始图片或原始图片数据17。
预处理单元18用于接收(原始)图片数据17并对图片数据17执行预处理，以获取经预处理的图片19或经预处理的图片数据19。例如，预处理单元18执行的预处理可以包括整修、色彩格式转换(例如，从RGB转换为YCbCr)、调色或去噪。可以理解，预处理单元18可以是可选组件。
编码器20(例如，视频编码器20)用于接收经预处理的图片数据19并提供经编码图片数据21(下文将进一步描述细节，例如，基于图3或图5)。在一个实例中，编码器20可以用于执行下述实施例一至七。
源设备12的通信接口22可以用于接收经编码图片数据21并传输至其它设备，例如，目的地设备14或任何其它设备，以用于存储或直接重构，或用于在对应地存储经编码数据13和/或传输经编码数据13至其它设备之前处理经编码图片数据21，其它设备例如为目的地设备14或任何其它用于解码或存储的设备。
目的地设备14包括解码器30(例如，视频解码器30)，另外亦即可选地，可以包括通信接口或通信单元28、后处理单元32和显示设备34。
目的地设备14的通信接口28用于例如，直接从源设备12或任何其它源接收经编码图片数据21或经编码数据13，任何其它源例如为存储设备，存储设备例如为经编码图片数据存储设备。
通信接口22和通信接口28可以用于藉由源设备12和目的地设备14之间的直接通信链路或藉由任何类别的网络传输或接收经编码图片数据21或经编码数据13，直接通信链路例 如为直接有线或无线连接，任何类别的网络例如为有线或无线网络或其任何组合，或任何类别的私网和公网，或其任何组合。
通信接口22可以例如用于将经编码图片数据21封装成合适的格式，例如包，以在通信链路或通信网络上传输。
形成通信接口22的对应部分的通信接口28可以例如用于解封装经编码数据13，以获取经编码图片数据21。
通信接口22和通信接口28都可以配置为单向通信接口，如图1中用于经编码图片数据13的从源设备12指向目的地设备14的箭头所指示，或配置为双向通信接口，以及可以用于例如发送和接收消息来建立连接、确认和交换任何其它与通信链路和/或例如经编码图片数据传输的数据传输有关的信息。
解码器30用于接收经编码图片数据21并提供经解码图片数据31或经解码图片31(下文将进一步描述细节，例如，基于图4或图6)。在一个实例中，解码器30可以用于执行下述实施例一至七。
目的地设备14的后处理器32用于后处理经解码图片数据31(也称为经重构图片数据)，例如，经解码图片131，以获取经后处理图片数据33，例如，经后处理图片33。后处理单元32执行的后处理可以包括，例如，色彩格式转换(例如，从YCbCr转换为RGB)、调色、整修或重采样，或任何其它处理，用于例如准备经解码图片数据31以由显示设备34显示。
目的地设备14的显示设备34用于接收经后处理图片数据33以向例如用户或观看者显示图片。显示设备34可以为或可以包括任何类别的用于呈现经重构图片的显示器，例如，集成的或外部的显示器或监视器。例如，显示器可以包括液晶显示器(liquid crystal display，LCD)、有机发光二极管(organic light emitting diode，OLED)显示器、等离子显示器、投影仪、微LED显示器、硅基液晶(liquid crystal on silicon，LCoS)、数字光处理器(digital light processor，DLP)或任何类别的其它显示器。
虽然图1将源设备12和目的地设备14绘示为单独的设备，但设备实施例也可以同时包括源设备12和目的地设备14或同时包括两者的功能性，即源设备12或对应的功能性以及目的地设备14或对应的功能性。在此类实施例中，可以使用相同硬件和/或软件，或使用单独的硬件和/或软件，或其任何组合来实施源设备12或对应的功能性以及目的地设备14或对应的功能性。
本领域技术人员基于描述明显可知，不同单元的功能性或图1所示的源设备12和/或目的地设备14的功能性的存在和(准确)划分可能根据实际设备和应用有所不同。
编码器20(例如，视频编码器20)和解码器30(例如，视频解码器30)都可以实施为各种合适电路中的任一个，例如，一个或多个微处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application-specific integrated circuit，ASIC)、现场可编程门阵列(field-programmable gate array，FPGA)、离散逻辑、硬件或其任何组合。如果部分地以软件实施所述技术，则设备可将软件的指令存储于合适的非暂时性计算机可读存储介质中，且可使用一或多个处理器以硬件执行指令从而执行本公开的技术。前述内容(包含硬件、软件、硬件与软件的组合等)中的任一者可视为一或多个处理器。视频编码器20和视频解码器30中的每一个可以包含在一或多个编码器或解码器中，所述编码器或解码器中的任一个可以集成为对应设备中的组合编码器/解码器(编解码器)的一部分。
源设备12可称为视频编码设备或视频编码装置。目的地设备14可称为视频解码设备或视频解码装置。源设备12以及目的地设备14可以是视频编码设备或视频编码装置的实例。
源设备12和目的地设备14可以包括各种设备中的任一个，包含任何类别的手持或静止设备，例如，笔记本或膝上型计算机、移动电话、智能电话、平板或平板计算机、摄像机、台式计算机、机顶盒、电视、显示设备、数字媒体播放器、视频游戏控制台、视频流式传输设备(例如内容服务服务器或内容分发服务器)、广播接收器设备、广播发射器设备等，并可以不使用或使用任何类别的操作系统。
在一些情况下，源设备12和目的地设备14可以经装备以用于无线通信。因此，源设备12和目的地设备14可以为无线通信设备。
在一些情况下，图1中所示视频编码系统10仅为示例，本申请的技术可以适用于不必包含编码和解码设备之间的任何数据通信的视频编码设置(例如，视频编码或视频解码)。在其它实例中，数据可从本地存储器检索、在网络上流式传输等。视频编码设备可以对数据进行编码并且将数据存储到存储器，和/或视频解码设备可以从存储器检索数据并且对数据进行解码。在一些实例中，由并不彼此通信而是仅编码数据到存储器和/或从存储器检索数据且解码数据的设备执行编码和解码。
应理解，对于以上参考视频编码器20所描述的实例中的每一个，视频解码器30可以用于执行相反过程。关于信令语法元素，视频解码器30可以用于接收并解析这种语法元素，相应地解码相关视频数据。在一些例子中，视频编码器20可以将语法元素熵编码成经编码视频比特流。在此类实例中，视频解码器30可以解析这种语法元素，并相应地解码相关视频数据。
图2是根据一示例性实施例的包含图3的编码器20和/或图4的解码器30的视频编码系统40的实例的说明图。系统40可以实现本申请的各种技术的组合。在所说明的实施方式中，视频编码系统40可以包含成像设备41、视频编码器20、视频解码器30(和/或藉由处理单元46的逻辑电路47实施的视频编码器)、天线42、一个或多个处理器43、一个或多个存储器44和/或显示设备45。
如图2所示，成像设备41、天线42、处理单元46、逻辑电路47、视频编码器20、视频解码器30、处理器43、存储器44和/或显示设备45能够互相通信。如所论述，虽然用视频编码器20和视频解码器30绘示视频编码系统40，但在不同实例中，视频编码系统40可以只包含视频编码器20或只包含视频解码器30。
在一些实例中，如图2所示，视频编码系统40可以包含天线42。例如，天线42可以用于传输或接收视频数据的经编码比特流。另外，在一些实例中，视频编码系统40可以包含显示设备45。显示设备45可以用于呈现视频数据。在一些实例中，如图2所示，逻辑电路47可以通过处理单元46实施。处理单元46可以包含专用集成电路(application-specific integrated circuit，ASIC)逻辑、图形处理器、通用处理器等。视频编码系统40也可以包含可选处理器43，该可选处理器43类似地可以包含专用集成电路逻辑、图形处理器、通用处理器等。在一些实例中，逻辑电路47可以通过硬件实施，如视频编码专用硬件等，处理器43可以通过通用软件、操作系统等实施。另外，存储器44可以是任何类型的存储器，例如易失性存储器(例如，静态随机存取存储器(Static Random Access Memory，SRAM)、动态随机存储器(Dynamic Random Access Memory，DRAM)等)或非易失性存储器(例如，闪存等)等。在非限制性实例中，存储器44可以由超速缓存内存实施。在一些实例中，逻辑电路47可以访问存储器 44(例如用于实施图像缓冲器)。在其它实例中，逻辑电路47和/或处理单元46可以包含存储器(例如，缓存等)用于实施图像缓冲器等。
在一些实例中，通过逻辑电路实施的视频编码器20可以包含(例如，通过处理单元46或存储器44实施的)图像缓冲器和(例如，通过处理单元46实施的)图形处理单元。图形处理单元可以通信耦合至图像缓冲器。图形处理单元可以包含通过逻辑电路47实施的视频编码器20，以实施参照图2和/或本文中所描述的任何其它编码器系统或子系统所论述的各种模块。逻辑电路可以用于执行本文所论述的各种操作。
视频解码器30可以以类似方式通过逻辑电路47实施，以实施参照图4的解码器30和/或本文中所描述的任何其它解码器系统或子系统所论述的各种模块。在一些实例中，逻辑电路实施的视频解码器30可以包含(通过处理单元2820或存储器44实施的)图像缓冲器和(例如，通过处理单元46实施的)图形处理单元。图形处理单元可以通信耦合至图像缓冲器。图形处理单元可以包含通过逻辑电路47实施的视频解码器30，以实施参照图4和/或本文中所描述的任何其它解码器系统或子系统所论述的各种模块。
在一些实例中，视频编码系统40的天线42可以用于接收视频数据的经编码比特流。如所论述，经编码比特流可以包含本文所论述的与编码视频帧相关的数据、指示符、索引值、模式选择数据等，例如与编码分割相关的数据(例如，变换系数或经量化变换系数，(如所论述的)可选指示符，和/或定义编码分割的数据)。视频编码系统40还可包含耦合至天线42并用于解码经编码比特流的视频解码器30。显示设备45用于呈现视频帧。
编码器&编码方法
图3示出用于实现本申请(公开)技术的视频编码器20的实例的示意性/概念性框图。在图3的实例中，视频编码器20包括残差计算单元204、变换处理单元206、量化单元208、逆量化单元210、逆变换处理单元212、重构单元214、缓冲器216、环路滤波器单元220、经解码图片缓冲器(decoded picture buffer，DPB)230、预测处理单元260和熵编码单元270。预测处理单元260可以包含帧间预测单元244、帧内预测单元254和模式选择单元262。帧间预测单元244可以包含运动估计单元和运动补偿单元(未图示)。图3所示的视频编码器20也可以称为混合型视频编码器或根据混合型视频编解码器的视频编码器。
例如，残差计算单元204、变换处理单元206、量化单元208、预测处理单元260和熵编码单元270形成编码器20的前向信号路径，而例如逆量化单元210、逆变换处理单元212、重构单元214、缓冲器216、环路滤波器220、经解码图片缓冲器230、预测处理单元260形成编码器的后向信号路径，其中编码器的后向信号路径对应于解码器的信号路径(参见图4中的解码器30)。
编码器20通过例如输入202，接收图片201或图片201的块203，例如，形成视频或视频序列的图片序列中的图片。图片块203也可以称为当前图片块或待编码图片块，图片201可以称为当前图片或待编码图片(尤其是在视频编码中将当前图片与其它图片区分开时，其它图片例如同一视频序列亦即也包括当前图片的视频序列中的先前经编码和/或经解码图片)。
分割
编码器20的实施例可以包括分割单元(图3中未绘示)，用于将图片201分割成多个例 如块203的块，通常分割成多个不重叠的块。分割单元可以用于对视频序列中所有图片使用相同的块大小以及定义块大小的对应栅格，或用于在图片或子集或图片群组之间更改块大小，并将每个图片分割成对应的块。
在一个实例中，视频编码器20的预测处理单元260可以用于执行上述分割技术的任何组合。
如图片201，块203也是或可以视为具有亮度值(采样值)的采样点的二维阵列或矩阵，虽然其尺寸比图片201小。换句话说，块203可以包括，例如，一个采样阵列(例如黑白图片201情况下的亮度阵列)或三个采样阵列(例如，彩色图片情况下的一个亮度阵列和两个色度阵列)或依据所应用的色彩格式的任何其它数目和/或类别的阵列。块203的水平和垂直方向(或轴线)上采样点的数目定义块203的尺寸。
如图3所示的编码器20用于逐块编码图片201，例如，对每个块203执行编码和预测。
残差计算
残差计算单元204用于基于图片块203和预测块265(下文提供预测块265的其它细节)计算残差块205，例如，通过逐样本(逐像素)将图片块203的样本值减去预测块265的样本值，以在样本域中获取残差块205。
变换
变换处理单元206用于在残差块205的样本值上应用例如离散余弦变换(discrete cosine transform，DCT)或离散正弦变换(discrete sine transform，DST)的变换，以在变换域中获取变换系数207。变换系数207也可以称为变换残差系数，并在变换域中表示残差块205。
变换处理单元206可以用于应用DCT/DST的整数近似值，例如为HEVC/H.265指定的变换。与正交DCT变换相比，这种整数近似值通常由某一因子按比例缩放。为了维持经正变换和逆变换处理的残差块的范数，应用额外比例缩放因子作为变换过程的一部分。比例缩放因子通常是基于某些约束条件选择的，例如，比例缩放因子是用于移位运算的2的幂、变换系数的位深度、准确性和实施成本之间的权衡等。例如，在解码器30侧通过例如逆变换处理单元212为逆变换(以及在编码器20侧通过例如逆变换处理单元212为对应逆变换)指定具体比例缩放因子，以及相应地，可以在编码器20侧通过变换处理单元206为正变换指定对应比例缩放因子。
量化
量化单元208用于例如通过应用标量量化或向量量化来量化变换系数207，以获取经量化变换系数209。经量化变换系数209也可以称为经量化残差系数209。量化过程可以减少与部分或全部变换系数207有关的位深度。例如，可在量化期间将n位变换系数向下舍入到m位变换系数，其中n大于m。可通过调整量化参数(quantization parameter，QP)修改量化程度。例如，对于标量量化，可以应用不同的标度来实现较细或较粗的量化。较小量化步长对应较细量化，而较大量化步长对应较粗量化。可以通过量化参数指示合适的量化步长。例如，量化参数可以为合适的量化步长的预定义集合的索引。例如，较小的量化参数可以对应精细量化(较小量化步长)，较大量化参数可以对应粗糙量化(较大量化步长)，反之亦然。量化 可以包含除以量化步长以及例如通过逆量化210执行的对应的量化或逆量化，或者可以包含乘以量化步长。根据例如HEVC的一些标准的实施例可以使用量化参数来确定量化步长。一般而言，可以基于量化参数使用包含除法的等式的定点近似来计算量化步长。可以引入额外比例缩放因子来进行量化和反量化，以恢复可能由于在用于量化步长和量化参数的等式的定点近似中使用的标度而修改的残差块的范数。在一个实例实施方式中，可以合并逆变换和反量化的标度。或者，可以使用自定义量化表并在例如比特流中将其从编码器通过信号发送到解码器。量化是有损操作，其中量化步长越大，损耗越大。
逆量化单元210用于在经量化系数上应用量化单元208的逆量化，以获取经反量化系数211，例如，基于或使用与量化单元208相同的量化步长，应用量化单元208应用的量化方案的逆量化方案。经反量化系数211也可以称为经反量化残差系数211，对应于变换系数207，虽然由于量化造成的损耗通常与变换系数不相同。
逆变换处理单元212用于应用变换处理单元206应用的变换的逆变换，例如，逆离散余弦变换或逆离散正弦变换，以在样本域中获取逆变换块213。逆变换块213也可以称为逆变换经反量化块213或逆变换残差块213。
重构单元214(例如，求和器214)用于将逆变换块213(即经重构残差块213)添加至预测块265，以在样本域中获取经重构块215，例如，将经重构残差块213的样本值与预测块265的样本值相加。
可选地，例如线缓冲器216的缓冲器单元216(或简称“缓冲器”216)用于缓冲或存储经重构块215和对应的样本值，用于例如帧内预测。在其它的实施例中，编码器可以用于使用存储在缓冲器单元216中的未经滤波的经重构块和/或对应的样本值来进行任何类别的估计和/或预测，例如帧内预测。
例如，编码器20的实施例可以经配置以使得缓冲器单元216不只用于存储用于帧内预测254的经重构块215，也用于环路滤波器单元220(在图3中未示出)，和/或，例如使得缓冲器单元216和经解码图片缓冲器单元230形成一个缓冲器。其它实施例可以用于将经滤波块221和/或来自经解码图片缓冲器230的块或样本(图3中均未示出)用作帧内预测254的输入或基础。
环路滤波器单元220(或简称“环路滤波器”220)用于对经重构块215进行滤波以获取经滤波块221，从而顺利进行像素转变或提高视频质量。环路滤波器单元220旨在表示一个或多个环路滤波器，例如去块滤波器、样本自适应偏移(sample-adaptive offset，SAO)滤波器或其它滤波器，例如双边滤波器、自适应环路滤波器(adaptive loop filter，ALF)，或锐化或平滑滤波器，或协同滤波器。尽管环路滤波器单元220在图3中示出为环内滤波器，但在其它配置中，环路滤波器单元220可实施为环后滤波器。经滤波块221也可以称为经滤波的经重构块221。经解码图片缓冲器230可以在环路滤波器单元220对经重构编码块执行滤波操作之后存储经重构编码块。
编码器20(对应地，环路滤波器单元220)的实施例可以用于输出环路滤波器参数(例如，样本自适应偏移信息)，例如，直接输出或由熵编码单元270或任何其它熵编码单元熵编码后输出，例如使得解码器30可以接收并应用相同的环路滤波器参数用于解码。
经解码图片缓冲器230可以为存储参考图片数据供视频编码器20编码视频数据之用的参考图片存储器。DPB 230可由多种存储器设备中的任一个形成，例如动态随机存储器(dynamic random access memory，DRAM)(包含同步DRAM(synchronous DRAM，SDRAM)、磁阻式RAM(magnetoresistive RAM，MRAM)、电阻式RAM(resistive RAM，RRAM))或其它类型的存储器设备。可以由同一存储器设备或单独的存储器设备提供DPB 230和缓冲器216。在某一实例中，经解码图片缓冲器(decoded picture buffer，DPB)230用于存储经滤波块221。经解码图片缓冲器230可以进一步用于存储同一当前图片或例如先前经重构图片的不同图片的其它先前的经滤波块，例如先前经重构和经滤波块221，以及可以提供完整的先前经重构亦即经解码图片(和对应参考块和样本)和/或部分经重构当前图片(和对应参考块和样本)，例如用于帧间预测。在某一实例中，如果经重构块215无需环内滤波而得以重构，则经解码图片缓冲器230用于存储经重构块215。
预测处理单元260，也称为块预测处理单元260，用于接收或获取块203(当前图片201的当前块203)和经重构图片数据，例如来自缓冲器216的同一(当前)图片的参考样本和/或来自经解码图片缓冲器230的一个或多个先前经解码图片的参考图片数据231，以及用于处理这类数据进行预测，即提供可以为经帧间预测块245或经帧内预测块255的预测块265。
模式选择单元262可以用于选择预测模式(例如帧内或帧间预测模式)和/或对应的用作预测块265的预测块245或255，以计算残差块205和重构经重构块215。
模式选择单元262的实施例可以用于选择预测模式(例如，从预测处理单元260所支持的那些预测模式中选择)，所述预测模式提供最佳匹配或者说最小残差(最小残差意味着传输或存储中更好的压缩)，或提供最小信令开销(最小信令开销意味着传输或存储中更好的压缩)，或同时考虑或平衡以上两者。模式选择单元262可以用于基于码率失真优化(Rate Distortion Optimization，RDO)确定预测模式，即选择提供最小码率失真优化的预测模式，或选择相关码率失真至少满足预测模式选择标准的预测模式。
下文将详细解释编码器20的实例(例如，通过预测处理单元260)执行的预测处理和(例如，通过模式选择单元262)执行的模式选择。
如上文所述，编码器20用于从(预先确定的)预测模式集合中确定或选择最好或最优的预测模式。预测模式集合可以包括例如帧内预测模式和/或帧间预测模式。
帧内预测模式集合可以包括35种不同的帧内预测模式，或者可以包括67种不同的帧内预测模式，或者可以包括正在发展中的H.266中定义的帧内预测模式。
帧间预测模式集合取决于可用参考图片(即，例如前述存储在DBP 230中的至少部分经解码图片)和其它帧间预测参数，例如取决于是否使用整个参考图片或只使用参考图片的一部分，例如围绕当前块的区域的搜索窗区域，来搜索最佳匹配参考块，和/或例如取决于是否应用如半像素和/或四分之一像素内插的像素内插。
除了以上预测模式，也可以应用跳过模式和/或直接模式。
预测处理单元260可以进一步用于将块203分割成较小的块分区或子块，例如，通过迭 代使用四叉树(quad-tree，QT)分割、二进制树(binary-tree，BT)分割或三叉树(triple-tree，TT)分割，或其任何组合，以及用于例如为块分区或子块中的每一个执行预测，其中模式选择包括选择分割的块203的树结构和选择应用于块分区或子块中的每一个的预测模式。
帧间预测单元244可以包含运动估计(motion estimation，ME)单元(图3中未示出)和运动补偿(motion compensation，MC)单元(图3中未示出)。运动估计单元用于接收或获取图片块203(当前图片201的当前图片块203)和经解码图片231，或至少一个或多个先前经重构块，例如，一个或多个其它/不同先前经解码图片231的经重构块，来进行运动估计。例如，视频序列可以包括当前图片和先前经解码图片31，或换句话说，当前图片和先前经解码图片31可以是形成视频序列的图片序列的一部分，或者形成该图片序列。
例如，编码器20可以用于从多个其它图片中的同一或不同图片的多个参考块中选择参考块，并向运动估计单元(图3中未示出)提供参考图片和/或提供参考块的位置(X、Y坐标)与当前块的位置之间的偏移(空间偏移)作为帧间预测参数。该偏移也称为运动向量(motion vector，MV)。
运动补偿单元用于获取，例如接收帧间预测参数，并基于或使用帧间预测参数执行帧间预测来获取帧间预测块245。由运动补偿单元(图3中未示出)执行的运动补偿可以包含基于通过运动估计(可能执行对子像素精确度的内插)确定的运动/块向量取出或生成预测块。内插滤波可从已知像素样本产生额外像素样本，从而潜在地增加可用于编码图片块的候选预测块的数目。一旦接收到用于当前图片块的PU的运动向量，运动补偿单元246可以在一个参考图片列表中定位运动向量指向的预测块。运动补偿单元246还可以生成与块和视频条带相关联的语法元素，以供视频解码器30在解码视频条带的图片块时使用。
帧内预测单元254用于获取，例如接收同一图片的图片块203(当前图片块)和一个或多个先前经重构块，例如经重构相邻块，以进行帧内估计。例如，编码器20可以用于从多个帧内预测模式中选择帧内预测模式。
编码器20的实施例可以用于基于优化标准选择帧内预测模式，例如基于最小残差(例如，提供最类似于当前图片块203的预测块255的帧内预测模式)或最小码率失真。
帧内预测单元254进一步用于基于如所选择的帧内预测模式的帧内预测参数确定帧内预测块255。在任何情况下，在选择用于块的帧内预测模式之后，帧内预测单元254还用于向熵编码单元270提供帧内预测参数，即提供指示所选择的用于块的帧内预测模式的信息。在一个实例中，帧内预测单元254可以用于执行下文描述的帧内预测技术的任意组合。
熵编码单元270用于将熵编码算法或方案(例如，可变长度编码(variable length coding，VLC)方案、上下文自适应VLC(context adaptive VLC，CAVLC)方案、算术编码方案、上下文自适应二进制算术编码(context adaptive binary arithmetic coding，CABAC)、基于语法的上下文自适应二进制算术编码(syntax-based context-adaptive binary arithmetic coding，SBAC)、概率区间分割熵(probability interval partitioning entropy，PIPE)编码或其它熵编码方法或技术)应用于经量化残差系数209、帧间预测参数、帧内预测参数和/或环路滤波器参数中的单个或所有上(或不应用)，以获取可以通过输出272以例如经编码比特流21的形式输出的经编码图片数据21。可以将经编码比特流传输到视频解码器30，或将其存档稍后由视频解码器30传输或检索。熵编码单元270还可用于熵编码正被编码的当前视频条带的其它语法元素。
视频编码器20的其它结构变型可用于编码视频流。例如，基于非变换的编码器20可以 在没有针对某些块或帧的变换处理单元206的情况下直接量化残差信号。在另一实施方式中，编码器20可具有组合成单个单元的量化单元208和逆量化单元210。
图4示出示例性视频解码器30，用于实现本申请的技术。视频解码器30用于接收例如由编码器20编码的经编码图片数据(例如，经编码比特流)21，以获取经解码图片231。在解码过程期间，视频解码器30从视频编码器20接收视频数据，例如表示经编码视频条带的图片块的经编码视频比特流及相关联的语法元素。
在图4的实例中，解码器30包括熵解码单元304、逆量化单元310、逆变换处理单元312、重构单元314(例如求和器314)、缓冲器316、环路滤波器320、经解码图片缓冲器330以及预测处理单元360。预测处理单元360可以包含帧间预测单元344、帧内预测单元354和模式选择单元362。在一些实例中，视频解码器30可执行大体上与参照图3的视频编码器20描述的编码遍次互逆的解码遍次。
熵解码单元304用于对经编码图片数据21执行熵解码，以获取例如经量化系数309和/或经解码的编码参数(图4中未示出)，例如，帧间预测、帧内预测参数、环路滤波器参数和/或其它语法元素中(经解码)的任意一个或全部。熵解码单元304进一步用于将帧间预测参数、帧内预测参数和/或其它语法元素转发至预测处理单元360。视频解码器30可接收视频条带层级和/或视频块层级的语法元素。
逆量化单元310功能上可与逆量化单元110相同，逆变换处理单元312功能上可与逆变换处理单元212相同，重构单元314功能上可与重构单元214相同，缓冲器316功能上可与缓冲器216相同，环路滤波器320功能上可与环路滤波器220相同，经解码图片缓冲器330功能上可与经解码图片缓冲器230相同。
预测处理单元360可以包括帧间预测单元344和帧内预测单元354，其中帧间预测单元344功能上可以类似于帧间预测单元244，帧内预测单元354功能上可以类似于帧内预测单元254。预测处理单元360通常用于执行块预测和/或从经编码数据21获取预测块365，以及从例如熵解码单元304(显式地或隐式地)接收或获取预测相关参数和/或关于所选择的预测模式的信息。
当视频条带经编码为经帧内编码(I)条带时，预测处理单元360的帧内预测单元354用于基于信号表示的帧内预测模式及来自当前帧或图片的先前经解码块的数据来产生用于当前视频条带的图片块的预测块365。当视频帧经编码为经帧间编码(即B或P)条带时，预测处理单元360的帧间预测单元344(例如，运动补偿单元)用于基于运动向量及从熵解码单元304接收的其它语法元素生成用于当前视频条带的视频块的预测块365。对于帧间预测，可从一个参考图片列表内的一个参考图片中产生预测块。视频解码器30可基于存储于DPB330中的参考图片，使用默认建构技术来建构参考帧列表：列表0和列表1。
预测处理单元360用于通过解析运动向量和其它语法元素，确定用于当前视频条带的视频块的预测信息，并使用预测信息产生用于正经解码的当前视频块的预测块。例如，预测处理单元360使用接收到的一些语法元素确定用于编码视频条带的视频块的预测模式(例如，帧内或帧间预测)、帧间预测条带类型(例如，B条带、P条带或GPB条带)、用于条带的参考图片列表中的一个或多个的建构信息、用于条带的每个经帧间编码视频块的运动向量、条带的每个经帧间编码视频块的帧间预测状态以及其它信息，以解码当前视频条带的视频块。
逆量化单元310可用于逆量化(即，反量化)在比特流中提供且由熵解码单元304解码 的经量化变换系数。逆量化过程可包含使用由视频编码器20针对视频条带中的每一视频块所计算的量化参数来确定应该应用的量化程度并同样确定应该应用的逆量化程度。
逆变换处理单元312用于将逆变换(例如，逆DCT、逆整数变换或概念上类似的逆变换过程)应用于变换系数，以便在像素域中产生残差块。
重构单元314(例如，求和器314)用于将逆变换块313(即经重构残差块313)添加到预测块365，以在样本域中获取经重构块315，例如通过将经重构残差块313的样本值与预测块365的样本值相加。
环路滤波器单元320(在编码循环期间或在编码循环之后)用于对经重构块315进行滤波以获取经滤波块321，从而顺利进行像素转变或提高视频质量。在一个实例中，环路滤波器单元320可以用于执行下文描述的滤波技术的任意组合。环路滤波器单元320旨在表示一个或多个环路滤波器，例如去块滤波器、样本自适应偏移(sample-adaptive offset，SAO)滤波器或其它滤波器，例如双边滤波器、自适应环路滤波器(adaptive loop filter，ALF)，或锐化或平滑滤波器，或协同滤波器。尽管环路滤波器单元320在图4中示出为环内滤波器，但在其它配置中，环路滤波器单元320可实施为环后滤波器。
随后将给定帧或图片中的经解码视频块321存储在存储用于后续运动补偿的参考图片的经解码图片缓冲器330中。
解码器30用于例如，藉由输出332输出经解码图片31，以向用户呈现或供用户查看。
视频解码器30的其它变型可用于对压缩的比特流进行解码。例如，解码器30可以在没有环路滤波器单元320的情况下生成输出视频流。例如，基于非变换的解码器30可以在没有针对某些块或帧的逆变换处理单元312的情况下直接逆量化残差信号。在另一实施方式中，视频解码器30可以具有组合成单个单元的逆量化单元310和逆变换处理单元312。
图5是根据本申请实施例的视频译码设备400(例如视频编码设备400或视频解码设备400)的结构示意图。视频译码设备400适于实施本文所描述的实施例。在一个实施例中，视频译码设备400可以是视频解码器(例如图1的视频解码器30)或视频编码器(例如图1的视频编码器20)。在另一个实施例中，视频译码设备400可以是上述图1的视频解码器30或图1的视频编码器20中的一个或多个组件。
视频译码设备400包括：用于接收数据的入口端口410和接收单元(Rx)420，用于处理数据的处理器、逻辑单元或中央处理器(CPU)430，用于传输数据的发射器单元(Tx)440和出口端口450，以及，用于存储数据的存储器460。视频译码设备400还可以包括与入口端口410、接收器单元420、发射器单元440和出口端口450耦合的光电转换组件和电光(EO)组件，用于光信号或电信号的出口或入口。
处理器430通过硬件和软件实现。处理器430可以实现为一个或多个CPU芯片、核(例如，多核处理器)、FPGA、ASIC和DSP。处理器430与入口端口410、接收器单元420、发射器单元440、出口端口450和存储器460通信。处理器430包括译码模块470(例如编码模块470或解码模块470)。编码/解码模块470实现上述公开的实施例。例如，编码/解码模块470实现、处理或提供各种编码操作。因此，通过编码/解码模块470为视频译码设备400的功能提供了实质性的改进，并影响了视频译码设备400到不同状态的转换。或者，以存储在存储器460中并由处理器430执行的指令来实现编码/解码模块470。
存储器460包括一个或多个磁盘、磁带机和固态硬盘，可以用作溢出数据存储设备，用 于在选择性地执行这些程序时存储程序，并存储在程序执行过程中读取的指令和数据。存储器460可以是易失性和/或非易失性的，可以是只读存储器(Read Only Memory，ROM)、随机存取存储器(random access memory，RAM)、随机存取存储器(ternary content-addressable memory，TCAM)和/或静态随机存取存储器(SRAM)。
图6是根据一示例性实施例的可用作图1中的源设备12和目的地设备14中的任一个或两个的装置500的简化框图。装置500可以实现本申请的技术，用于实现色度块预测的装置500可以采用包含多个计算设备的计算系统的形式，或采用例如移动电话、平板计算机、膝上型计算机、笔记本电脑、台式计算机等单个计算设备的形式。
装置500中的处理器502可以为中央处理器。或者，处理器502可以为现有的或今后将研发出的能够操控或处理信息的任何其它类型的设备或多个设备。如图6所示，虽然可以使用例如处理器502的单个处理器实践所揭示的实施方式，但是使用一个以上处理器可以实现速度和效率方面的优势。
在一实施方式中，装置500中的存储器504可以为只读存储器设备或随机存取存储器设备。任何其他合适类型的存储设备都可以用作存储器504。存储器504可以包括代码和由处理器502使用总线512访问的数据506。存储器504可进一步包括操作系统508和应用程序510，应用程序510包含至少一个准许处理器502执行本文所描述的方法的程序。例如，应用程序510可以包括应用1到N，应用1到N进一步包括执行本文所描述的方法的视频编码应用。装置500还可包含采用从存储器514形式的附加存储器，该从存储器514例如可以为与移动计算设备一起使用的存储卡。因为视频通信会话可能含有大量信息，这些信息可以整体或部分存储在从存储器514中，并按需要加载到存储器504用于处理。
装置500还可包含一或多个输出设备，例如显示器518。在一个实例中，显示器518可以为将显示器和可操作以感测触摸输入的触敏元件组合的触敏显示器。显示器518可以通过总线512耦合于处理器502。除了显示器518还可以提供其它准许用户对装置500编程或以其它方式使用装置500的输出设备，或提供其它输出设备作为显示器518的替代方案。当输出设备是显示器或包含显示器时，显示器可以以不同方式实现，包含通过液晶显示器、阴极射线管(cathode-ray tube，CRT)显示器、等离子显示器或发光二极管(light emitting diode，LED)显示器，如有机LED(organic LED，OLED)显示器。
装置500还可包含图像感测设备520或与其连通，图像感测设备520例如为相机或为现有的或今后将研发出的可以感测图像的任何其它图像感测设备520，所述图像例如为运行装置500的用户的图像。图像感测设备520可以放置为直接面向运行装置500的用户。在一实例中，可以配置图像感测设备520的位置和光轴以使其视野包含紧邻显示器518的区域且从该区域可见显示器518。
装置500还可包含声音感测设备522或与其连通，声音感测设备522例如为麦克风或为现有的或今后将研发出的可以感测装置500附近的声音的任何其它声音感测设备。声音感测设备522可以放置为直接面向运行装置500的用户，并可以用于接收用户在运行装置500时发出的声音，例如语音或其它发声。
虽然图6中将装置500的处理器502和存储器504绘示为集成在单个单元中，但是还可以使用其它配置。处理器502的运行可以分布在多个可直接耦合的机器中(每个机器具有一个或多个处理器)，或分布在本地区域或其它网络中。存储器504可以分布在多个机器中，例 如基于网络的存储器或多个运行装置500的机器中的存储器。虽然此处只绘示单个总线，但装置500的总线512可以由多个总线形成。进一步地，从存储器514可以直接耦合至装置500的其它组件或可以通过网络访问，并且可包括单个集成单元，例如一个存储卡，或多个单元，例如多个存储卡。因此，可以以多种配置实施装置500。
如本申请前面所述，彩色视频除了含有亮度(Y)分量以外，还含有色度分量(U，V)。因此，除了对亮度分量进行编码，还需要对色度分量进行编码。按照彩色视频中亮度分量和色度分量的采样方法的不同，一般存在YUV4:4:4，YUV4:2:2，YUV4:2:0。如图7所示，其中，叉表示亮度分量采样点，圈表示色度分量采样点。
4:4:4格式：表示色度分量没有下采样；
4:2:2格式：表示色度分量相对于亮度分量进行2:1的水平下采样，没有竖直下采样。对于每两个U采样点或V采样点，每行都包含四个Y采样点；
4:2:0格式：表示色度分量相对于亮度分量进行2:1的水平下采样，与2:1的竖直下采样。
其中，YUV4:2:0最为常见。在视频图像采用YUV4:2:0采样格式的情况下，若图像块的亮度分量为2Mx2N大小的图像块，则图像块的色度分量为MxN大小的图像块。因此，图像块的色度分量在本申请中也称为色度块或者色度分量块。本申请以YUV4:2:0介绍，但是也可以适用于其他亮度分量和色度分量的采样方法。
本申请中，色度图像(picture)中的像素点简称为色度采样点(chroma sample)，或者色度点；亮度图像(picture)中的像素点简称为亮度采样点(luma sample)，或者亮度点。
与亮度分量类似，色度帧内预测也是利用当前色度块周围相邻已重建块的边界像素作为当前块的参考像素，按照一定的预测模式将参考像素映射到当前色度块内的像素点，作为当前色度块内像素的预测值。所不同的是，由于色度分量的纹理一般较为简单，所以色度分量帧内预测模式的数量一般少于亮度分量。
跨分量预测模式又称跨分量帧内预测模式，或者CCLM预测模式。其中CCLM预测模式又可简称线性模型模式。LM模式(简称为线性模型，或者线性模式)，是一种利用亮度和色度之间纹理相关性的色度帧内预测方法。LM使用重建亮度分量按照线性模型导出当前色度块预测值，可以表示为下式：
pred C(i,j)＝α*rec i L(i,j)+β     (1)
α，β均为线性模型系数，α缩放系数，β为偏移因子，pred C(i,j)为(i,j)位置上的色度像素的预测值，rec i L(i,j)为当前色度块对应亮度重建块(下文简称为对应亮度块)下采样至色度分量分辨率后(i,j)位置上的亮度重建像素值。对于YUV4:2:0格式的视频，亮度分量的分辨率是色度分量分辨率的4倍(宽高各两倍)，为了得到与色度块同分辨率的亮度块，需要将亮度分量按照色度分量相同的下采样方法下采样至色度分辨率，再进行使用。
线性模型系数并不需要编码传输，而是使用当前色度块的相邻已重建块的边缘像素以及所述边缘像素对应位置的亮度像素,导出α，β。如图8为跨分量预测模式的一个实施例。在图8中，recL为重建的亮度块(当前色度块对应亮度块以及相邻参考像素)，recL’为下采样后的亮度块，recC’为当前色度块的相邻已重建参考像素。当前色度块的尺寸为WxH，以其相邻上侧和左侧的相邻已重建像素为参考像素，对应的luma块的尺寸为2Wx2H，将luma块以及luma块参考像素进行下采样至色度分辨率，得到图8(b)所示像素块。图8(b)和图8(c)中的相邻参考像素构成一一对应关系。
为了便于说明，本申请将用于计算线性模型系数的相邻上侧像素和相邻左侧像素称为相邻像素，上侧为相邻上侧像素，左侧为相邻左侧像素。与色度块相邻的像素称为相邻像素(其中包括相邻上侧像素和相邻左侧像素)，与亮度块相邻的像素称为相邻像素(其中包括相邻的上侧像素和相邻的左侧像素)。色度像素与亮度像素一一对应，并且采样点的值构成值对。
本申请实施例中，亮度像素一般需要通过下采样获得(由于亮度分量分辨率与色度不同),表示为Luma’samples。色度像素(Chroma samples)一般为当前色度块相邻上侧一行或者两行像素点，以及左侧一列或者两列像素点。附图9中为使用一行一列的示意图，附图10中为使用两行两列的示意图。
LM模式能够有效利用亮度分量和色度分量之间的相关性，相比于方向预测模式，LM方法更加灵活，从而为色度分量提供更加准确的预测信号。
另外，还存在多线性模型(Multiple model linear model，简称MMLM)模式，存在多个α和β。以两个线性模型为例，存在两组线性模型系数，α 1，β 1以及α 2，β 2。
本申请提供了一种色度块的预测方法，下面将结合具体实施方式，对图11所示的处理流程进行详细的说明，本过程在编码过程以及解码过程中均存在，本申请实施例以解码端为例进行方案的说明，内容可以如下：
步骤1101，从色度块的相邻像素中，获取预设位置的色度像素的色度值。
其中，色度块为当前要进行帧内预测的色度块。预设位置的色度像素的个数(可以简称为预设数目)可以预设，如预设数目为2、4、6、8等。色度块的相邻像素指与色度块相邻的已重建像素，见上述图9和图10。
在具体的实施方式中，在对当前色度块(后续可以简称为色度块)进行帧内预测时，可以从色度块的相邻像素中，获取预设位置的色度像素的色度值。可以表示为一个集合φ，φ＝{C 0,C 1,...,C M-1}，其中，M表示预设数目，即获取到的色度值的数目。
可选的，线性模式(也可以称为帧内线性预测模式)仅有一种时，在后续图12所示的坐标系下，预设位置一般为(0，-1)(X-1，-1)、(-1，0)、(-1，Y-1)，可以从色度块的相邻像素中，获取预设位置的色度像素的色度值。
可选的，解码端可以基于码流中的指示信息，确定色度块对应的帧内预测模式，并且根据帧内预测模式，确定预设位置，相应的处理可以如下：
获取指示信息，基于指示信息确定色度块对应的帧内预测模式，根据色度块对应的帧内预测模式，确定预设位置。
其中，色度块对应的帧内预测模式可以包括LM、LMA和LML中的至少一种。指示信息用于指示色度块对应的帧内预测模式。
在具体的实施方式中，在编码端进行编码时，将色度块对应的帧内预测模式进行编码，然后发送至解码端(此过程在后面进行说明)。
解码端可以在接收到的码流中，获取指示信息，基于该指示信息确定色度块对应的帧内预测模式。后续解码端可以根据色度块对应的帧内预测模式，确定出预设位置。
可选的，指示信息可以设置在语法表中，如表一所示：
表一
Figure PCTCN2019124399-appb-000003
在表一中，语法表中的语法元素CuPredMode[x0][y0]用于指示当前的色度块的预测模式是帧内预测模式还是帧间预测模式。例如，CuPredMode[x0][y0]为MODE_INTRA，表示当前的色度块使用帧内预测模式，CuPredMode[x0][y0]为MODE_INTER表示当前的色度块使用帧间预测模式。x0，y0表示当前色度块在视频图像中的坐标。
语法元素intra_chroma_pred_mode[x0][y0]用于指示当前的色度块的帧内预测模式信息(也即上述提到的指示信息)。例如，intra_chroma_pred_mode[x0][y0]＝0表示当前块使用LM0模式，intra_chroma_pred_mode[x0][y0]＝1表示当前的是色度块使用LM1模式，intra_chroma_pred_mode[x0][y0]＝2表示当前的色度块使用LM2，……，intra_chroma_pred_mode[x0][y0]＝N-1表示当前的色度块使用LM(N-1)，其中，N指示当前的色度块在编码端可选择的N种不同的LM。LM0、LM1，……，LM(N-1)表示不同的帧内预测模式。
可选的，线性模式有多种时，针对不同的线性模式，有不同的预设位置，相应的步骤1101的处理可以如下：
根据预设的帧内预测模式和预设位置的对应关系，以及色度块对应的帧内预测模式，在色度块的相邻像素中，获取预设位置的色度像素的色度值。
在具体的实施方式中，在解码端进行解码时，可以确定色度块对应的帧内预测模式，然后获取预设的帧内预测模式和预设位置的对应关系，在该对应关系中，确定该色度块的帧内预测模式对应的预设位置。然后在色度块的相邻像素中，获取预设位置的色度像素的色度值。
需要说明的是，在上述对应关系中，记录的预设位置可以是预设位置的位置坐标。
可选的，为了更好描述预设位置，如图12所示，本申请实施例对应色度块建立一个平面直角坐标，以色度块的左上角的第一个色度像素为坐标原点，水平向右为x轴的正方向，竖直向下为y轴的正方向。这样，色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)，色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，X表示色度块的宽度(即色度块的宽度方向上像素的数目)，Y表示色度块的高度(即色度块的高度方向上像素的数目)。
如果帧内预测模式为LM0，则在对应关系中，预设位置的位置坐标可以为(0，-1)(X-1，-1)(-1,0)(-1，Y-1)。
如果帧内预测模式为LM1，则在对应关系中，预设位置的位置坐标可以为(0，-1)(X/4， -1)(X-1-X/4，-1)(X-1，-1)。
如果帧内预测模式为LM2，则在对应关系中，预设位置的位置坐标可以为(-1,0)(-1，Y/4)(-1,Y-1-Y/4)(-1，Y-1)。
如果帧内预测模式为LM3，则在对应关系中，预设位置的位置坐标可以为(X-2，-1)(X-1，-1)(-1,Y-2)(-1，Y-1)。
……
如果帧内预测模式为LM(N-1)，则在对应关系中，预设位置的位置坐标可以为(0，-1)(1，-1)(X-2，-1)(X-1，-1)。
可见，在线性模式有多种时，不同的线性模式，可以对应不同的预设位置。
另外，在线性模式为LM、LMA和LML时，还分别列出了预设位置的位置坐标，可以如下：
如果帧内预测模式为LM，则在对应关系中，预设位置的位置坐标可以为(0，-1)(X-1，-1)、(-1，0)、(-1，Y-1)，见图13的中有斜线阴影的圆圈。
如果帧内预测模式为LMA，则在对应关系中，预设位置的位置坐标可以为(0，-1)、(X/4，-1)、(X-1-X/4，-1)、(X-1，-1)，见图14的(a)中有斜线阴影的圆圈，或者(0，-1)(X/4，-1)(3*X/4，-1)(X-1，-1)，见图14的(b)中有斜线阴影的圆圈。
如果帧内预测模式为LML，则在对应关系中，预设位置的位置坐标可以为(-1，0)(-1，Y/4)(-1，Y-1-Y/4)(-1，Y-1)，见图15的(a)中有斜线阴影的圆圈，或者(-1，0)(-1，Y/4)(-1，3*Y/4)(-1，Y-1)，见图15的(b)中有斜线阴影的圆圈。
需要说明的是，上述预设位置的位置坐标仅为举例形式，本申请实施例不做限定。
另外，在帧内预测模式为LM时，上述预设数目还可以为2，预设位置的位置坐标可以为(X-1，-1)和(-1，Y-1)，见图16的(a)中有斜线阴影的圆圈，也可以为(X/2，-1)和(-1，Y/2)，见图16的(b)中有斜线阴影的圆圈，还可以为(X/2，-1)和(-1，Y-1)，见图16的(c)中有斜线阴影的圆圈，还可以为(X-1，-1)和(-1，Y/2)，见图16的(d)中有斜线阴影的圆圈。这些仅是举例形式，本申请实施例不做限定。
需要说明的是，上述的X和Y一般都大于或等于4，且上述图13和图16中X取8、Y取8，上述图14的(a)X取8，图14的(b)X取16，上述图15的(a)Y取8，图15的(b)Y取16。上述的取值仅为一种可能的实施方式，本申请实施例不做限定。另外在图12至16中，方框表示色度块。
步骤1102，基于色度块对应的亮度块的相邻像素，获取预设位置的色度像素对应的亮度像素的亮度值。
在具体的实施方式中，在获取到色度值后，可以确定色度块对应的亮度块，然后从亮度块的相邻像素中，获取预设位置的色度像素对应的亮度像素的亮度值。可以表示为一个集合ψ，ψ＝{L 0,L 1,...,L M-1}，其中，M表示预设数目，即获取到的亮度值的数目。
可选的，针对步骤1102，可以有多种方式可以来来选择亮度值，以下给出两种可行的处理方式：
方式一，在亮度块的相邻像素中，确定预设位置中第i个预设位置的色度像素对应的亮度像素的位置坐标为(2*X i，2*Y i)，其中，第i个预设位置的色度像素的位置坐标为(X i，Y i)，根据预设位置的色度像素对应的亮度像素的位置坐标，从色度块对应的亮度块的相邻像 素中，获取预设位置的色度像素对应的亮度像素的亮度值。
其中，第i个预设位置为预设位置中任一预设位置。
在具体的实施方式中，在对色度块进行解码时，预设位置中第i个预设位置的色度像素的位置坐标为(X i，Y i)(X i为第i个预设位置在图12所示的坐标系下的横坐标，Y i为第i个预设位置在图12所示的坐标系下的纵坐标)，可以在亮度块的相邻像素中，确定第i个预设位置的色度像素对应的亮度像素的位置坐标为(2*X i，2*Y i)。这样，可以得到预设位置的色度像素对应的亮度像素的位置坐标。然后可以使用预设位置的色度像素对应的亮度像素的位置坐标，从相应的亮度像素，获取亮度值。
方式二，根据预设位置中第j个预设位置的位置坐标，在亮度块的相邻像素中，确定第j个预设位置对应的多个采样点的位置坐标；根据多个采样点的位置坐标，确定第j个预设位置的色度像素对应的亮度像素的位置坐标；根据预设位置的色度像素对应的亮度像素的位置坐标，从色度块对应的亮度块的相邻像素中，获取预设位置的色度像素对应的亮度像素的亮度值。
其中，第j个预设位置为预设位置中任一预设位置。
在具体的实施方式中，在对色度块进行解码时，预设位置中第j个预设位置的色度像素的位置坐标为(X j，Y j)(X j为第j个预设位置在图12所示的坐标系下的横坐标，Y j为第j个预设位置在图12所示的坐标系下的纵坐标)，对于第j个预设位置的色度像素，可以根据第j个预设位置的色度像素的位置坐标，确定(X j，Y j)对应到亮度块的相邻像素的多个采样点位置，然后基于这多个采样点位置的位置坐标，得到第j个预设位置的色度像素对应的亮度像素的位置坐标。
例如，可以使用加权的方式，多个采样点位置的位置坐标可以为：(2*Xj,2*Yj)，(2*Xj,2*Yj+1)，(2*Xj+1,2*Yj)，(2*Xj+1,2*Yj+1)，(2*Xj+2,2*Yj)，(2*Xj+2,2*Yj+1)，对应每个采样点位置均有一个权值，分别为2/8、1/8、1/8、2/8、1/8、1/8，进行加权之后，即可得到第j个预设位置的色度像素对应的亮度像素的位置坐标为(2*Xj,2*Yj+0.5)。另外，也可以不采用加权方式，本申请实施例不做限定。这样，可以得到预设位置的色度像素对应的亮度像素的位置坐标。然后可以使用预设位置的色度像素对应的亮度像素的位置坐标，从相应的亮度像素，获取亮度值。
步骤1103，将获取到的亮度值分为第一亮度集合和第二亮度集合。
在具体的实施方式中，在获取到亮度值后，可以将获取到的亮度值分为第一亮度集合和第二亮度集合。
可选的，有多种方式可以得到亮度值集合，本申请实施例提供了三种可行的方式：
方式一：确定预设位置的色度像素对应的亮度像素的亮度值的均值。将预设位置的色度像素对应的亮度像素的亮度值中小于或等于亮度值的均值的亮度值组成第一亮度集合，并将预设位置的色度像素对应的亮度像素的亮度值中大于亮度值的均值的亮度值组成第二亮度集合。
在具体的实施方式中，可以确定步骤1102获取到的亮度值的均值，然后确定步骤1102获取到的亮度值中亮度值小于或等于亮度值的均值的亮度值，将这些亮度值组成第一亮度集合，并且可以确定步骤1102获取到的亮度值中亮度值大于亮度值的均值的亮度值，将这些亮度值组成第二亮度集合，这样，第一亮度集合中的亮度值小于第二亮度集合中的亮度值。
用式子表示为：
亮度值的均值为：
Figure PCTCN2019124399-appb-000004
得到的第一亮度集合为：ψ L＝{L i0,L i1,...,L ij,...,L iS}，其中，L ij≤L mean；
得到的第二亮度集合为：ψ R＝{L j0,L j1,...,L ji,...,L jT}，其中，L ji＞L mean。
方式二：将预设位置的色度像素对应的亮度像素的亮度值按照从小到大的顺序进行排列，得到第一亮度值队列；如果第一亮度值队列中的亮度像素的个数是偶数，则将第一亮度值队列中前半部分的亮度值组成第一亮度集合，并将亮度值队列中后半部分的亮度值组成第二亮度集合。
在具体的实施方式中，可以将步骤1102获取到的亮度值按照从小到大的顺序进行排列，得到第一亮度值队列，如果第一亮度值队列中的亮度像素的个数为偶数，则可以确定第一亮度值队列中前半部分的亮度值，将这些亮度值组成第一亮度集合，并且可以确定第一亮度值队列中后半部分的亮度值，将这些亮度值组成第二亮度集合。
例如，步骤1102中获取到的亮度值有4个，依次为L1,L2,L3,L4，它们之间的大小关系为L4＜L2＜L1＜L3,那么第一亮度值队列为L4，L2，L1，L3，那么第一亮度集合为{L4，L2}，第二亮度集合为{L1，L3}。
方式三：将预设位置的色度像素对应的亮度像素的亮度值按照从大到小的顺序进行排列，得到第二亮度值队列；如果第二亮度值队列中的亮度像素的个数是偶数，则将第二亮度值队列中后半部分的亮度值组成第一亮度集合，并将亮度值队列中前半部分的亮度值组成第二亮度集合。
在具体的实施方式中，可以将步骤1102获取到的亮度值按照从大到小的顺序进行排列，得到第二亮度值队列，如果第二亮度值队列中的亮度像素的个数为偶数，则可以确定第二亮度值队列中后半部分的亮度值，将这些亮度值组成第一亮度集合，并且可以确定第二亮度值队列中前半部分的亮度值，将这些亮度值组成第二亮度集合。
例如，步骤1102中获取到的亮度值有4个，依次为L1,L2,L3,L4，它们之间的大小关系为L3＞L1＞L2＞L4，那么第二亮度值队列为L3，L1，L2，L4，那么第一亮度集合为{L4，L2}，第二亮度集合为{L1，L3}。
另外，上述方式二中第一亮度值队列中的亮度像素的个数为奇数时，如果第一亮度值队列中包括N个亮度值，可以前(N-1)/2个亮度值组成第一亮度集合，后(N+1)/2个亮度值组成第二亮度集合，同样也可以是前(N+1)/2个亮度值组成第一亮度集合，后(N-1)/2个亮度值组成第二亮度集合。同样，上述方式三中第二亮度值队列中的亮度像素的个数为奇数时，如果第二亮度值队列中包括N个亮度值，可以前(N-1)/2个亮度值组成第二亮度集合，后(N+1)/2个亮度值组成第一亮度集合，同样，也可以是前(N+1)/2个亮度值组成第二亮度集合，后(N-1)/2个亮度值组成第一亮度集合。
步骤1104，将第一亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第一色度集合，并将第二亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第二色度集合。
在具体的实施方式中，在得到第一亮度集合和第二亮度集合后，可以将第一亮度集合中所有亮度值对应的色度值，组成第一色度集合，并将第二亮度集合中所有亮度值对应的色度 值，组成第二色度集合。用式子表示可以为：
第一色度集合为：φ L＝{C i0,C i1,...,C ij,...,C iS}；
得到的第二亮度集合为：φ R＝{C j0,C j1,...,C ji,...,C jT}。
需要说明的是，在步骤1101中，在确定亮度值时，使用色度像素对应的亮度像素，此处亮度值对应的色度值，是指亮度值所属的亮度像素对应的色度像素的色度值。
步骤1105，根据第一亮度集合中亮度值的均值、第二亮度集合中亮度值的均值、第一色度集合中色度值的均值和第二色度集合中色度值的均值，确定色度块对应的线性模型中的缩放系数。
在具体的实施方式中，在确定出第一亮度集合、第二亮度集合、第一色度集合和第二色度集合之后，可以确定第一亮度集合中亮度值的均值和第二亮度集合中亮度值的均值，并确定第一色度集合中色度值的均值和第二色度集合中色度值的均值。对应上述方式一，用式子表示为：
第一亮度集合中亮度值的均值：
Figure PCTCN2019124399-appb-000005
第二亮度集合中亮度值的均值：
Figure PCTCN2019124399-appb-000006
第一色度集合中色度值的均值：
Figure PCTCN2019124399-appb-000007
第二色度集合中色度值的均值：
Figure PCTCN2019124399-appb-000008
然后根据第一亮度集合中亮度值的均值、第二亮度集合中亮度值的均值、第一色度集合中色度值的均值和第二色度集合中色度值的均值，确定色度块对应的线性模型中的缩放系数。
可选的，可以使用公式确定缩放系数，相应的处理可以如下：
Figure PCTCN2019124399-appb-000009
其中，α为色度块对应的线性模型中的缩放系数，C Lmean为第一色度集合中色度值的均值，C Rmean为第二色度集合中色度值的均值，L Lmean为第一亮度集合中亮度值的均值，L Rmean为第二亮度集合中亮度值的均值。
在具体的实施方式中，可以获取预设的缩放系数的计算公式，然后将C Lmean，C Rmean，L Lmean和L Rmean代入到缩放系数的计算公式
Figure PCTCN2019124399-appb-000010
中，得到色度块对应的线性模型中的缩放系数。
步骤1106，根据缩放系数，确定色度块对应的线性模型中的偏移因子。
在具体的实施方式中，在确定缩放系数后，可以根据缩放系数，确定色度块对应的线性 模型中的偏移因子，在确定偏移因子时，有多种处理方式，本申请实施例给出两种可行的方式：
方式一：根据缩放系数、第一色度集合中色度值的均值和第一亮度集合中亮度值的均值，确定色度块对应的偏移因子。
在具体的实施方式中，可以确定第一色度集合中色度值的均值：
Figure PCTCN2019124399-appb-000011
并且可以确定第一亮度集合中亮度值的均值：
Figure PCTCN2019124399-appb-000012
然后使用缩放系数、第一色度集合中色度值的均值和第一亮度集合中亮度值的均值，确定色度块对应的偏移因子。
可选的，可以使用如下公式来确定，相应的处理可以如下：
β＝C Lmean-α*L Lmean，其中，α为缩放系数，β为色度块对应的线性模型中的偏移因子，C Lmean为第一色度集合中色度值的均值，L Lmean为第一亮度集合中亮度值的均值。
在具体的实施方式中，可以获取预设的偏移因子的计算公式，然后将步骤1105中得到的缩放系数、C Lmean和L Lmean代入到偏移因子的计算公式β＝C Lmean-α*L Lmean中，得到色度块对应的线性模型中的偏移因子。
方式二：根据缩放系数、预设位置的色度像素的色度值的均值和色度像素对应的亮度像素的亮度值的均值，确定色度块对应的线性模型中的偏移因子。
在具体的实施方式中，可以确定预设位置的色度像素的色度值的均值：
Figure PCTCN2019124399-appb-000013
并且可以确定色度像素对应的亮度像素的亮度值的均值：
Figure PCTCN2019124399-appb-000014
然后使用缩放系数、C mean和L mean，确定色度块对应的偏移因子。
可选的，可以使用如下公式来确定，相应的处理可以如下：
β＝C mean-α*L mean，其中，α为缩放系数，β为色度块对应的线性模型中的偏移因子，C mean为预设位置的色度像素的色度值的均值，L mean为预设位置的色度像素对应的亮度像素的亮度值的均值。
在具体的实施方式中，可以获取预设的偏移因子的计算公式，然后将步骤1105中得到的缩放系数、C mean和L mean代入到偏移因子的计算公式β＝C Lmean-α*L Lmean中，得到色度块对应的线性模型中的偏移因子。
步骤1107，根据缩放系数、偏移因子和色度块对应的亮度重建信息，确定色度块的预测信息。
其中，色度块对应的亮度重建信息包括色度块对应的亮度重建块的下采样信息。
在具体的实施方式中，在得到色度块对应的缩放系数和偏移因子之后，可以使用色度块对应的亮度重建信息、缩放系数和偏移因子，得到色度块的预测信息。
可选的，可以使用公式pred C(i,j)＝α*rec i L(i,j)+β，得到色度块的预测信息，α缩放系数，β为偏移因子，pred C(i,j)为(i,j)位置上的色度像素的预测值，rec i L(i,j)为当前色度块对应亮度块(i,j)位置上的亮度重建像素值。
本申请实施例如果应用到编码端，区别仅在于确定帧内预测模式的方式不相同，在编码端，对于某个色度块，如果确定使用帧内预测方法，则会使用每一种帧内预测模式对色度块进行编码处理，然后使用率失真优化(Rate-distortion optimization，RDO)准则，确定出编码效果最好的帧内预测模式，写入到上述提到的语法表中，添加到码流中，这样，解码端可以直接从码流中确定该采用何种帧内预测模式进行解码。
可选的，使用RDO准则，确定帧内预测模式的方式可以如下：
采用步骤1101至步骤1107的方式确定色度块的预测信息，将色度块的原始信息减去预测信息，得到残差信息，然后对残差信息进行变换，得到变换系数，对变换系数进行量化处理，得到量化系数，对量化系数进行熵编码处理，得到码流。然后对码流依次进行逆熵编码处理、逆量化处理、逆变换处理，进行帧内预测，得到重建信息，将重建信息与原始信息进行对比，将重建信息与原始信息差别最小的帧内预测模式，确定为最终使用的帧内预测模式，也即写入到上述提到的语法表中的帧内预测模式。
需要说明的是，上述提到的编码端可以是使用H.263、H.264、MPEG-2、MPEG-4、VP8、VP9的编码端，相应的解码端也可以是使用H.263、H.264、MPEG-2、MPEG-4、VP8、VP9的解码端。
还需要说明的是，本申请实施例仅以相邻的一行像素为例，本申请实施例也可以应用于图10所示的相邻的两行像素的场景中，处理方式与一排像素时相同，只不过预设数目个的位置点的位置坐标不相同。
本申请实施例中，在进行编码或解码时，可以从色度块的相邻像素中，获取预设位置的色度像素的色度值，然后从色度块对应的亮度块的相邻像素中，获取预设位置的色度像素对应的亮度像素的亮度值，将获取到的亮度值分为第一亮度集合和第二亮度集合，然后基于亮度值的分组，将色度值相应的分为两个集合，即第一色度集合和第二色度集合。然后可以根据第一亮度集合中亮度值的均值、第二亮度集合中亮度值的均值、第一色度集合中色度值的均值和第二色度集合中色度值的均值，确定色度块对应的线性模型中的缩放系数，在确定出缩放系数后，可以使用缩放系数确定色度块对应的线性模型中的偏移因子，最后使用缩放系数、偏移因子和色度块对应的亮度重建信息，确定色度块的预测信息。这样，在编码或者解码时，选取出预设数目个色度值和预设数目个亮度值，然后划分成两个亮度集合和两个色度集合，基于各亮度集合中亮度值的均值和各色度集合中色度值的均值，确定出色度块的缩放系数，进而确定出偏移因子，并没有使用大量的乘法，所以可以节约编码时间和解码时间。
图17是本申请实施例提供的色度块的预测装置的结构图。该装置可以通过软件、硬件或者两者的结合实现成为装置中的部分或者全部。本申请实施例提供的装置可以实现本申请实施例图11至图16所述的流程，该装置包括：获取模块1710、划分模块1720和确定模块1730，其中：
获取模块1710，用于从色度块的相邻像素中，获取预设位置的色度像素的色度值；基于所述色度块对应的亮度块的相邻像素，获取所述预设位置的色度像素对应的亮度像素的亮度 值，具体可以用于实现上述图11的获取功能、以及包含的隐含步骤；
划分模块1720，用于将获取到的亮度值分为第一亮度集合和第二亮度集合；将所述第一亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第一色度集合，并将所述第二亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第二色度集合，具体可以用于实现上述图11的划分功能、以及包含的隐含步骤；
确定模块1730，用于根据所述第一亮度集合中亮度值的均值、所述第二亮度集合中亮度值的均值、所述第一色度集合中色度值的均值和所述第二色度集合中色度值的均值，确定所述色度块对应的线性模型中的缩放系数；根据所述缩放系数，确定所述色度块对应的所述线性模型中的偏移因子；根据所述缩放系数、所述偏移因子和所述色度块对应的亮度重建信息，确定所述色度块的预测信息，其中，所述色度块对应的亮度重建信息包括所述色度块对应的亮度重建块的下采样信息，具体可以用于实现上述图11的确定功能、以及包含的隐含步骤。
可选的，所述获取模块1710，还用于：
获取指示信息，基于所述指示信息确定所述色度块对应的帧内预测模式，其中，所述帧内预测模式包括线性模式LM、上侧线性模式LMA和左侧线性模式LML至少之一；
根据所述色度块对应的帧内预测模式，确定所述预设位置。
可选的，所述获取模块1710，用于：
根据预设的帧内预测模式和预设位置的对应关系，以及色度块对应的帧内预测模式，在所述色度块的相邻像素中，获取所述预设位置的色度像素的色度值。
可选的，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)和所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)；
如果所述色度块对应的帧内预测模式为跨分量线性模式LM，则所述预设位置的色度像素的位置坐标为(0，-1)(X-1，-1)、(-1，0)、(-1，Y-1)。
可选的，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)；
如果所述色度块对应的帧内预测模式为跨分量上侧线性模式LMA，则所述预设位置的位置坐标为(0，-1)、(X/4，-1)、(X-1-X/4，-1)、(X-1，-1)，或者(0，-1)(X/4，-1)(3*X/4，-1)(X-1，-1)。
可选的，所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)；
如果所述色度块对应的帧内预测模式为跨分量左侧线性模式LML，则所述预设位置的位置坐标为(-1，0)(-1，Y/4)(-1，Y-1-Y/4)(-1，Y-1)，或者(-1，0)(-1，Y/4)(-1，3*Y/4)(-1，Y-1)。
可选的，所述获取模块1710，用于：
在所述亮度块的相邻像素中，确定所述预设位置中第i个预设位置的色度像素对应的亮度像素的位置坐标为(2*X i，2*Y i)，其中，所述第i个预设位置的色度像素的位置坐标为(X i，Y i)，根据所述预设位置的色度像素对应的亮度像素的位置坐标，从所述色度块对应的亮度块的相邻像素中，获取所述预设位置的色度像素对应的亮度像素的亮度值；或者，
根据所述预设位置中第j个预设位置的位置坐标，在所述亮度块的相邻像素中，确定所述第j个预设位置对应的多个采样点的位置坐标；根据所述多个采样点的位置坐标，确定所述第j个预设位置的色度像素对应的亮度像素的位置坐标；根据所述预设位置的色度像素对应的亮度像素的位置坐标，从所述色度块对应的亮度块的相邻像素中，获取所述预设位置的 色度像素对应的亮度像素的亮度值。
可选的，所述划分模块1720，用于：
确定所述预设位置的色度像素对应的亮度像素的亮度值的均值；
将所述预设位置的色度像素对应的亮度像素的亮度值中小于或等于所述亮度值的均值的亮度值组成第一亮度集合，并将所述预设位置的色度像素对应的亮度像素的亮度值中大于所述亮度值的均值的亮度值组成第二亮度集合。
可选的，所述划分模块1720，用于：
将所述预设位置的色度像素对应的亮度像素的亮度值按照从小到大的顺序进行排列，得到第一亮度值队列；如果所述第一亮度值队列中的亮度像素的个数是偶数，则将所述第一亮度值队列中前半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中后半部分的亮度值组成所述第二亮度集合；或者，
将所述预设位置的色度像素对应的亮度像素的亮度值按照从大到小的顺序进行排列，得到第二亮度值队列；如果所述第二亮度值队列中的亮度像素的个数是偶数，则将所述第二亮度值队列中后半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中前半部分的亮度值组成所述第二亮度集合。
可选的，所述确定模块1730，用于：
Figure PCTCN2019124399-appb-000015
其中，α为所述色度块对应的线性模型中的缩放系数，C Lmean为所述第一色度集合中色度值的均值，C Rmean为所述第二色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值，L Rmean为所述第二亮度集合中亮度值的均值。
可选的，所述确定模块1730，用于：
根据所述缩放系数、所述第一色度集合中色度值的均值和所述第一亮度集合中亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子。
可选的，所述确定模块1730，用于：
β＝C Lmean-α*L Lmean，其中，α为所述缩放系数，β为所述色度块对应的所述线性模型中的偏移因子，C Lmean为所述第一色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值。
可选的，所述确定模块1730，用于：
根据所述缩放系数、所述预设位置的色度像素的色度值的均值和所述色度像素对应的亮度像素的亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子。
可选的，所述确定模块1730，用于：
β＝C mean-α*L mean，其中，α为所述缩放系数，β为所述色度块对应的所述线性模型中的偏移因子，C mean为所述预设位置的色度像素的色度值的均值，L mean为所述预设位置的色度像素对应的亮度像素的亮度值的均值。
本申请实施例中，在进行编码或解码时，可以从色度块的相邻像素中，获取预设位置的色度像素的色度值，然后从色度块对应的亮度块的相邻像素中，获取预设位置的色度像素对应的亮度像素的亮度值，将获取到的亮度值分为第一亮度集合和第二亮度集合，然后基于亮度值的分组，将色度值相应的分为两个集合，即第一色度集合和第二色度集合。然后可以根据第一亮度集合中亮度值的均值、第二亮度集合中亮度值的均值、第一色度集合中色度值的 均值和第二色度集合中色度值的均值，确定色度块对应的线性模型中的缩放系数，在确定出缩放系数后，可以使用缩放系数确定色度块对应的线性模型中的偏移因子，最后使用缩放系数、偏移因子和色度块对应的亮度重建信息，确定色度块的预测信息。这样，在编码或者解码时，选取出预设数目个色度值和预设数目个亮度值，然后划分成两个亮度集合和两个色度集合，基于各亮度集合中亮度值的均值和各色度集合中色度值的均值，确定出色度块的缩放系数，进而确定出偏移因子，并没有使用大量的乘法，所以可以节约编码时间和解码时间。
需要说明的是：上述实施例提供的色度块的预测装置在确定色度块的预测信息时，仅以上述各功能模块的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能模块完成，即将装置的内部结构划分成不同的功能模块，以完成以上描述的全部或者部分功能。另外，上述实施例提供的色度块的预测装置与色度块的预测方法实施例属于同一构思，其具体实现过程详见方法实施例，这里不再赘述。
本申请还提供了一种计算机可读存储介质，所述计算机可读存储介质存储有指令，当所述计算机可读存储介质在计算设备上运行时，使得所述计算设备执行上述色度块的预测方法。
本申请还提供了一种包含指令的计算机程序产品，当所述计算机程序产品在计算设备上运行时，使得所述计算设备执行上述色度块的预测方法。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现，当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令，在服务器或终端上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴光缆、光纤、数字用户线)或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是服务器或终端能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(如软盘、硬盘和磁带等)，也可以是光介质(如数字视盘(Digital Video Disk，DVD)等)，或者半导体介质(如固态硬盘等)。
以上所述仅为本申请的一个实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (28)

  1. 一种色度块的预测方法，其特征在于，所述方法包括：
    从色度块的相邻像素中，获取预设位置的色度像素的色度值；
    基于所述色度块对应的亮度块的相邻像素，获取所述预设位置的色度像素对应的亮度像素的亮度值；
    将获取到的亮度值分为第一亮度集合和第二亮度集合；
    将所述第一亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第一色度集合，并将所述第二亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第二色度集合；
    根据所述第一亮度集合中亮度值的均值、所述第二亮度集合中亮度值的均值、所述第一色度集合中色度值的均值和所述第二色度集合中色度值的均值，确定所述色度块对应的线性模型中的缩放系数；
    根据所述缩放系数，确定所述色度块对应的所述线性模型中的偏移因子；
    根据所述缩放系数、所述偏移因子和所述色度块对应的亮度重建信息，确定所述色度块的预测信息，其中，所述色度块对应的亮度重建信息包括所述色度块对应的亮度重建块的下采样信息。
  2. 根据权利要求1所述的方法，其特征在于，所述方法还包括：
    获取指示信息，基于所述指示信息确定所述色度块对应的帧内预测模式，其中，所述帧内预测模式包括线性模式LM、上侧线性模式LMA和左侧线性模式LML至少之一；
    根据所述色度块对应的帧内预测模式，确定所述预设位置。
  3. 根据权利要求1或2所述的方法，其特征在于，所述从色度块的相邻像素中，获取预设位置的色度像素的色度值，包括：
    根据预设的帧内预测模式和预设位置的对应关系，以及色度块对应的帧内预测模式，在所述色度块的相邻像素中，获取所述预设位置的色度像素的色度值。
  4. 根据权利要求1至3任一项所述的方法，其特征在于，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)和所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，其中，X表示所述色度块的宽度，Y表示所述色度块的高度；
    如果所述色度块对应的帧内预测模式为跨分量线性模式LM，则所述预设位置的色度像素的位置坐标为(0，-1)(X-1，-1)、(-1，0)、(-1，Y-1)。
  5. 根据权利要求4所述的方法，其特征在于，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)，其中，X表示所述色度块的宽度；
    如果所述色度块对应的帧内预测模式为跨分量上侧线性模式LMA，则所述预设位置的位置坐标为(0，-1)、(X/4，-1)、(X-1-X/4，-1)、(X-1，-1)，或者(0，-1)(X/4，-1)(3*X/4，-1)(X-1，-1)。
  6. 根据权利要求4或5所述的方法，其特征在于，所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，其中，Y表示所述色度块的高度；
    如果所述色度块对应的帧内预测模式为跨分量左侧线性模式LML，则所述预设位置的位置坐标为(-1，0)(-1，Y/4)(-1，Y-1-Y/4)(-1，Y-1)，或者(-1，0)(-1，Y/4)(-1，3*Y/4)(-1，Y-1)。
  7. 根据权利要求1至6任一项所述的方法，其特征在于，所述将获取到的亮度值分为第一亮度集合和第二亮度集合，包括：
    确定所述预设位置的色度像素对应的亮度像素的亮度值的均值；
    将所述预设位置的色度像素对应的亮度像素的亮度值中小于或等于所述亮度值的均值的亮度值组成第一亮度集合，并将所述预设位置的色度像素对应的亮度像素的亮度值中大于所述亮度值的均值的亮度值组成第二亮度集合。
  8. 根据权利要求1至6任一项所述的方法，其特征在于，所述将获取到的亮度值分为第一亮度集合和第二亮度集合，包括：
    将所述预设位置的色度像素对应的亮度像素的亮度值按照从小到大的顺序进行排列，得到第一亮度值队列；将所述第一亮度值队列中前半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中后半部分的亮度值组成所述第二亮度集合；或者，
    将所述预设位置的色度像素对应的亮度像素的亮度值按照从大到小的顺序进行排列，得到第二亮度值队列；将所述第二亮度值队列中后半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中前半部分的亮度值组成所述第二亮度集合。
  9. 根据权利要求1至8任一项所述的方法，其特征在于，所述根据所述第一亮度集合中亮度值的均值、所述第二亮度集合中亮度值的均值、所述第一色度集合中色度值的均值和所述第二色度集合中色度值的均值，确定所述色度块对应的线性模型中的缩放系数，包括：
    Figure PCTCN2019124399-appb-100001
    其中，α为所述色度块对应的线性模型中的缩放系数，C Lmean为所述第一色度集合中色度值的均值，C Rmean为所述第二色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值，L Rmean为所述第二亮度集合中亮度值的均值。
  10. 根据权利要求1至9任一项所述的方法，其特征在于，所述根据所述缩放系数，确定所述色度块对应的所述线性模型中的偏移因子，包括：
    根据所述缩放系数、所述第一色度集合中色度值的均值和所述第一亮度集合中亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子。
  11. 根据权利要求10所述的方法，其特征在于，所述根据所述缩放系数、所述第一色度集合中色度值的均值和所述第一亮度集合中亮度值的均值，确定所述色度块对应的线性模型中的偏移因子，包括：
    β＝C Lmean-α*L Lmean，其中，α为所述缩放系数，β为所述色度块对应的所述线性模型中的偏移因子，C Lmean为所述第一色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值。
  12. 根据权利要求1至9任一项所述的方法，其特征在于，所述根据所述缩放系数，确定所述色度块对应的所述线性模型中的偏移因子，包括：
    根据所述缩放系数、所述预设位置的色度像素的色度值的均值和所述色度像素对应的亮度像素的亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子。
  13. 根据权利要求12所述的方法，其特征在于，所述根据所述缩放系数、所述预设位置的色度像素的色度值的均值和所述色度像素对应的亮度像素的亮度值的均值，确定所述色度 块对应的所述线性模型中的偏移因子，包括：
    β＝C mean-α*L mean，其中，α为所述缩放系数，β为所述色度块对应的所述线性模型中的偏移因子，C mean为所述预设位置的色度像素的色度值的均值，L mean为所述预设位置的色度像素对应的亮度像素的亮度值的均值。
  14. 一种色度块的预测装置，其特征在于，所述装置包括：
    获取模块，用于从色度块的相邻像素中，获取预设位置的色度像素的色度值；基于所述色度块对应的亮度块的相邻像素，获取所述预设位置的色度像素对应的亮度像素的亮度值；
    划分模块，用于将获取到的亮度值分为第一亮度集合和第二亮度集合；将所述第一亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第一色度集合，并将所述第二亮度集合中的亮度值所属的亮度像素对应的色度像素的色度值，组成第二色度集合；
    确定模块，用于根据所述第一亮度集合中亮度值的均值、所述第二亮度集合中亮度值的均值、所述第一色度集合中色度值的均值和所述第二色度集合中色度值的均值，确定所述色度块对应的线性模型中的缩放系数；根据所述缩放系数，确定所述色度块对应的所述线性模型中的偏移因子；根据所述缩放系数、所述偏移因子和所述色度块对应的亮度重建信息，确定所述色度块的预测信息，其中，所述色度块对应的亮度重建信息包括所述色度块对应的亮度重建块的下采样信息。
  15. 根据权利要求14所述的装置，其特征在于，所述获取模块，还用于：
    获取指示信息，基于所述指示信息确定所述色度块对应的帧内预测模式，其中，所述帧内预测模式包括线性模式LM、上侧线性模式LMA和左侧线性模式LML至少之一；
    根据所述色度块对应的帧内预测模式，确定所述预设位置。
  16. 根据权利要求14或15所述的装置，其特征在于，所述获取模块，用于：
    根据预设的帧内预测模式和预设位置的对应关系，以及色度块对应的帧内预测模式，在所述色度块的相邻像素中，获取所述预设位置的色度像素的色度值。
  17. 根据权利要求14至16任一项所述的装置，其特征在于，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)和所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，其中，X表示所述色度块的宽度，Y表示所述色度块的高度；
    如果所述色度块对应的帧内预测模式为跨分量线性模式LM，则所述预设位置的色度像素的位置坐标为(0，-1)(X-1，-1)、(-1，0)、(-1，Y-1)。
  18. 根据权利要求17所述的装置，其特征在于，所述色度块的相邻上侧像素的位置坐标为(0，-1)，(1，-1)，……，(X-1，-1)，其中，X表示所述色度块的宽度；
    如果所述色度块对应的帧内预测模式为跨分量上侧线性模式LMA，则所述预设位置的位置坐标为(0，-1)、(X/4，-1)、(X-1-X/4，-1)、(X-1，-1)，或者(0，-1)(X/4，-1)(3*X/4，-1)(X-1，-1)。
  19. 根据权利要求17或18所述的装置，其特征在于，所述色度块的相邻左侧像素的位置坐标为(-1，0)，(-1，1)，……，(-1，Y-1)，其中，Y表示所述色度块的高度；
    如果所述色度块对应的帧内预测模式为跨分量左侧线性模式LML，则所述预设位置的位置坐标为(-1，0)(-1，Y/4)(-1，Y-1-Y/4)(-1，Y-1)，或者(-1，0)(-1，Y/4)(-1，3*Y/4) (-1，Y-1)。
  20. 根据权利要求14至19任一项所述的装置，其特征在于，所述划分模块，用于：
    确定所述预设位置的色度像素对应的亮度像素的亮度值的均值；
    将所述预设位置的色度像素对应的亮度像素的亮度值中小于或等于所述亮度值的均值的亮度值组成第一亮度集合，并将所述预设位置的色度像素对应的亮度像素的亮度值中大于所述亮度值的均值的亮度值组成第二亮度集合。
  21. 根据权利要求14至19任一项所述的装置，其特征在于，所述划分模块，用于：
    将所述预设位置的色度像素对应的亮度像素的亮度值按照从小到大的顺序进行排列，得到第一亮度值队列；如果所述第一亮度值队列中的亮度像素的个数是偶数，则将所述第一亮度值队列中前半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中后半部分的亮度值组成所述第二亮度集合；或者，
    将所述预设位置的色度像素对应的亮度像素的亮度值按照从大到小的顺序进行排列，得到第二亮度值队列；如果所述第二亮度值队列中的亮度像素的个数是偶数，则将所述第二亮度值队列中后半部分的亮度值组成所述第一亮度集合，并将所述亮度值队列中前半部分的亮度值组成所述第二亮度集合。
  22. 根据权利要求14至21任一项所述的装置，其特征在于，所述确定模块，用于：
    Figure PCTCN2019124399-appb-100002
    其中，α为所述色度块对应的线性模型中的缩放系数，C Lmean为所述第一色度集合中色度值的均值，C Rmean为所述第二色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值，L Rmean为所述第二亮度集合中亮度值的均值。
  23. 根据权利要求14至22任一项所述的装置，其特征在于，所述确定模块，用于：
    根据所述缩放系数、所述第一色度集合中色度值的均值和所述第一亮度集合中亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子。
  24. 根据权利要求23所述的装置，其特征在于，所述确定模块，用于：
    β＝C Lmean-α*L Lmean，其中，α为所述缩放系数，β为所述色度块对应的所述线性模型中的偏移因子，C Lmean为所述第一色度集合中色度值的均值，L Lmean为所述第一亮度集合中亮度值的均值。
  25. 根据权利要求14至22任一项所述的装置，其特征在于，所述确定模块，用于：
    根据所述缩放系数、所述预设位置的色度像素的色度值的均值和所述色度像素对应的亮度像素的亮度值的均值，确定所述色度块对应的所述线性模型中的偏移因子。
  26. 一种色度块的预测装置，其特征在于，所述预测装置包括存储器和处理器，其中，所述存储器用于存储所述处理器可执行指令；
    所述处理器，用于执行所述权利要求1-13中任一权利要求所述的色度块的预测方法。
  27. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储有指令，当所述计算机可读存储介质在计算设备上运行时，使得所述计算设备执行所述权利要求1-13中任一权利要求所述的色度块的预测方法。
  28. 一种包含指令的计算机程序产品，其特征在于，当所述计算机程序产品在计算设备上运行时，使得所述计算设备执行所述权利要求1-13中任一权利要求所述的色度块的预测方法。
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