WO2021185257A1 - 图像编码方法、图像解码方法及相关装置 - Google Patents

图像编码方法、图像解码方法及相关装置 Download PDF

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WO2021185257A1
WO2021185257A1 PCT/CN2021/081132 CN2021081132W WO2021185257A1 WO 2021185257 A1 WO2021185257 A1 WO 2021185257A1 CN 2021081132 W CN2021081132 W CN 2021081132W WO 2021185257 A1 WO2021185257 A1 WO 2021185257A1
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block
component
pixel
chrominance component
prediction
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French (fr)
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杨宁
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Oppo广东移动通信有限公司
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/186—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a colour or a chrominance component
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/117—Filters, e.g. for pre-processing or post-processing
    • 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
    • H04N19/124—Quantisation
    • 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
    • H04N19/13—Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
    • 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
    • H04N19/10—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
    • H04N19/146—Data rate or code amount at the encoder output
    • H04N19/147—Data rate or code amount at the encoder output according to rate distortion criteria
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
    • H04N19/91—Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Definitions

  • This application relates to the technical field of electronic equipment, and in particular to an image encoding method, an image decoding method, and related devices.
  • Digital video capabilities can be incorporated into a wide range of devices, including digital TVs, digital live broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, and e-books Readers, digital cameras, digital recording devices, digital media players, video game devices, video game consoles, cellular or satellite radio telephones, video conferencing devices, video streaming devices, etc.
  • PDAs personal digital assistants
  • laptop or desktop computers laptop or desktop computers
  • tablet computers and e-books Readers
  • digital cameras digital recording devices
  • digital media players digital media players
  • video game devices video game consoles
  • cellular or satellite radio telephones video conferencing devices
  • video streaming devices etc.
  • Digital video equipment implements video compression technology, such as MPEG-2, MPEG-4, ITU-TH.263, ITU-TH.264/MPEG-4 Part 10 advanced video coding (advanced video coding, AVC), ITU- The TH.265 high efficiency video coding (HEVC) standard defines the standard and those video compression techniques described in the extension of the standard, so as to transmit and receive digital video information more efficiently.
  • Video devices can transmit, receive, encode, decode, and/or store digital video information more efficiently by implementing these video codec technologies.
  • the embodiments of the present application provide an image encoding method, an image decoding method, and related devices, so as to use different filters for downsampling according to different directivities of the current coding unit in the cross-component prediction mode.
  • an embodiment of the present application provides an image encoding method, including: dividing an image, determining the luma component intra prediction mode and the chroma component intra prediction mode of the current encoding block; when the chroma component intra prediction mode When instructing to use the luminance component of the current coding block to derive the chrominance component of the current coding block, determine the reference prediction block of the chrominance component of the current coding block according to the intra prediction mode of the luminance component; The reference prediction block of the chrominance component of the current coding block is filtered to obtain the prediction block of the chrominance component of the current coding block.
  • the solution of the present application uses the cross-component prediction mode to filter the reference prediction block of the chrominance component of the current coding block, which is beneficial to improve the compression efficiency of the coding block, thereby improving the coding efficiency.
  • an embodiment of the present application provides an image decoding method, including: parsing a code stream to determine the luma component intra prediction mode and chroma component intra prediction mode of the current decoded block; when the chroma component intra prediction The mode indicates that when the reconstructed block of the luminance component of the currently decoded block is used to derive the predicted value of the chrominance component of the currently decoded block, the chrominance component of the current decoded block is determined according to the luminance component intra prediction mode The reference prediction block; filtering the reference prediction block of the chrominance component of the currently decoded block to obtain the prediction block of the chrominance component of the currently decoded block.
  • the solution of the present application implements filtering of the reference prediction block of the chrominance component of the current decoded block in the cross-component prediction mode, which is beneficial to improve the compression efficiency of the decoded block, thereby improving the decoding efficiency.
  • an embodiment of the present application provides an image encoding device, including: a dividing unit for dividing an image, and determining a luma component intra prediction mode and a chroma component intra prediction mode of the current coding block; and a determining unit for When the chrominance component intra prediction mode indicates to use the luminance component of the current coding block to derive the chrominance component of the current coding block, determine the color of the current coding block according to the luminance component intra prediction mode The reference prediction block of the degree component; a filtering unit, configured to filter the reference prediction block of the chrominance component of the current coding block to obtain the prediction block of the chrominance component of the current coding block.
  • an embodiment of the present application provides an image decoding device, including: a parsing unit for parsing a code stream to determine the luma component intra prediction mode and chroma component intra prediction mode of the current decoded block; the determining unit uses When the chrominance component intra prediction mode indicates to use the reconstructed block of the luma component of the currently decoded block to derive the prediction value of the chroma component of the current decoded block, according to the luma component intra prediction mode, Determine the reference prediction block of the chrominance component of the currently decoded block; a filtering unit for filtering the reference prediction block of the chrominance component of the currently decoded block to obtain the chrominance component prediction block of the currently decoded block .
  • an embodiment of the present application provides an encoder, including: a processor and a memory coupled to the processor; the processor is configured to execute the method described in the first aspect.
  • an embodiment of the present application provides a decoder, including: a processor and a memory coupled to the processor; the processor is configured to execute the method described in the second aspect.
  • an embodiment of the present application provides a terminal, the terminal including: one or more processors, a memory, and a communication interface; the memory and the communication interface are connected to the one or more processors; The terminal communicates with other devices through the communication interface, the memory is used to store computer program code, the computer program code includes instructions, when the one or more processors execute the instructions, the terminal executes The method as described in the first or second aspect.
  • an embodiment of the present application provides a computer-readable storage medium that stores instructions in the computer-readable storage medium.
  • the instructions run on a computer, the computer executes the first aspect or the second aspect described above. The method described in the aspect.
  • the embodiments of the present application provide a computer program product containing instructions that, when the instructions are run on a computer, cause the computer to execute the method described in the first aspect or the second aspect.
  • FIG. 1 is a schematic block diagram of a coding tree unit in an embodiment of this application
  • Figure 2 is a schematic block diagram of a color format in an embodiment of the application
  • FIG. 3 is a schematic block diagram of a CTU and a coding unit CU in an embodiment of this application;
  • FIG. 4 is a schematic block diagram of associated pixels of a coding unit in an embodiment of the application.
  • FIG. 5 is a schematic block diagram of a luminance component intra prediction mode in an embodiment of the application.
  • FIG. 6 is a schematic block diagram of adjacent pixels used for calculation of coefficients of a linear model in an embodiment of the application
  • FIG. 7 is a schematic block diagram of a downsampling filter in an embodiment of this application.
  • FIG. 8 is a schematic block diagram of a change from a luminance component reconstruction block to a chrominance component prediction block in an embodiment of the application;
  • FIG. 9 is a schematic block diagram of a video decoding system in an embodiment of this application.
  • FIG. 10 is a schematic block diagram of a video encoder in an embodiment of the application.
  • FIG. 11 is a schematic block diagram of a video decoder in an embodiment of this application.
  • FIG. 12A is a schematic flowchart of an image coding method in an embodiment of this application.
  • FIG. 12B is a schematic diagram of a down-sampling process in a horizontal direction in an embodiment of this application.
  • FIG. 12C is a schematic diagram of a down-sampling process in a vertical direction in an embodiment of the application.
  • FIG. 12D is a schematic diagram of a down-sampling process in a diagonal direction in an embodiment of this application.
  • FIG. 13 is a schematic flowchart of an image decoding method in an embodiment of this application.
  • FIG. 14 is a block diagram of a functional unit of an image encoding device in an embodiment of the application.
  • 15 is a block diagram of another functional unit of the image encoding device in an embodiment of the application.
  • 16 is a block diagram of a functional unit of the image decoding device in an embodiment of the application.
  • Fig. 17 is a block diagram of another functional unit of the image decoding device in an embodiment of the application.
  • first, second, etc. used in the present invention can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.
  • first client may be referred to as the second client, and similarly, the second client may be referred to as the first client. Both the first client and the second client are clients, but they are not the same client.
  • CTU coding tree unit
  • CU coding unit
  • PU Prediction Unit
  • TU Transform Unit
  • Coding tree unit CTU an image is composed of multiple CTUs, a CTU usually corresponds to a square image area, including the luminance pixels and chrominance pixels in this image area (or only luminance pixels, or only Chroma pixels);
  • the CTU also contains syntax elements, which indicate how to divide the CTU into at least one coding unit (CU), and a method for decoding each coding unit to obtain a reconstructed image.
  • the image 10 is composed of multiple CTUs (including CTU A, CTU B, CTU C, etc.).
  • the coding information corresponding to a certain CTU includes the luminance value and/or chrominance value of the pixel in the square image area corresponding to the CTU.
  • the coding information corresponding to a certain CTU may also include syntax elements, which indicate how to divide the CTU into at least one CU, and a method for decoding each CU to obtain a reconstructed image.
  • the image area corresponding to a CTU may include 64 ⁇ 64, 128 ⁇ 128, or 256 ⁇ 256 pixels.
  • a CTU of 64 ⁇ 64 pixels includes a rectangular pixel dot matrix with 64 columns and 64 pixels in each column, and each pixel includes a luminance component and/or a chrominance component.
  • a CTU can also correspond to a rectangular image area or an image area of other shapes.
  • the image area corresponding to a CTU can also be an image area in which the number of pixels in the horizontal direction is different from the number of pixels in the vertical direction, for example, it includes 64 ⁇ 128 pixels. .
  • the coding unit CU usually corresponds to an A ⁇ B rectangular area in the image, containing A ⁇ B luminance pixels or/and its corresponding chrominance pixels, A is the width of the rectangle, B is the height of the rectangle, and A and B can be the same It can also be different.
  • the values of A and B are usually integer powers of 2, such as 128, 64, 32, 16, 8, 4.
  • the width involved in the embodiments of the present application refers to the length along the X-axis direction (horizontal direction) in the two-dimensional rectangular coordinate system XoY shown in FIG. 1, and the height refers to the two-dimensional rectangular coordinate system XoY shown in FIG. The length along the Y axis (vertical direction).
  • the reconstructed image of a CU can be obtained by adding the predicted image and the residual image.
  • the predicted image is generated by intra-frame prediction or inter-frame prediction. Specifically, it can be composed of one or more prediction blocks (PB).
  • the inverse quantization and inverse transform processing of the transform coefficients are generated, which may be specifically composed of one or more transform blocks (TB).
  • a CU contains coding information, and the coding information includes prediction mode, transform coefficients and other information. According to the coding information, corresponding prediction, inverse quantization, inverse transform and other decoding processing are performed on the CU to generate a reconstructed image corresponding to this CU.
  • the prediction unit PU is the basic unit of intra prediction and inter prediction.
  • the motion information that defines the image block includes inter-frame prediction direction, reference frame, motion vector, etc.
  • the image block that is being encoded is called the current coding block (CCB), and the image block that is being decoded is called the current decoding.
  • Block (current decoding block, CDB) for example, when an image block is undergoing prediction processing, the current encoding block or the current decoding block is the prediction block; when an image block is undergoing residual processing, the current encoding block or the current decoding block is Transform the block.
  • the image where the current coding block or the current decoding block is located is called the current frame.
  • the image blocks located on the left or upper side of the current block may be inside the current frame and have completed the encoding/decoding process to obtain a reconstructed image. They are called reconstructed blocks; the encoding mode of the reconstructed block, the reconstructed pixels, etc. Information is available (available). Frames that have been encoded/decoded before the current frame is encoded/decoded are called reconstructed frames.
  • the current frame is a unidirectional predictive frame (P frame) or a bidirectional predictive frame (B frame)
  • it has one or two reference frame lists.
  • the two lists are called L0 and L1, and each list contains at least one reconstruction Frame, called the reference frame of the current frame.
  • the reference frame provides reference pixels for the inter-frame prediction of the current frame.
  • the transformation unit TU processes the residuals of the original image block and the predicted image block.
  • Pixel also called pixel point refers to the pixel point in the image, such as the pixel point in the coding unit, the pixel point in the luminance component pixel block (also known as the luminance pixel), the pixel point in the chrominance component pixel block (Also called chrominance pixels) and so on.
  • Sample refers to the pixel value of a pixel.
  • the pixel value specifically refers to the brightness (ie grayscale value) in the luminance component domain
  • the pixel value specifically refers to the chrominance value in the chrominance component domain. (I.e. color and saturation), according to different processing stages, a pixel sample specifically includes an original sample, a predicted sample, and a reconstructed sample.
  • Intra-frame prediction based on the spatial neighboring pixels of the current block, generates a predicted image of the current block.
  • An intra-frame prediction mode corresponds to a method of generating a predicted image.
  • the division of intra prediction units includes 2N ⁇ 2N division (as shown in A in Figure 2) and N ⁇ N division (as shown in B in Figure 2).
  • the 2N ⁇ 2N division is not performed on image blocks.
  • Division: The N ⁇ N division method is to divide the image block into four sub-image blocks of equal size.
  • Y represents the brightness (Luminance or Luma), which is the grayscale value
  • Cb represents the blue chroma component
  • Cr represents the red chroma component
  • U and V represent the chroma (Chrominance or Chroma), used to describe the color and saturation Spend.
  • 4:2:0 means that every 4 pixels have 4 luminance components
  • 2 chrominance components YYYYCbCr
  • 4:2:2 means that every 4 pixels have 4 luminance components
  • 4 chrominance Component YYYYCbCrCbCr
  • 4:4:4 means full-pixel display (YYYYCbCrCbCrCbCr).
  • Figure 2 shows the distribution of each component in different color formats. The circle is the Y component and the triangle is the UV component.
  • the encoder reads pixels and encodes the original video sequence in different color formats.
  • digital encoders usually include prediction, transformation and quantization, inverse transformation and inverse quantization, loop filtering, and entropy coding, etc., which are used to eliminate space, time, vision, and character redundancy.
  • human eyes are more sensitive to changes in luminance components, and do not respond strongly to changes in chrominance components. Therefore, YUV 4:2:0 color format is generally used for encoding in original video sequences.
  • the digital video encoder adopts different prediction processes for the luminance component and the chrominance component in the intra-frame coding part.
  • the prediction of the luminance component is more detailed and complicated, while the prediction of the chrominance component is usually relatively simple.
  • the Cross Component Prediction (CCP) mode is a technology that acts on the luminance component and the chrominance component in the existing digital video coding to improve the video compression ratio.
  • the specific implementation process of the cross-component prediction mode is applied to the intra-frame coding.
  • the method includes using the training samples of the Luminance Block to determine the Linear Model for predicting the Chrominance Block, and using the Luminance Block.
  • the sample of the block and the linear model are used to determine the sample of the chroma block.
  • the luminance block and the chrominance block are the pixel blocks in the luminance component and the chrominance component of the coding unit.
  • the digital video encoder usually reads the original video sequence into a frame by frame image and divides the image into a coding tree unit CTU , And the coding tree unit can continue to be divided into coding units CU of different and the same size.
  • the specific coding process is carried out in coding units of different components. The relationship between coding tree units and coding units is shown in FIG. 3.
  • CCP cross-component prediction
  • VVC Versatile Video Coding
  • CCLM cross-component linear model
  • Fig. 4 respectively shows an example of the positional relationship between an original pixel block of 8x8 luminance component and neighboring pixels, and an original predicted pixel block of 4x4 chrominance component and neighboring pixels under the color format YUV4:2:0.
  • the prediction samples of the pixels in the chrominance component prediction block are obtained by linear model calculation and down-sampling from the reconstructed samples of the pixels in the original pixel block of the luminance component of the current coding unit, where the linear model calculation process represents as follows:
  • (i, j) are the coordinates of the pixel, and x specifically refers to the abscissa of the prediction block of the chrominance component of the current coding unit, and its range is [0, width-1], the step size is 1, and width is the current encoding
  • the width of the prediction block of the chroma component of the unit can be 4, 8, 16, and 32; y specifically refers to the ordinate of the prediction block of the chroma component of the current coding unit, and its range is [0, height- 1], the step size is 1, the height is the height of the prediction block of the chrominance component of the current coding unit, and its value can be 4, 8, 16 and 32, and Rec L is the weight of the pixel in the original pixel block of the luminance component. Rec L is the prediction sample of the pixel in the prediction block of the chrominance component, and ⁇ and ⁇ are the coefficients of the linear model.
  • the latest cross-component technology proposal M4612 adopted by China's Digital Audio Video Coding Standard (AVS), two-step cross-component prediction mode (TSCPM) is calculated for up to 65 intra-prediction modes (Intra Prediction mode), DC stands for mean mode, Plane stands for planar mode, Bilinear stands for bilinear mode, Zone stands for zone . According to the rate distortion (Rate Distortion) cost, the optimal result is selected and the intra prediction mode and the corresponding prediction residual are transmitted.
  • Intra Prediction mode DC stands for mean mode
  • Plane stands for planar mode
  • Bilinear stands for bilinear mode
  • Zone stands for zone .
  • the optimal result is selected and the intra prediction mode and the corresponding prediction residual are transmitted.
  • the reconstructed samples of the neighboring pixels of the original pixel block of the luminance component of the current coding unit and the phase of the original prediction pixel block of the chrominance component of the current coding unit are used in the calculation of the linear model.
  • the adjacent pixels of the original pixel block of the luminance component include the upper adjacent pixel and the left adjacent pixel of the original pixel block of the luminance component of the current coding unit; the adjacent pixels of the prediction block of the chrominance component include the current The upper neighboring pixel and the left neighboring pixel of the prediction block of the coding unit chrominance component.
  • the reconstructed sample When the reconstructed sample is selected as the reference sample for calculating the coefficients of the linear model, combined with the availability of the reconstructed sample of adjacent pixels, the reconstructed sample of two pixels in the upper adjacent pixel and two of the adjacent pixels on the left can be used.
  • the combination of the reconstructed samples of each pixel may also use all the reconstructed samples of the four pixels in the upper adjacent pixels, and all the reconstructed samples of the four pixels in the left adjacent pixels.
  • the prediction mode includes, if the original pixel block of the luminance component and the original pixel block of the chrominance component corresponding to the current coding unit (referred to as the original pixel block for the convenience of description), the upper adjacent pixel When the reconstructed samples of the current coding unit and the reconstructed samples of the adjacent pixels on the left of the original pixel block of the current coding unit are available, and the reference samples used in the coefficient calculation of the linear model are both from the upper and left adjacent pixels, or if the current When the original pixel block corresponding to the coding unit has only the reconstructed samples of the upper neighboring pixels available, and the reference sample used in the calculation of linear model coefficients is only the reconstructed sample of the upper neighboring pixel, or if the original pixel corresponding to the current coding unit Only the reconstructed samples of the neighboring pixels on the left of the block are available, and the reference samples used in the calculation of the coefficients of the linear model are only the reconstructed samples
  • the reconstructed sample of the pixel is in TSCPM_T mode; if the reconstructed sample of the upper neighboring pixel of the original pixel block corresponding to the current coding unit and the reconstructed sample of the left neighboring pixel of the original pixel block corresponding to the current coding unit are available , And when the reference sample used in the calculation of the coefficients of the linear model is only the reconstructed sample of the upper adjacent pixel, it is the TSCPM_L mode.
  • the upper reference sample is selected as the upper
  • the reconstructed sample of the leftmost pixel among adjacent pixels is the reconstructed sample of the rightmost pixel above the width of the original pixel block corresponding to the current coding unit block.
  • the distance of a quarter of the width of the original pixel block corresponding to the unit is the step size, and the reconstructed samples of the four consecutive step size pixels among the adjacent pixels on the upper side are selected; if the reference sample is only from the left side, the current code is used.
  • the distance of a quarter of the height of the original pixel block corresponding to the unit is the step size, and the reconstructed samples of the four consecutive step size pixels among the four left adjacent pixels are selected.
  • Y Max is the average value of the two largest reconstructed samples among the reconstructed samples of multiple adjacent pixel points of the original pixel block of the original pixel block of the chrominance component used for the calculation of the coefficients of the linear model
  • Y Min is the average value of the two largest reconstructed samples used for the linear model
  • the calculated coefficient of the chrominance component is the average value of the two smallest reconstructed samples among the reconstructed samples of multiple adjacent pixel points of the original pixel block.
  • X Max is the average value of the two largest reconstructed samples among the reconstructed samples of the multiple adjacent pixel points of the original pixel block of the luminance component used for the calculation of the coefficient of the linear model
  • X Min is the coefficient used for the linear model
  • the calculated brightness component is the average value of the two smallest reconstructed samples among the reconstructed samples of multiple adjacent pixel points of the original pixel block.
  • the current CU's luminance component reconstruction block is used to generate the corresponding chroma component reference prediction block (Chroma Reference Prediction Pixel Block).
  • the reference prediction sample of the chrominance component of each pixel of the current coding unit is calculated according to equations (1), (2) and (3).
  • the chrominance component refers to the size of the prediction block and the size of the original pixel block of the luminance component. same.
  • the input digital video color format is generally YUV 4:2:0 format, that is, the size of the chrominance component prediction block is one-fourth of the original pixel block of the luminance component.
  • the chrominance component reference prediction block In order to obtain the corresponding chrominance component prediction block of the correct size, the chrominance component reference prediction block needs to be down-sampled by half in the horizontal and vertical directions respectively, and the chrominance component prediction block after the down-sampling is the corresponding luminance A quarter of the original pixel block of the component meets the size requirement of the color format constraint.
  • the filter used for down-sampling the chrominance component reference prediction block uses two-tap down-sampling filters with the same coefficient in the left boundary pixel area of the chrominance component reference prediction block, while six-tap filters are used in other pixel areas. Tap down sampling filter with two different coefficients.
  • FIG. 7 shows a schematic diagram of the cross-component technology from the luminance component reconstruction block to the chrominance component prediction block.
  • the size of the luminance component reconstruction block of the coding unit is 8*8, and the size of the corresponding chrominance component reference prediction block is 8*8, the size of the filtered chrominance component prediction block is 4*4.
  • natural video contains feature information of various angles and directions.
  • the original pixel block of the brightness component of the image can be calculated according to the intra-prediction mode of multiple angles, and the best one can be selected. Excellent intra-frame prediction mode to get better angle prediction effect and improve compression efficiency.
  • the existing image coding and decoding technology uses the luminance component predicted by the current coding unit to reconstruct the block, and performs linear transformation to obtain the chrominance component reference prediction block of the current coding unit.
  • the chrominance component reference prediction block contains more characteristic information of the luminance component. Such as directional characteristics.
  • the downsampling method of using a single fixed filter to downsample the temporary chrominance component prediction block does not take into account some prominent feature information of the current video content, and all the content is uniformly blurred. This uses a single fixed filter
  • the down-sampling method reduces the intensity of various directional information of chrominance components and reduces the efficiency of video compression.
  • this application proposes the following design ideas.
  • the intra prediction process of the luminance component and the chrominance component is quite different, and the luminance component performs a maximum of 62 angular prediction modes and 3 non-angle predictions.
  • the mode is calculated and an optimal intra prediction mode is selected for transmission, and the intra prediction mode of the chrominance component is calculated for up to 6 prediction modes, and the intra prediction process of the luminance component is more accurate.
  • the luminance component and the chrominance component have feature consistency, that is, the main feature information of the image content remains consistent in different components and does not change due to linear transformation.
  • the reference prediction block of the chrominance component after linear transformation of the reconstruction block of the luminance component should still contain the main feature information of the coding unit If the prediction of the chrominance component can maintain the main characteristic information in the optimal mode of the corresponding luminance component, the compression efficiency of the coding unit can be improved. Therefore, the technical solution of the present application considers the optimal mode of the intra-angle prediction of the luminance component of the current coding unit as the guide information, and separately designs the down-sampling filter of the reference prediction block of the chrominance component.
  • FIG. 9 is a block diagram of an example video decoding system 1 described in the embodiments of this application.
  • the term "video decoder” generally refers to both video encoders and video decoders.
  • the term “video coding” or “coding” may generally refer to video encoding or video decoding.
  • the video encoder 100 and the video decoder 200 of the video coding system 1 are used for the cross-component prediction method proposed in this application in real time.
  • the video coding system 1 includes a source device 10 and a destination device 20.
  • Source device 10 generates encoded video data. Therefore, the source device 10 may be referred to as a video encoding device.
  • Destination device 20 may decode the encoded video data generated by source device 10. Therefore, the destination device 20 may be referred to as a video decoding device.
  • Various implementations of source device 10, destination device 20, or both may include one or more processors and a memory coupled to the one or more processors.
  • the memory may include, but is not limited to, RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store the desired program code in the form of instructions or data structures that can be accessed by a computer, as described herein.
  • the source device 10 and the destination device 20 may include various devices, including desktop computers, mobile computing devices, notebook (for example, laptop) computers, tablet computers, set-top boxes, telephone handsets such as so-called “smart" phones.
  • desktop computers mobile computing devices
  • notebook (for example, laptop) computers tablet computers
  • set-top boxes telephone handsets such as so-called “smart” phones.
  • Computer television, camera, display device, digital media player, video game console, on-board computer or the like.
  • Link 30 may include one or more media or devices capable of moving encoded video data from source device 10 to destination device 20.
  • link 30 may include one or more communication media that enable source device 10 to transmit encoded video data directly to destination device 20 in real time.
  • the source device 10 may modulate the encoded video data according to a communication standard, such as a wireless communication protocol, and may transmit the modulated video data to the destination device 20.
  • the one or more communication media may include wireless and/or wired communication media, such as a radio frequency (RF) spectrum or one or more physical transmission lines.
  • RF radio frequency
  • the one or more communication media may form part of a packet-based network, such as a local area network, a wide area network, or a global network (e.g., the Internet).
  • the one or more communication media may include routers, switches, base stations, or other devices that facilitate communication from source device 10 to destination device 20.
  • the encoded data may be output from the output interface 140 to the storage device 40.
  • the image coding and decoding technology of this application can be applied to video coding and decoding to support a variety of multimedia applications, such as aerial TV broadcasting, cable TV transmission, satellite TV transmission, streaming video transmission (for example, via the Internet), for storage in data storage Encoding of video data on the media, decoding of video data stored on the data storage media, or other applications.
  • the video coding system 1 may be used to support one-way or two-way video transmission to support applications such as video streaming, video playback, video broadcasting, and/or video telephony.
  • the video coding system 1 illustrated in FIG. 9 is only an example, and the technology of the present application is applicable to video coding settings (for example, video coding or video decoding) that do not necessarily include any data communication between the coding device and the decoding device. .
  • the data is retrieved from local storage, streamed on the network, and so on.
  • the video encoding device may encode 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 the memory and decode the data.
  • the source device 10 includes a video source 120, a video encoder 100 and an output interface 140.
  • the output interface 140 may include a regulator/demodulator (modem) and/or a transmitter.
  • the video source 120 may include a video capture device (for example, a camera), a video archive containing previously captured video data, a video feed interface to receive video data from a video content provider, and/or a computer for generating video data Graphics system, or a combination of these sources of video data.
  • the video encoder 100 may encode video data from the video source 120.
  • source device 10 transmits the encoded video data directly to destination device 20 via output interface 140.
  • the encoded video data may also be stored on the storage device 40 for later access by the destination device 20 for decoding and/or playback.
  • the destination device 20 includes an input interface 240, a video decoder 200 and a display device 220.
  • the input interface 240 includes a receiver and/or a modem.
  • the input interface 240 may receive encoded video data via the link 30 and/or from the storage device 40.
  • the display device 220 may be integrated with the destination device 20 or may be external to the destination device 20. Generally, the display device 220 displays the decoded video data.
  • the display device 220 may include various display devices, for example, a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or other types of display devices.
  • LCD liquid crystal display
  • OLED organic light emitting diode
  • the video encoder 100 and the video decoder 200 may be integrated with the audio encoder and decoder, respectively, and may include an appropriate multiplexer-demultiplexer unit Or other hardware and software to handle the encoding of both audio and video in a common data stream or separate data streams.
  • the MUX-DEMUX unit may conform to the ITU H.223 multiplexer protocol, or other protocols such as the user datagram protocol (UDP).
  • Each of the video encoder 100 and the video decoder 200 may be implemented as any of a variety of circuits such as: one or more microprocessors, digital signal processors (DSP), application specific integrated circuits (ASIC), Field programmable gate array (FPGA), discrete logic, hardware, or any combination thereof.
  • DSP digital signal processors
  • ASIC application specific integrated circuits
  • FPGA Field programmable gate array
  • the device may store instructions for the software in a suitable non-volatile computer-readable storage medium, and may use one or more processors to execute the instructions in hardware So as to implement the technology of this application. Any of the foregoing (including hardware, software, a combination of hardware and software, etc.) can be regarded as one or more processors.
  • Each of the video encoder 100 and the video decoder 200 may be included in one or more encoders or decoders, and any of the encoders or decoders may be integrated as a combined encoder in the corresponding device / Part of the decoder (codec).
  • FIG. 10 is an exemplary block diagram of a video encoder 100 described in an embodiment of this application.
  • the video encoder 100 is used to output the video to the post-processing entity 41.
  • the post-processing entity 41 represents an example of a video entity that can process the encoded video data from the video encoder 100, such as a media-aware network element (MANE) or a splicing/editing device.
  • the post-processing entity 41 may be an instance of a network entity.
  • the post-processing entity 41 and the video encoder 100 may be parts of separate devices, while in other cases, the functionality described with respect to the post-processing entity 41 may be the same device including the video encoder 100 implement.
  • the post-processing entity 41 is an example of the storage device 40 in FIG. 1.
  • the video encoder 100 includes a prediction processing unit 108, a filter unit 106, a decoded image buffer (DPB) 107, a summer 112, a transformer 101, a quantizer 102, and an entropy encoder 103.
  • the prediction processing unit 108 includes an inter predictor 110 and an intra predictor 109.
  • the video encoder 100 further includes an inverse quantizer 104, an inverse transformer 105, and a summer 111.
  • the filter unit 106 represents one or more loop filters, such as a deblocking filter, an adaptive loop filter (ALF), and a sample adaptive offset (SAO) filter.
  • ALF adaptive loop filter
  • SAO sample adaptive offset
  • the filter unit 106 is shown as an in-loop filter in FIG. 10, in other implementations, the filter unit 106 may be implemented as a post-loop filter.
  • the video encoder 100 may further include a video data storage and a dividing unit (not shown in the figure).
  • the video encoder 100 receives video data and stores the video data in a video data storage.
  • the dividing unit divides the video data into several image blocks, and these image blocks can be further divided into smaller blocks, such as image block division based on a quad-tree structure or a binary tree structure.
  • the prediction processing unit 108 may select one of multiple possible coding modes for the current image block, such as one of multiple intra coding modes or one of multiple inter coding modes.
  • the prediction processing unit 108 may provide the resulting intra- and inter-coded blocks to the summer 112 to generate a residual block, and to the summer 111 to reconstruct the encoded block used as a reference image.
  • the intra predictor 109 in the prediction processing unit 108 may perform intra predictive coding of the current image block with respect to one or more neighboring blocks in the same frame or slice as the current block to be coded to remove spatial redundancy .
  • the inter predictor 110 in the prediction processing unit 108 may perform inter predictive encoding of the current image block with respect to one or more prediction blocks in one or more reference images to remove temporal redundancy.
  • the prediction processing unit 108 provides information indicating the selected intra or inter prediction mode of the current image block to the entropy encoder 103 so that the entropy encoder 103 encodes the information indicating the selected inter prediction mode.
  • the video encoder 100 forms a residual image block by subtracting the prediction block from the current image block to be encoded.
  • Summer 112 represents one or more components that perform this subtraction operation.
  • the residual video data in the residual block may be included in one or more TUs and applied to the transformer 101.
  • the transformer 101 transforms residual video data into residual transform coefficients using transforms such as discrete cosine transform (DCT) or conceptually similar transforms.
  • DCT discrete cosine transform
  • the transformer 101 can transform the residual video data from the pixel value domain to the transform domain, such as the frequency domain.
  • the transformer 101 may send the resulting transform coefficient to the quantizer 102.
  • the quantizer 102 quantizes the transform coefficient to further reduce the bit rate.
  • the quantizer 102 may then perform a scan of the matrix containing the quantized transform coefficients.
  • the entropy encoder 103 may perform scanning.
  • the entropy encoder 103 After the quantization, the entropy encoder 103 performs entropy encoding on the quantized transform coefficient. For example, the entropy encoder 103 can perform context adaptive variable length coding (CAVLC), context adaptive binary arithmetic coding (CABAC), grammar-based context adaptive binary arithmetic coding (SBAC), and probability interval segmentation entropy (PIPE). ) Coding or another entropy coding method or technique. After being entropy-encoded by the entropy encoder 103, the encoded bitstream may be transmitted to the video decoder 200, or archived for later transmission or retrieval by the video decoder 200. The entropy encoder 103 may also perform entropy encoding on the syntax elements of the current image block to be encoded.
  • CAVLC context adaptive variable length coding
  • CABAC context adaptive binary arithmetic coding
  • SBAC grammar-based context adaptive binary arithmetic coding
  • the inverse quantizer 104 and the inverse transformer 105 respectively apply inverse quantization and inverse transformation to reconstruct the residual block in the pixel domain, for example, for later use as a reference block of a reference image.
  • the summer 111 adds the reconstructed residual block to the prediction block generated by the inter predictor 110 or the intra predictor 109 to generate a reconstructed image block.
  • the filter unit 106 may be applied to reconstructed image blocks to reduce distortion, such as block artifacts. Then, the reconstructed image block is stored as a reference block in the decoded image buffer 107, which can be used as a reference block by the inter predictor 110 to perform inter prediction of a block in a subsequent video frame or image.
  • the intra-frame predictor 109 may perform intra-frame prediction on the current coding unit, and specifically implement the image coding method provided in the embodiment of the present application.
  • the intra predictor 109 may also provide information indicating the selected intra prediction mode of the current coding unit to the entropy encoder 103 so that the entropy encoder 103 encodes the information indicating the selected intra prediction mode.
  • FIG. 11 is an exemplary block diagram of a video decoder 200 described in an embodiment of this application.
  • the video decoder 200 includes an entropy decoder 203, a prediction processing unit 208, an inverse quantizer 204, an inverse transformer 205, a summer 211, a filter unit 206, and a decoded image buffer 207.
  • the prediction processing unit 208 may include an inter predictor 210 and an intra predictor 209.
  • video decoder 200 may perform a decoding process that is generally reciprocal of the encoding process described with respect to video encoder 100 from FIG. 10.
  • the video decoder 200 receives from the video encoder 100 an encoded video code stream representing image blocks of an encoded video slice and associated syntax elements.
  • the video decoder 200 may receive video data from the network entity 42, and optionally, may also store the video data in a video data storage (not shown in the figure).
  • the video data storage may store video data to be decoded by the components of the video decoder 200, such as an encoded video stream.
  • the video data stored in the video data storage can be obtained, for example, from the storage device 40, from a local video source such as a camera, via wired or wireless network communication of the video data, or by accessing a physical data storage medium.
  • the video data memory can be used as a decoded picture buffer (CPB) for storing encoded video data from an encoded video stream.
  • CPB decoded picture buffer
  • the network entity 42 may be, for example, a server, a MANE, a video editor/splicer, or other such device for implementing one or more of the techniques described above.
  • the network entity 42 may or may not include a video encoder, such as the video encoder 100.
  • the network entity 42 may implement part of the technology described in this application.
  • the network entity 42 and the video decoder 200 may be part of separate devices, while in other cases, the functionality described with respect to the network entity 42 may be performed by the same device including the video decoder 200.
  • the entropy decoder 203 of the video decoder 200 entropy decodes the code stream to generate quantized coefficients and some syntax elements.
  • the entropy decoder 203 forwards the syntax element to the prediction processing unit 208.
  • the video decoder 200 may receive syntax elements at the video slice level and/or the image block level.
  • the intra-predictor 209 of the prediction processing unit 208 is based on the signaled intra-prediction mode and the data from the previous decoded block of the current frame or image The prediction block of the image block of the current video slice is generated.
  • the inter predictor 210 of the prediction processing unit 208 may determine the current In the inter-frame prediction mode in which the current image block of the video slice is decoded, the current image block is decoded based on the determined inter-frame prediction mode (for example, inter-frame prediction is performed).
  • the inverse quantizer 204 inversely quantizes, ie, dequantizes, the quantized transform coefficients provided in the bitstream and decoded by the entropy decoder 203.
  • the inverse quantization process may include using the quantization parameter calculated by the video encoder 100 for each image block in the video slice to determine the degree of quantization that should be applied and likewise determine the degree of inverse quantization that should be applied.
  • the inverse transformer 205 applies an inverse transform to the transform coefficients, such as an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process, in order to generate a residual block in the pixel domain.
  • the video decoder 200 compares the residual block from the inverse transformer 205 with the corresponding prediction generated by the inter predictor 210.
  • the blocks are summed to obtain a reconstructed block, that is, a decoded image block.
  • the summer 211 represents the component that performs this summation operation.
  • loop filters either in the decoding loop or after the decoding loop
  • the filter unit 206 may represent one or more loop filters, such as a deblocking filter, an adaptive loop filter (ALF), and a sample adaptive offset (SAO) filter.
  • ALF adaptive loop filter
  • SAO sample adaptive offset
  • the video decoder 200 may generate an output video stream without processing by the filter unit 206; or, for some image blocks or image frames, the entropy decoder 203 of the video decoder 200 does not decode the quantized coefficients, and accordingly It does not need to be processed by the inverse quantizer 204 and the inverse transformer 205.
  • the intra-frame predictor 209 may use the image decoding method described in the embodiment of the present application in the process of generating the prediction block.
  • FIG. 12A is a schematic flowchart of an image encoding method in an embodiment of the application.
  • the image encoding method can be applied to the source device 10 in the video decoding system 1 shown in FIG. 9 or the video encoder 100 shown in FIG. 10.
  • the flow shown in FIG. 12A is described by taking the video encoder 100 shown in FIG. 10 as an example where the execution body is executed.
  • the cross-component prediction method provided by the embodiment of the present application includes:
  • Step 110 Divide the image, and determine the intra prediction mode of the luminance component and the intra prediction mode of the chrominance component of the current coding block.
  • the color format of the video to which the image belongs includes but is not limited to 4:2:0, 4:2:2, etc.
  • the pixel ratio of the original pixel block of the luminance component of the current coding block to the original pixel block of the chrominance component is 4:1
  • the size of the original pixel block of the corresponding luminance component is 8*8
  • the size of the original pixel block of the corresponding chrominance component is 4*4.
  • the pixel ratio of the original pixel block of the luminance component and the original pixel block of the chrominance component of the current coding unit is 2:1
  • the size of the original pixel block of the corresponding luminance component is 8*8
  • the size of the original pixel block of the corresponding chrominance component is 8*4.
  • the intra-frame coded luminance component calculates up to 65 intra-frame prediction modes.
  • the luminance component performs calculations of up to 62 angle prediction modes and 3 non-angle prediction modes and selects an optimal one.
  • the intra-frame prediction mode is transmitted, and the intra-frame prediction mode of the chrominance component is calculated for up to 6 prediction modes.
  • the intra-frame prediction mode of the luminance component of the current coding block is the prediction mode with the best rate-distortion cost among the multiple intra-prediction modes, and the multiple intra-frame prediction modes are the intra-frame prediction modes of the luminance component of the current coding block.
  • Step 120 When the chrominance component intra prediction mode instructs to use the luminance component of the current coding block to derive the chrominance component of the current coding block, determine the current coding according to the luminance component intra prediction mode The reference prediction block for the chrominance component of the block.
  • the device may determine that the chrominance component intra prediction mode indicates that the chrominance component intra prediction mode is used to derive the luminance component of the current coding block when it is determined that the luminance component intra prediction mode is the preset intra prediction mode. Describe the chrominance component of the current coding block.
  • the preset intra prediction mode is a brightness component intra prediction mode in a preset direction, and the preset direction includes but is not limited to the horizontal direction (for example: along the X axis in the two-dimensional rectangular coordinate system XoY as shown in FIG.
  • vertical direction for example: along the negative direction of the Y axis in the two-dimensional rectangular coordinate system XoY as shown in Figure 1
  • diagonal direction for example: along the X in the two-dimensional rectangular coordinate system XoY as shown in Figure 1 Axis minus 45 degree angle direction).
  • Step 130 Filter the reference prediction block of the chrominance component of the current coding block to obtain the prediction block of the chrominance component of the current coding block.
  • the device can further calculate the reconstruction block of the color component, and determine the reconstruction block of the current coding block according to the reconstruction block of the chrominance component and the reconstruction block of the luminance component. Construct image blocks.
  • the solution of the present application uses the cross-component prediction mode to filter the reference prediction block of the chrominance component of the current coding block, which is beneficial to improve the compression efficiency of the coding block. Thereby improving coding efficiency.
  • the filtering the reference prediction block of the chrominance component of the current coding block includes: determining a filter according to the intra prediction mode of the luminance component; The reference prediction block of the chrominance component of the coding block is filtered.
  • the device determines a filter according to the intra prediction direction indicated by the luminance component intra prediction mode.
  • using the optimal intra prediction mode of the luminance component to guide the down-sampling operation of the chrominance component can increase the corresponding chrominance The vertical direction strength of the component, so as to achieve a better prediction effect.
  • using the optimal intra prediction mode of the luminance component to guide the down-sampling operation of the chrominance component can increase the corresponding chrominance The directional strength of the component in the horizontal direction, so as to achieve a better prediction effect.
  • using the optimal intra prediction mode of the luminance component to guide the down-sampling operation of the chrominance component can be increased Corresponding to the directional strength of the diagonal direction of the chrominance component, so as to achieve a better prediction effect.
  • the filter is determined by the luma component intra prediction mode, and the filter is used to filter the reference prediction block of the chroma component, so that the prediction of the chroma component can maintain the optimal mode of the corresponding luma component.
  • the main feature information that is, the main feature information of the image content maintains a high consistency in the luminance component and the chrominance component, which is beneficial to improve the compression efficiency of the coding block and achieve a better prediction effect.
  • the determining the filter according to the luminance component intra prediction mode includes: when the intra prediction direction indicated by the luminance component intra prediction mode is a horizontal direction, the filter setting It is the first filter.
  • the first filter includes a first two-tap filter for filtering the upper boundary pixel area of the reference prediction block of the chrominance component and a first two-tap filter for filtering the chrominance component.
  • the first three-tap filter for filtering with reference to the non-upper boundary pixel area of the prediction block.
  • the first two-tap filter includes:
  • the first three-tap filter includes:
  • the first three-tap filter includes:
  • x2 means multiplying by 2
  • x3 means multiplying by 3
  • the first row in the reference prediction block of the chrominance component Take the second row of pixels as an example.
  • d, pixel e, pixel f, pixel l, pixel m, and pixel n use the first three-tap filter to down-sample to form the pixel 3 of the prediction block of the chrominance component, and again, jump according to the step size 2, for the pixel f , Pixel g, pixel h, pixel n, pixel o, and pixel p are down-sampled using the first three-tap filter to form pixel 4 of the prediction block of the chrominance component, and so on for other columns.
  • the optimal intra prediction mode of the luminance component is used to guide the down-sampling operation of the chrominance component, and the corresponding color can be increased.
  • the directional strength of the degree component in the horizontal direction so as to achieve a better prediction effect.
  • the determining the filter according to the luminance component intra prediction mode includes: when the intra prediction direction indicated by the luminance component intra prediction mode is a horizontal direction, the filter setting It is the second filter.
  • the second filter includes a second two-tap filter for filtering the left boundary pixel area of the reference prediction block of the chrominance component and a second two-tap filter for filtering the chrominance component.
  • the second three-tap filter for filtering with reference to the non-left boundary pixel area of the prediction block.
  • the second two-tap filter includes:
  • the second three-tap filter includes:
  • x2 means multiplying by 2
  • x3 means multiplying by 3
  • the first column in the reference prediction block of the chrominance component Take the second column of pixels as an example.
  • Pixel c, pixel d, pixel e, pixel f, pixel g, and pixel h are down-sampled using the second three-tap filter to form pixel 2 of the prediction block of the chrominance component.
  • the selecting a filter for the current decoded block according to the luminance component intra prediction mode includes: when the intra prediction direction indicated by the luminance component intra prediction mode is diagonal In the direction, the filter is set as the third filter.
  • the third filter includes a third two-tap filter for filtering the left boundary pixel area and the upper boundary pixel area of the chrominance component reference prediction block and a third two-tap filter for filtering the
  • the chrominance component refers to the third three-tap filter for filtering pixel areas other than the left boundary pixel area and the upper boundary pixel area of the prediction block.
  • the third two-tap filter includes:
  • x and y are the coordinates of the current pixel
  • P′ C is the prediction sample of the luminance component of the current pixel
  • P C is the prediction sample of the chrominance component of the current pixel.
  • the third three-tap filter includes:
  • x and y are the coordinates of the current pixel
  • P′ C is the prediction sample of the luminance component of the current pixel
  • P C is the prediction sample of the chrominance component of the current pixel.
  • x2 means multiplying by 2
  • x3 means multiplying by 3
  • the diagonal direction in the reference prediction block of the chrominance component For example, for pixel a, pixel b, pixel c, and pixel d, use the third two-tap filter to down-sample to form pixel 1 of the prediction block of the brightness component.
  • the optimal intra prediction mode of the luminance component is used to guide the down-sampling operation of the chrominance component. Increase the directional intensity of the diagonal direction corresponding to the chrominance component, so as to achieve a better prediction effect.
  • the determining the reference prediction block of the chrominance component of the current coding block according to the luma component intra prediction mode includes: determining the current prediction block according to the luma component intra prediction mode A reconstruction block of the luminance component of the coding block; according to the reconstruction block of the luminance component of the current coding block, a reference prediction block of the chrominance component of the current coding block is determined.
  • the size of the reference prediction block of the chrominance component is the same as the size of the reconstructed block of the luminance component.
  • the reconstruction block of the luminance component and the reference prediction block of the chrominance component are both 8*8 pixel arrays.
  • the determining the reference prediction block of the chrominance component of the current coding block according to the reconstruction block of the luminance component of the current coding block includes: determining to use the luminance component of the current coding block A linear model of cross-component prediction is performed on the reconstruction block of the reconstruction block; the reconstruction block of the luminance component is calculated according to the linear model to obtain the reference prediction block of the chrominance component of the current coding block.
  • the linear model may be, for example, the linear model of the aforementioned formula (1).
  • the determining a linear model for cross-component prediction using a reconstructed block of the luminance component of the current coding block includes: determining a reference pixel used to calculate the linear model, and the reference pixel includes At least one neighboring pixel of the current coding block; calculating the linear model according to the reference pixel.
  • the device may select a linear model adapted to the current coding block from a plurality of linear models. Specifically, it may select a suitable linear model for the current coding block according to image characteristics. Because the coefficients of the linear model have not been determined yet, it needs to be calculated based on the reference pixels. It can be seen that, for the chrominance component prediction of the current coding block, the device can provide a more refined prediction mechanism relative to the coding unit, and achieve more refined image prediction.
  • the determining the reference pixels used to calculate the linear model includes: according to the available information of the reconstructed samples of the neighboring pixels of the current coding block and the chrominance component intra prediction mode To determine the reference pixel used to calculate the linear model.
  • the intra prediction mode of the chrominance component of the current coding block includes any one of TSCPM, TSCPM_T, and TSCPM_L.
  • the available information specifically includes available on both sides and available on one side (for example, available on the left side and available on the right side). The detailed description will be given below.
  • the intra prediction mode of the chrominance component of the current coding block is TSCPM
  • the available information is that the reconstructed samples of the upper neighboring pixels of the original pixel block corresponding to the current coding block are relative to the left side of the original pixel block of the current coding block.
  • Reconstructed samples of neighboring pixels are available, then the reference neighboring pixels used to calculate the coefficients of the linear model are 2 of the upper neighboring pixels and 2 of the left neighboring pixels of the original pixel block, as shown in Figure 6. (a) Shown.
  • the intra prediction mode of the chrominance component of the current coding block is TSCPM, and the available information is that the reconstructed samples of the upper neighboring pixels of the original pixel block corresponding to the current coding block are available, it is used as a reference for calculating the coefficients of the linear model
  • the adjacent pixels are 4 of the upper adjacent pixels of the original pixel block, as shown in FIG. 6(b).
  • the intra prediction mode of the chrominance component of the current coding block is TSCPM, and the available information is that the reconstructed samples of the left neighboring pixels of the original pixel block corresponding to the current coding block are available, it is used as a reference for calculating the coefficients of the linear model
  • the adjacent pixels are 4 of the adjacent pixels on the side of the original pixel block, as shown in Figure 6 (c).
  • the intra prediction mode of the chrominance component of the current coding block is TSCPM_T
  • the reconstructed sample of the upper neighboring pixel of the original pixel block corresponding to the current coding block and the left neighboring pixel of the original pixel block corresponding to the current coding block If the reconstructed sample of is available, the reference neighboring pixels used to calculate the coefficient of the linear model are 4 of the upper neighboring pixels of the original pixel block, as shown in Figure 6(b).
  • the intra prediction mode of the chrominance component of the current coding block is TSCPM_L
  • the reconstructed sample of the upper neighboring pixel of the original pixel block corresponding to the current coding block and the left neighboring pixel of the original pixel block corresponding to the current coding block If the reconstructed sample of is available, the reference neighboring pixels used to calculate the coefficient of the linear model are 4 of the side neighboring pixels of the original pixel block, as shown in Figure 6(c).
  • the reference neighboring pixels used to calculate the coefficients of the linear model can be flexibly set according to the availability of the reconstructed samples of the neighboring pixels and the intra prediction mode of the chrominance component.
  • the determining the reference pixels used to calculate the linear model includes: determining according to the luminance component intra prediction mode with the optimal rate-distortion cost of the adjacent coding blocks of the current coding block The reference pixel used to calculate the linear model.
  • the intra-frame prediction mode with the optimal rate-distortion cost of the luminance component of the adjacent coding block may be the same as or different from the intra-frame prediction mode with the optimal rate-distortion cost of the luminance component of the current coding unit.
  • FIG. 13 is a schematic flowchart of an image encoding method in an embodiment of this application.
  • the image encoding method can be applied to the target device in the video decoding system 1 shown in FIG. 9 20 or the video decoder 200 shown in FIG. 11.
  • the process shown in FIG. 13 is described by taking the video encoder 200 shown in FIG. 11 as an example in which the execution body is executed.
  • the cross-component prediction method provided by the embodiment of the present application includes:
  • Step 210 Parse the code stream to determine the intra prediction mode of the luminance component and the intra prediction mode of the chrominance component of the currently decoded block.
  • the color format of the video of the code stream includes but is not limited to 4:2:0, 4:2:2, etc.
  • the code stream can obtain a syntax element after entropy decoding, and the syntax element is used to determine the luma component intra prediction mode and the chroma component intra prediction mode for predicting the current decoded block.
  • the brightness component intra prediction mode is an optimal brightness component intra prediction mode among multiple intra prediction modes, and the multiple intra prediction modes are intra prediction modes used for intra prediction of the brightness component.
  • Step 220 When the chrominance component intra prediction mode indicates to use the reconstructed block of the luminance component of the currently decoded block to derive the prediction value of the chrominance component of the current decoded block, according to the luminance component intra prediction Mode, determining the reference prediction block of the chrominance component of the currently decoded block.
  • the device may determine that the chrominance component intra prediction mode indicates that the luminance component of the current decoded block is used to derive the data in the case of determining that the luminance component intra prediction mode is the preset intra prediction mode. Describe the chrominance component of the currently decoded block.
  • the preset intra prediction mode is a brightness component intra prediction mode in a preset direction, and the preset direction includes but is not limited to the horizontal direction (for example: along the X axis in the two-dimensional rectangular coordinate system XoY as shown in FIG.
  • vertical direction for example: along the negative direction of the Y axis in the two-dimensional rectangular coordinate system XoY as shown in Figure 1
  • diagonal direction for example: along the X in the two-dimensional rectangular coordinate system XoY as shown in Figure 1 Axis minus 45 degree angle direction).
  • Step 230 Filter the reference prediction block of the chrominance component of the currently decoded block to obtain the prediction block of the chrominance component of the currently decoded block.
  • the device can further calculate the reconstructed block of the color component, and determine the reconstruction block of the current decoded block according to the reconstructed block of the chrominance component and the reconstructed block of the luminance component. Construct an image.
  • the solution of the present application uses the cross-component prediction mode to filter the reference prediction block of the chrominance component of the current decoded block, which is beneficial to improve the compression of the decoded block. Efficiency, thereby improving decoding efficiency.
  • the filtering the reference prediction block of the chrominance component of the currently decoded block includes: determining a filter according to the luma component intra prediction mode; The reference prediction block of the chrominance component of the decoded block is filtered.
  • the device determines a filter according to the intra prediction direction indicated by the luminance component intra prediction mode.
  • the filter is determined by the intra prediction mode of the luminance component, and the filter is used to filter the reference decoding block of the chrominance component, so that the prediction of the chrominance component can maintain the optimal mode of the corresponding luminance component.
  • the main feature information that is, the main feature information of the image content maintains high consistency in the luminance component and the chrominance component, which is beneficial to improve the decoding efficiency of the decoded block and achieve a better prediction effect.
  • the determining the filter according to the luminance component intra prediction mode includes: when the intra prediction direction indicated by the luminance component intra prediction mode is a horizontal direction, the filter setting It is the first filter.
  • the first filter includes a first two-tap filter for filtering the upper boundary pixel area of the reference prediction block of the chrominance component and a first two-tap filter for filtering the chrominance component.
  • the first three-tap filter for filtering with reference to the non-upper boundary pixel area of the prediction block.
  • the first two-tap filter includes:
  • the first three-tap filter includes:
  • the first three-tap filter includes:
  • the optimal intra prediction mode of the luminance component is used to guide the down-sampling operation of the chrominance component, and the corresponding color can be increased.
  • the directional strength of the degree component in the horizontal direction so as to achieve a better prediction effect.
  • the determining the filter according to the luminance component intra prediction mode includes: when the intra prediction direction indicated by the luminance component intra prediction mode is a horizontal direction, the filter setting It is the second filter.
  • the second filter includes a second two-tap filter for filtering the left boundary pixel area of the reference prediction block of the chrominance component and a second two-tap filter for filtering the chrominance component.
  • the second three-tap filter for filtering with reference to the non-left boundary pixel area of the prediction block.
  • the second two-tap filter includes:
  • the second three-tap filter includes:
  • the selecting a filter for the current decoded block according to the luminance component intra prediction mode includes: when the intra prediction direction indicated by the luminance component intra prediction mode is diagonal In the direction, the filter is set as the third filter.
  • the third filter includes a third two-tap filter for filtering the left boundary pixel area and the upper boundary pixel area of the chrominance component reference prediction block and a third two-tap filter for filtering the
  • the chrominance component refers to the third three-tap filter for filtering pixel areas other than the left boundary pixel area and the upper boundary pixel area of the prediction block.
  • the third two-tap filter includes:
  • x and y are the coordinates of the current pixel
  • P′ C is the prediction sample of the luminance component of the current pixel
  • P C is the prediction sample of the chrominance component of the current pixel.
  • the third three-tap filter includes:
  • x and y are the coordinates of the current pixel
  • P′ C is the prediction sample of the luminance component of the current pixel
  • P C is the prediction sample of the chrominance component of the current pixel.
  • the optimal intra prediction mode of the luminance component is used to guide the down-sampling operation of the chrominance component. Increase the directional intensity of the diagonal direction corresponding to the chrominance component, so as to achieve a better prediction effect.
  • the determining the reference prediction block of the chrominance component of the currently decoded block according to the luma component intra prediction mode includes: determining the chrominance component intra prediction mode according to the chrominance component intra prediction mode.
  • the reconstruction block of the luminance component of the currently decoded block; and the reference prediction block of the chrominance component of the currently decoded block is determined according to the reconstructed block of the luminance component of the currently decoded block.
  • the size of the reference prediction block of the chrominance component is the same as the size of the reconstructed block of the luminance component.
  • the reconstruction block of the luminance component and the reference prediction block of the chrominance component are both 8*8 pixel arrays.
  • the determining the reference prediction block of the chrominance component of the current decoded block according to the reconstructed block of the luminance component of the current decoded block includes: determining to use the luminance component of the current decoded block A linear model for cross-component prediction is performed on the reconstruction block of the reconstruction block; the reconstruction block of the luminance component is calculated according to the linear model to obtain the reference prediction block of the chrominance component of the currently decoded block.
  • the linear model may be, for example, the linear model of the aforementioned formula (1).
  • the determining a linear model for cross-component prediction using a reconstructed block of the luminance component of the current decoded block includes: determining a reference pixel used to calculate the linear model, and the reference pixel includes At least one adjacent pixel of the current decoding block; calculating the linear model according to the reference pixel.
  • the device may select a linear model adapted to the current decoding block from multiple linear models. Specifically, it may select a suitable linear model for the current decoding block according to image characteristics. Because the coefficients of the linear model have not been determined yet, it needs to be calculated based on the reference pixels. It can be seen that the device predicts the chrominance component of the current decoded block, and can provide a more refined prediction mechanism relative to the coding unit to achieve more refined image prediction.
  • the determining the reference pixels used to calculate the linear model includes: according to the available information of the reconstructed samples of the neighboring pixels of the current decoding block and the chrominance component intra prediction mode To determine the reference pixel used to calculate the linear model.
  • the intra prediction mode of the chrominance component of the currently decoded block includes any one of TSCPM, TSCPM_T, and TSCPM_L.
  • the available information specifically includes available on both sides and available on one side (for example, available on the left side and available on the right side).
  • the intra prediction mode of the chrominance component of the currently decoded block includes any one of TSCPM, TSCPM_T, and TSCPM_L.
  • the available information specifically includes available on both sides and available on one side (for example, available on the left side and available on the right side). The detailed description is given below.
  • the intra prediction mode of the chrominance component of the current decoded block is TSCPM
  • the available information is the reconstructed sample of the upper adjacent pixel of the original pixel block corresponding to the current decoded block and the left side of the original pixel block of the current decoded block.
  • the reconstructed samples of the neighboring pixels are available, and the reference neighboring pixels used to calculate the coefficients of the linear model are 2 of the upper neighboring pixels and 2 of the left neighboring pixels of the original pixel block, as shown in Figure 6. (a) Shown.
  • the intra prediction mode of the chrominance component of the current decoded block is TSCPM, and the available information is that the reconstructed samples of the upper neighboring pixels of the original pixel block corresponding to the current decoded block are available, it is used as a reference for calculating the coefficients of the linear model
  • the adjacent pixels are 4 of the upper adjacent pixels of the original pixel block, as shown in FIG. 6(b).
  • the intra prediction mode of the chrominance component of the current decoded block is TSCPM, and the available information is that the reconstructed samples of the left neighboring pixels of the original pixel block corresponding to the current decoded block are available, it is used as a reference for calculating the coefficients of the linear model
  • the adjacent pixels are 4 of the adjacent pixels on the side of the original pixel block, as shown in Figure 6 (c).
  • the intra prediction mode of the chrominance component of the current decoded block is TSCPM_T
  • the reconstructed sample of the upper neighboring pixel of the original pixel block corresponding to the current decoded block and the left neighboring pixel of the original pixel block corresponding to the current decoded block If the reconstructed sample of is available, the reference neighboring pixels used to calculate the coefficient of the linear model are 4 of the upper neighboring pixels of the original pixel block, as shown in Figure 6(b).
  • the intra prediction mode of the chrominance component of the current decoded block is TSCPM_L
  • the reconstructed sample of the upper neighboring pixel of the original pixel block corresponding to the current decoded block and the left neighboring pixel of the original pixel block corresponding to the current decoded block If the reconstructed sample of is available, the reference neighboring pixels used to calculate the coefficient of the linear model are 4 of the side neighboring pixels of the original pixel block, as shown in Figure 6(c).
  • the reference neighboring pixels used to calculate the coefficients of the linear model can be flexibly set according to the availability of the reconstructed samples of the neighboring pixels and the intra prediction mode of the chrominance component.
  • the determining the reference pixel used to calculate the linear model includes: determining the luminance component intra prediction mode with the optimal rate-distortion cost of the adjacent decoding block of the current decoding block The reference pixel used to calculate the linear model.
  • the intra-frame prediction mode of the luminance component of the adjacent decoded block may be the same as or different from the intra-frame prediction mode of the luminance component of the current decoding unit.
  • Digital video coding and decoding technology mainly uses coding bitrate and peak signal-to-noise ratio (PSNR) for comparison in measuring performance indicators.
  • PSNR peak signal-to-noise ratio
  • the test experiment of this application scheme is in the reference software High-Performance Model (HPM) of AVS3, general test conditions Performed under the common test condition (CTC).
  • HPM High-Performance Model
  • CTC common test condition
  • An embodiment of the present application provides an image encoding device, and the image encoding device may be a video decoder or a video encoder. Specifically, the image encoding device is used to perform the steps performed by the video decoder in the above decoding method.
  • the image encoding device provided in the embodiment of the present application may include modules corresponding to corresponding steps.
  • the embodiment of the present application may divide the image encoding device into functional modules according to the foregoing method examples.
  • each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module.
  • the above-mentioned integrated modules can be implemented in the form of hardware or software functional modules.
  • the division of modules in the embodiments of the present application is illustrative, and is only a logical function division, and there may be other division methods in actual implementation.
  • FIG. 14 shows a possible schematic structural diagram of the image encoding device involved in the foregoing embodiment.
  • the image encoding device 14 includes a dividing unit 140, a determining unit 141, and a filtering unit 142.
  • the dividing unit 140 is configured to divide an image and determine the intra prediction mode of the luminance component and the intra prediction mode of the chrominance component of the current coding block;
  • the determining unit 141 is configured to, when the chrominance component intra prediction mode instructs to use the luminance component of the current coding block to derive the chrominance component of the current coding block, determine the chrominance component according to the luminance component intra prediction mode The reference prediction block of the chrominance component of the current coding block;
  • the filtering unit 142 is configured to filter the reference prediction block of the chrominance component of the current coding block to obtain the prediction block of the chrominance component of the current coding block.
  • the image encoding device provided by the embodiment of the present application includes but is not limited to the above-mentioned modules.
  • the image encoding device may further include a storage unit 143.
  • the storage unit 143 may be used to store the program code and data of the image encoding device.
  • the image encoding device 15 includes: a processing module 150 and a communication module 151.
  • the processing module 150 is used to control and manage the actions of the image encoding device, for example, to perform the steps performed by the dividing unit 140, the determining unit 141, and the filtering unit 142, and/or to perform other processes of the technology described herein.
  • the communication module 151 is used to support the interaction between the image encoding device and other devices.
  • the image encoding device may further include a storage module 152, which is used to store the program code and data of the image encoding device, for example, to store the content saved by the storage unit 143 described above.
  • the processing module 150 may be a processor or a controller, for example, a central processing unit (Central Processing Unit, CPU), a general-purpose processor, a digital signal processor (Digital Signal Processor, DSP), ASIC, FPGA or other programmable Logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logical blocks, modules, and circuits described in conjunction with the disclosure of this application.
  • the processor may also be a combination for realizing computing functions, for example, including a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and so on.
  • the communication module 151 may be a transceiver, an RF circuit, a communication interface, or the like.
  • the storage module 152 may be a memory.
  • the image encoding device 14 and the image encoding device 15 described above can both execute the image encoding method shown in FIG. 12A.
  • the image encoding device 14 and the image encoding device 15 may specifically be video image encoding devices or other devices with video encoding functions.
  • the present application also provides a video encoder, including a non-volatile storage medium, and a central processing unit, the non-volatile storage medium stores an executable program, the central processing unit and the non-volatile storage The media is connected, and the executable program is executed to implement the image encoding method of the embodiment of the present application.
  • An embodiment of the present application provides an image decoding device, and the image decoding device may be a video decoder or a video decoder. Specifically, the image decoding device is used to execute the steps performed by the video decoder in the above decoding method.
  • the image decoding device provided in the embodiment of the present application may include modules corresponding to corresponding steps.
  • the embodiment of the present application may divide the image decoding apparatus into functional modules according to the foregoing method examples.
  • each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module.
  • the above-mentioned integrated modules can be implemented in the form of hardware or software functional modules.
  • the division of modules in the embodiments of the present application is illustrative, and is only a logical function division, and there may be other division methods in actual implementation.
  • FIG. 16 shows a possible schematic diagram of the structure of the image decoding device involved in the foregoing embodiment.
  • the image decoding device 16 includes an analysis unit 160, a determination unit 161, and a filtering unit 162.
  • the parsing unit 160 is configured to analyze the code stream and determine the intra prediction mode of the luminance component and the intra prediction mode of the chrominance component of the current decoded block;
  • the determining unit 161 is configured to: when the chrominance component intra prediction mode instructs to use the reconstructed block of the luminance component of the current decoded block to derive the prediction value of the chrominance component of the current decoded block, according to the luminance component Intra-frame prediction mode, determining the reference prediction block of the chrominance component of the currently decoded block;
  • the filtering unit 162 is configured to filter the reference prediction block of the chrominance component of the currently decoded block to obtain the prediction block of the chrominance component of the currently decoded block.
  • the image decoding device provided by the embodiment of the present application includes but is not limited to the above-mentioned modules.
  • the image decoding device may further include a storage unit 163.
  • the storage unit 163 may be used to store the program code and data of the image decoding device.
  • the image decoding device 17 includes: a processing module 170 and a communication module 171.
  • the processing module 170 is used to control and manage the actions of the image decoding device, for example, to execute the steps performed by the parsing unit 160, the determining unit 161, and the filtering unit 162, and/or to perform other processes of the technology described herein.
  • the communication module 171 is used to support the interaction between the image decoding device and other devices.
  • the image decoding device may further include a storage module 172, which is used to store the program code and data of the image decoding device, for example, to store the content saved by the storage unit 163 described above.
  • the processing module 170 may be a processor or a controller, for example, a central processing unit (CPU), a general-purpose processor, a digital signal processor (Digital Signal Processor, DSP), an ASIC, an FPGA, or other programmable processors. Logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logical blocks, modules, and circuits described in conjunction with the disclosure of this application.
  • the processor may also be a combination of computing functions, for example, a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and so on.
  • the communication module 171 may be a transceiver, an RF circuit, a communication interface, or the like.
  • the storage module 172 may be a memory.
  • Both the image decoding device 16 and the image decoding device 17 can execute the image decoding method shown in FIG. 13.
  • the image decoding device 16 and the image decoding device 17 may specifically be video image decoding devices or other devices with video decoding functions.
  • the present application also provides a video decoder, including a non-volatile storage medium, and a central processing unit, the non-volatile storage medium stores an executable program, the central processing unit and the non-volatile storage The media is connected, and the executable program is executed to implement the image decoding method of the embodiment of the present application.
  • the present application also provides a terminal, which includes: one or more processors, memories, and communication interfaces.
  • the memory and the communication interface are coupled with one or more processors; the memory is used to store computer program codes, and the computer program codes include instructions.
  • the terminal executes the image encoding and/ Or image decoding method.
  • the terminals here can be video display devices, smart phones, portable computers, and other devices that can process or play videos.
  • Another embodiment of the present application further provides a computer-readable storage medium.
  • the computer-readable storage medium includes one or more program codes, and the one or more programs include instructions.
  • the processor in the decoding device is executing the program
  • the decoding device executes the image encoding method and image decoding method in the embodiments of the present application.
  • a computer program product in another embodiment of the present application, includes computer-executable instructions stored in a computer-readable storage medium; at least one processor of the decoding device can be downloaded from the computer
  • the readable storage medium reads the computer-executed instruction, and at least one processor executes the computer-executed instruction to enable the terminal to implement the image encoding method and image decoding method of the embodiments of the present application.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • 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.
  • the computer instructions may be transmitted from a website, 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 (DSL)) or wireless (such as infrared, wireless, microwave, etc.).
  • the computer-readable storage medium such as coaxial cable, optical fiber, digital subscriber line (DSL)
  • wireless such as infrared, wireless, microwave, etc.
  • the quality can be any available medium that can be accessed by a computer or a data storage device such as a server or data center integrated with one or more available media.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)).
  • the disclosed device and method may be implemented in other ways.
  • the device embodiments described above are merely illustrative.
  • the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods, for example, multiple units or components may be divided. It can be combined or integrated into another device, or some features can be omitted or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate parts may or may not be physically separate.
  • the parts displayed as units may be one physical unit or multiple physical units, that is, they may be located in one place, or they may be distributed to multiple different places. . Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
  • the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.
  • the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium.
  • the technical solutions of the embodiments of the present application are essentially or the part that contributes to the prior art, or all or part of the technical solutions can be embodied in the form of a software product, and the software product is stored in a storage medium. It includes several instructions to make a device (which may be a single-chip microcomputer, a chip, etc.) or a processor (processor) execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage media include: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program code .

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Abstract

本申请实施例公开了一种图像编码方法、图像解码方法及相关装置，图像解码方法包括：划分图像，确定当前编码块的亮度分量帧内预测模式和色度分量帧内预测模式；当所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量时，根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块；对所述当前编码块的色度分量的参考预测块进行滤波，得到所述当前编码块的色度分量的预测块。本申请实施例在跨分量预测模式中实现对当前像素块的色度分量的参考预测块进行滤波，有利于提高像素块的压缩效率。

Description

图像编码方法、图像解码方法及相关装置 技术领域
本申请涉及电子设备技术领域，具体涉及一种图像编码方法、图像解码方法及相关装置。
背景技术
数字视频能力可并入到大范围的装置中，包含数字电视、数字直播系统、无线广播系统、个人数字助理(personal digital assistant，PDA)、膝上型或桌上型计算机、平板计算机、电子书阅读器、数码相机、数字记录装置、数字媒体播放器、视频游戏装置、视频游戏控制台、蜂窝式或卫星无线电电话、视频会议装置、视频流装置等等。
数字视频装置实施视频压缩技术，例如由MPEG-2、MPEG-4、ITU-TH.263、ITU-TH.264/MPEG-4第10部分高级视频编解码(advanced video coding，AVC)、ITU-TH.265高效率视频编解码(high efficiency video coding，HEVC)标准定义的标准和所述标准的扩展部分中所描述的那些视频压缩技术，从而更高效地发射及接收数字视频信息。视频装置可通过实施这些视频编解码技术来更高效地发射、接收、编码、解码和/或存储数字视频信息。
随着互联网视频的激增，尽管数字视频压缩技术不断演进，但仍然对视频压缩比提出更高要求。
发明内容
本申请实施例提供了一种图像编码方法、图像解码方法及相关装置，以期在跨分量预测模式中，根据当前编码单元的不同方向性使用不同滤波器进行降采样。
第一方面，本申请实施例提供一种图像编码方法，包括：划分图像，确定当前编码块的亮度分量帧内预测模式和色度分量帧内预测模式；当所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量时，根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块；对所述当前编码块的色度分量的参考预测块进行滤波，得到所述当前编码块的色度分量的预测块。
相比于现有技术，本申请方案利用在跨分量预测模式中实现对当前编码块的色度分量的参考预测块进行滤波，有利于提高编码块的压缩效率，从而提高编码效率。
第二方面，本申请实施例提供一种图像解码方法，包括：解析码流，确定当前解码块的亮度分量帧内预测模式和色度分量帧内预测模式；当所述色度分量帧内预测模式指示使用所述当前解码块的亮度分量的重构块推导所述当前解码块的色度分量的预测值时，根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块；对所述当前解码块的色度分量的参考预测块进行滤波，得到所述当前解码块的色度分量的预测块。
相比于现有技术，本申请方案利用在跨分量预测模式中实现对当前解码块的色度分量的参考预测块进行滤波，有利于提高解码块的压缩效率，从而提高解码效率。
第三方面，本申请实施例提供一种图像编码装置，包括：划分单元，用于划分图像，确定当前编码块的亮度分量帧内预测模式和色度分量帧内预测模式；确定单元，用于当所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量时，根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块；滤波单元，用于对所述当前编码块的色度分量的参考预测块进行滤波，得到所述当前编码块的色度分量的预测块。
第四方面，本申请实施例提供一种图像解码装置，包括：解析单元，用于解析码流，确定当前解码块的亮度分量帧内预测模式和色度分量帧内预测模式；确定单元，用于当所述色度分量帧内预测模式指示使用所述当前解码块的亮度分量的重构块推导所述当前解码块的色度分量的预测值时，根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块；滤波单元，用于对所述当前解码块的色度分量的参考预测块进行滤波，得到所述当前解码块的色度分量的预测块。
第五方面，本申请实施例提供了一种编码器，包括：处理器和耦合于所述处理器的存储器；所述处理器用于执行上述第一方面所述的方法。
第六方面，本申请实施例提供了一种解码器，包括：处理器和耦合于所述处理器的存储器；所述处理器用于执行上述第二方面所述的方法。
第七方面，本申请实施例提供了一种终端，所述终端包括：一个或多个处理器、存储器和通信接口；所述存储器、所述通信接口与所述一个或多个处理器连接；所述终端通过所述通信接口与其他设备通信，所述存储器用于存储计算机程序代码，所述计算机程序代码包括指令，当所述一个或多个处理器执行所述指令时，所述终端执行如第一方面或第二方面所述的方法。
第八方面，本申请实施例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中存储有指 令，当所述指令在计算机上运行时，使得计算机执行上述第一方面或第二方面所述的方法。
第九方面，本申请实施例提供了一种包含指令的计算机程序产品，当所述指令在计算机上运行时，使得计算机执行上述第一方面或第二方面所述的方法。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例中编码树单元的一种示意性框图；
图2为本申请实施例中颜色格式的一种示意性框图；
图3为本申请实施例中CTU和编码单元CU的一种示意性框图；
图4为本申请实施例中的编码单元的关联像素一种示意性框图；
图5为本申请实施例中亮度分量帧内预测模式的一种示意性框图；
图6为本申请实施例中用于线性模型的系数的计算的相邻像素的一种示意性框图；
图7为本申请实施例中降采样滤波器的一种示意性框图；
图8为本申请实施例中从亮度分量重构块到色度分量预测块变化的一种示意性框图；
图9为本申请实施例中视频译码系统的一种示意性框图；
图10为本申请实施例中视频编码器的一种示意性框图；
图11为本申请实施例中视频解码器的一种示意性框图；
图12A为本申请实施例中一种图像编码方法的流程示意图；
图12B为本申请实施例中一种水平方向的降采样过程的示意图；
图12C为本申请实施例中一种垂直方向的降采样过程的示意图；
图12D为本申请实施例中一种对角线方向的降采样过程的示意图；
图13为本申请实施例中一种图像解码方法的流程示意图；
图14为本申请实施例中图像编码装置的一种功能单元框图；
图15为本申请实施例中图像编码装置的另一种功能单元框图；
图16为本申请实施例中图像解码装置的一种功能单元框图；
图17为本申请实施例中图像解码装置的另一种功能单元框图。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
可以理解，本发明所使用的术语“第一”、“第二”等可在本文中用于描述各种元件，但这些元件不受这些术语限制。这些术语仅用于将第一个元件与另一个元件区分。举例来说，在不脱离本发明的范围的情况下，可以将第一客户端称为第二客户端，且类似地，可将第二客户端称为第一客户端。第一客户端和第二客户端两者都是客户端，但其不是同一客户端。
首先介绍一下本申请实施例中用到的
术语和相关技术。
对于图像的划分，为了更加灵活的表示视频内容，高效率视频编解码(High Efficiency Video Coding standard，HEVC)技术中定义了编码树单元(coding tree unit，CTU)、编码单元(Coding Unit，CU)、预测单元(Prediction Unit，PU)和变换单元(Transform Unit，TU)。CTU、CU、PU和TU均为图像块。
编码树单元CTU，一幅图像由多个CTU构成，一个CTU通常对应于一个方形图像区域，包含这个图像区域中的亮度像素和色度像素(或者也可以只包含亮度像素，或者也可以只包含色度像素)；CTU中还包含语法元素，这些语法元素指示如何将CTU划分成至少一个编码单元(coding unit，CU)，以及解码每个编码单元得到重建图像的方法。如图1中的(a)所示，图像10由多个CTU构成(包括CTU A、CTU B、CTU C等)。与某一CTU对应的编码信息包含与该CTU对应的方形图像区域中的像素的亮度值和/或色度值。此外，与某一CTU对应的编码信息还可以包含语法元素，这些语法元素指示如何将该CTU划分成至少一个CU，以及解码每个CU以得到重建图像的方法。一个CTU对应的图像区域可以包括64×64、128×128或256×256个像素。在一个示例中，64×64个像素的CTU包含由64列、每列64个像素的矩形像素点阵，每个像素包含亮度分量和/或色度分量。CTU也可以对应矩形图像区域或者其它形状的图像区域，一个CTU对应的图像区域也可以是水平方向的像素点的数量与竖直方向的像素点数量不同的图像区域，例如包括64×128个像素。
编码单元CU，通常对应于图像中一个A×B的矩形区域，包含A×B亮度像素或/和它对应的色度像素，A为矩形的宽，B为矩形的高，A和B可以相同也可以不同，A和B的取值通常为2的整数次幂，例如128、64、32、16、8、4。其中，本申请实施例中涉及到的宽是指图1示出的二维直角坐标系XoY中沿X轴方向(水平方向)的长度，高是指图1示出的二维直角坐标系XoY中沿Y轴方向(竖直方向)的长度。一个CU的重建图像可以通过预测图像与残差图像相加得到，预测图像通过帧内预测或帧间预测生成，具体可以由一个或多个预测块(prediction block，PB)构成，残差图像通过对变换系数进行反量化和反变换处理生成，具体可以由一个或多个变换块(transform block，TB)构成。具体的，一个CU包含编码信息，编码信息包括预测模式、变换系数等信息，按照这些编码信息对CU进行相应的预测、反量化、反变换等解码处理，产生这个CU对应的重建图像。
预测单元PU，是帧内预测、帧间预测的基本单元。定义图像块的运动信息包含帧间预测方向、参考帧、运动矢量等，正在进行编码处理的图像块称为当前编码块(current coding block，CCB)，正在进行解码处理的图像块称为当前解码块(current decoding block，CDB)，例如正在对一个图像块进行预测处理时，当前编码块或者当前解码块为预测块；正在对一个图像块进行残差处理时，当前编码块或者当前解码块为变换块。当前编码块或当前解码块所在的图像称为当前帧。当前帧中，位于当前块的左侧或上侧的图像块可能处于当前帧内部并且已经完成了编码/解码处理，得到了重建图像，它们称为重建块；重建块的编码模式、重建像素等信息是可以获得的(available)。在当前帧进行编码/解码之前已经完成编码/解码处理的帧称为重建帧。当前帧为单向预测帧(P帧)或双向预测帧(B帧)时，它分别具有一个或两个参考帧列表，两个列表分别称为L0和L1，每个列表中包含至少一个重建帧，称为当前帧的参考帧。参考帧为当前帧的帧间预测提供参考像素。
变换单元TU，对原始图像块和预测图像块的残差进行处理。
像素(又称为像素点)，是指图像中的像素点，如编码单元中的像素点、亮度分量像素块中的像素点(又称为亮度像素)、色度分量像素块中的像素点(又称为色度像素)等。
样本(又称为像素值)，是指像素点的像素值，该像素值在亮度分量域具体是指亮度(即灰阶值)，该像素值在在色度分量域具体是指色度值(即色彩和饱和度)，按照处理阶段的不同，一个像素的样本具体包括原始样本、预测样本和重构样本。
帧内预测，根据当前块的空间相邻像素，产生当前块的预测图像。一种帧内预测模式对应于一种生成预测图像的方法。帧内预测单元的划分包括2N×2N划分方式(如图2中的A所示)和N×N划分方式(如图2中的B所示)，2N×2N划分方式为对图像块不进行划分；N×N划分方式为将图像块划分为四个等大的子图像块。
通常，数字视频压缩技术作用于颜色编码方法为YCbCr，也可称为YUV，颜色格式为4:2:0、4:2:2或4:4:4的视频序列。其中，Y表示明亮度(Luminance或Luma)，也就是灰阶值，Cb表示蓝色色度分量，Cr表示红色色度分量，U和V表示色度(Chrominance或Chroma)，用于描述色彩及饱和度。在颜色格式上，4:2:0表示每4个像素有4个亮度分量，2个色度分量(YYYYCbCr)，4:2:2表示每4个像素有4个亮度分量，4个色度分量(YYYYCbCrCbCr)，而4:4:4表示全像素显示(YYYYCbCrCbCrCbCrCbCr)，图2展示了不同颜色格式下的各分量分布图，其中圆形为Y分量，三角形为UV分量。
在数字视频编码过程中，编码器对不同颜色格式的原始视频序列读取像素并编码。一般数字编码器中通常包含，预测、变换与量化、反变换与反量化、环路滤波以及熵编码等，用于消除空间、时间、视觉以及字符冗余等。然而人眼对亮度分量的变化更为敏感，而对色度分量变化并没有强烈的反应，因此在原始视频序列中一般采用YUV 4:2:0的颜色格式进行编码。同时，数字视频编码器在帧内编码部分对亮度分量和色度分量采取不同的预测过程，亮度分量的预测更为细致和复杂，而色度分量的预测则通常比较简单。跨分量预测(Cross Component Prediction,CCP)模式是现有数字视频编里的一种作用于亮度分量和色度分量以提高视频压缩比的技术。
跨分量预测模式具体实施过程作用于帧内编码中，该方法包括使用亮度块(Luminance Block)的训练样本来确定用于预测色度块(Chrominance Block)的线性模型(Linear Model)，以及使用亮度块的样本和线性模型来确定色度块的样本。其中，亮度块和色度块为编码单元在亮度分量和色度分量中的像素块，数字视频编码器通常会将原始视频序列读取成一帧一帧的图像并将图像分割成编码树单元CTU，而编码树单元又可继续划分为不同与相同大小的编码单元CU，具体编码过程在不同分量的编码单元中进行，编码树单元与编码单元关系如图3所示。
跨分量预测(CCP)的实例：在最新视频编解码(Versatile Video Coding,VVC)标准中，使用跨分量线性模型(Cross Component Linear Model,CCLM)来减少分量之间的冗余。其线性模型通过当前编码单元的亮度分量的原始像素块的相邻像素的原始样本与重构样本训练得到，该相邻像素的样本信息包 括当前编码单元的亮度分量的原始像素块的上侧相邻像素的原始样本与重构样本，当前编码单元的亮度分量的原始像素块的右上侧毗邻像素的原始样本与重构样本，当前编码单元的亮度分量的原始像素块的左侧相邻像素的原始样本与重构样本，当前编码单元亮度分量的原始像素块的左下侧毗邻像素的原始样本与重构样本。图4分别展示了颜色格式YUV4:2:0之下的一个8x8的亮度分量的原始像素块与相邻像素、以及4x4的色度分量的原始预测像素块与相邻像素的位置关系示例。
在当前编码单元中，色度分量预测块中像素的预测样本由当前编码单元的亮度分量的原始像素块中的像素的重构样本经过线性模型计算并降采样得到，其中，线性模型计算过程表示如下：
Pred C(i,j)＝α·Rec L(i,j)+β  (1)
其中，(i，j)为像素的坐标，x具体是指当前编码单元的色度分量的预测块的横坐标，其范围为[0,width-1],步长为1，width为当前编码单元的色度分量的预测块的宽度，其取值可为4，8，16及32；y具体是指当前编码单元的色度分量的预测块的纵坐标，其范围为[0,height-1]，步长为1，height为当前编码单元的色度分量的预测块的高度，其取值可为4，8，16及32，Rec L为亮度分量的原始像素块中的像素的重构样本，Rec L为色度分量的预测块中像素的预测样本，α、β为线性模型的系数。
在另一跨分量预测实例中，中国数字音视频编解码标准(Audio Video coding Standard,AVS)最新采纳的跨分量技术提案M4612，两步跨分量预测模式(Two Step Cross-component Prediction Mode,TSCPM)。在编码过程中，如图5所示，帧内编码亮度分量计算最多65个帧内预测模式(Intra Prediction mode)，DC表示均值模式，Plane表示平面模式，Bilinear表示双线性模式，Zone表示区域。根据码率失真(Rate Distortion)代价选出最优结果并传输该帧内预测模式和相应预测残差等。在对色度分量的预测块的像素进行跨分量技术预测时，当前编码单元的亮度分量的原始像素块的相邻像素的重构样本以及当前编码单元的色度分量的原始预测像素块的相邻像素的重构样本被用于线性模型的计算。上述亮度分量的原始像素块的相邻像素包括，当前编码单元的亮度分量的原始像素块的上侧相邻像素以及左侧相邻像素；上述色度分量的预测块的相邻像素包括，当前编码单元色度分量的预测块的上侧相邻像素以及左侧相邻像素。
在选取重构样本作为计算线性模型的系数的参考样本时，结合相邻像素的重构样本的可用性，可以采用上侧相邻像素中两个像素的重构样本与左侧相邻像素中两个像素的重构样本的组合，还可以全部采用上侧相邻像素中四个像素的重构样本，以及全部采用左侧相邻像素中四个像素的重构样本。
根据上述参考样本的选择不同，预测模式包括，若当前编码单元对应的亮度分量的原始像素块和色度分量的原始像素块(为描述方便本端统称为原始像素块)的上侧相邻像素的重构样本和当前编码单元的原始像素块的左侧相邻像素的重构样本可用，且线性模型的系数计算采用的参考样本同时来自上侧和左侧的相邻像素时，或若当前编码单元对应的原始像素块只有上侧相邻像素的重构样本可用，且线性模型系数计算采用的参考样本只选上侧相邻像素的重构样本时，或若当前编码单元对应的原始像素块只有左侧相邻像素的重构样本可用，且线性模型的系数的计算采用的参考样本只选左侧相邻像素的重构样本时，均为TSCPM模式；若当前编码单元对应的原始像素块的上侧相邻像素的重构样本和当前编码单元对应的原始像素块的左侧相邻像素的重构样本可用，且线性模型计算的系数的计算采用的参考样本只选上侧相邻像素的重构样本时，为TSCPM_T模式；若当前编码单元对应的原始像素块的上侧相邻像素的重构样本和当前编码单元对应的原始像素块的左侧相邻像素的重构样本可用，且线性模型的系数的计算采用的参考样本只选上侧相邻像素的重构样本时，为TSCPM_L模式。
上述用于线性模型的系数的计算的参考样本中，如图6所示，若参考样本来自当前编码单元对应的原始像素块的两侧的相邻像素时，则上侧的参考样本选取上侧相邻像素中最左端像素的重构样本与当前编码单元块对应的原始像素块的宽度的上侧最右端像素的重构样本，左侧参考样本选取左侧相邻像素中最上端像素的重构样本与当前编码单元对应的原始像素块的高度的左侧相邻像素中最下端像素的重构样本；若用于线性模型的系数的计算的参考样本只来自上侧时，则以当前编码单元对应的原始像素块的宽度的四分之一距离为步长，选取上侧相邻像素中四个连续步长的像素的重构样本；若参考样本只来自左侧时，则以当前编码单元对应的原始像素块的高度的四分之一距离为步长，选取四个左侧相邻像素中四个连续步长的像素的重构样本。
上述具体实例AVS3中，跨分量技术的线性模型计算式与上述式(1)相同，其中α和β可通过以下式子计算得到：
α＝(Y Max-Y Min)/(X Max-X Min)  (2)
β＝Y Min-α·X Min  (3)
其中，Y Max为用于线性模型的系数的计算的色度分量的原始像素块的多个相邻像素点的重构样本中两个最大重构样本的平均值，Y Min为用于线性模型的系数的计算的色度分量的原始像素块的多个相邻像素点的重构样本中两个最小重构样本的平均值。X Max为用于线性模型的系数的计算的亮度分量的原始像素块的多个相邻像素点的重构样本中的两个最大重构样本的平均值，X Min为用于线性模型的系数的计算的亮度分量的原始像素块的多个相邻像素点的重构样本中的两个最小重构样本的平均值。
根据计算得到的线性模型进行跨分量预测，当前CU的亮度分量重构块被用于生成相对应的色度分量参考预测块(Chroma Reference Prediction Pixel Block)。具体根据式(1)、(2)和(3)计算出当前编码单元的每个像素的色度分量的参考预测样本，该色度分量参考预测块的尺寸与亮度分量的原始像素块的尺寸相同。在具体实例中，输入数字视频颜色格式一般为YUV4:2:0格式，即色度分量预测块的大小为亮度分量的原始像素块的四分之一。为得到相对应的正确大小色度分量预测块，该色度分量参考预测块需要分别对水平和垂直方向进行二分之一降采样，经过降采样之后的色度分量预测块为相对应的亮度分量的原始像素块四分之一，满足颜色格式约束的尺寸要求。其中，上述对色度分量参考预测块进行降采样所采用的滤波器在该色度分量参考预测块的左边界像素区域采用两抽头相同系数的降采样滤波器，而在其他像素区域均采用六抽头两不同系数的降采样滤波器。
六抽头两不同系数的降采样滤波器如式(4)所示。
Figure PCTCN2021081132-appb-000001
或者如(4-1)所示：
Figure PCTCN2021081132-appb-000002
其中，x，y为像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000003
和
Figure PCTCN2021081132-appb-000004
为所述当前像素的色度分量的预测样本。
两抽头相同系数的降采样滤波器如式(5)所示。
Figure PCTCN2021081132-appb-000005
其中，x，y为像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000006
和
Figure PCTCN2021081132-appb-000007
为所述当前像素的色度分量的预测样本。
该降采样滤波器如图7所示，其中，x1表示乘以1，x2表示乘以2。图8展示了跨分量技术从亮度分量重构块到色度分量预测块变化的示意图，其中，编码单元的亮度分量重构块尺寸为8*8，对应的色度分量参考预测块的尺寸为8*8，滤波后的色度分量预测块的尺寸为4*4。
通常而言，自然视频中包含各种角度方向的特征信息，在图像的帧内编码过程中，图像的亮度分量的原始像素块可以根据多个角度的帧内预测模式进行计算，并选出最优的帧内预测模式以得到更好的角度预测效果和提高压缩效率。现有图像编解码技术利用当前编码单元预测完成的亮度分量重构块，进行线性变换得到当前编码单元的色度分量参考预测块，该色度分量参考预测块包含较多亮度分量的特征信息，如方向特征等。使用单一固定的滤波器的降采样方式对该暂时色度分量预测块进行降采样，并没有考虑到当前视频内容的一些突出特征信息，将所有内容进行统一模糊，此种使用单一固定的滤波器的降采样方式降低了色度分量的各种方向信息强度，降低了视频压缩的效率。
针对上述技术问题，本申请提出如下设计思路，在数字视频编解码中，亮度分量与色度分量的帧内预测过程有较大不同，亮度分量进行最多62个角度预测模式和3个非角度预测模式的计算并选出一个最优帧内预测模式进行传输，而色度分量的帧内预测模式最多进行6个预测模式的计算，亮度分量的帧内预测过程更为精确。在同一个编码单元中，亮度分量与色度分量具有特征一致性，即图像内容的主要特征信息在不同分量中保持一致，且不因线性变换而改变。因此，在亮度分量经过65个帧内预测模式计算选出的最优模式下，亮度分量的重构块进行线性变换后的色度分量的参考预测块应仍然存有该编码单元的主要特征信息，若色度分量的预测能保持对应亮度分量最优模式下的主要特征信息，则能提高该编码单元的压缩效率。因此本申请技术方案考虑将当前编码单元的亮度分量帧内角度预测的最佳模式作为指导信息，对色度分量的参考预测块的降采样滤波器进行单独设计。
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述。
图9为本申请实施例中所描述的一种实例的视频译码系统1的框图。如本文所使用，术语“视频 译码器”一般是指视频编码器和视频解码器两者。在本申请中，术语“视频译码”或“译码”可一般地指代视频编码或视频解码。视频译码系统1的视频编码器100和视频解码器200用于实时本申请提出的跨分量预测方法。
如图9中所示，视频译码系统1包含源装置10和目的地装置20。源装置10产生经编码视频数据。因此，源装置10可被称为视频编码装置。目的地装置20可对由源装置10所产生的经编码的视频数据进行解码。因此，目的地装置20可被称为视频解码装置。源装置10、目的地装置20或两个的各种实施方案可包含一或多个处理器以及耦合到所述一或多个处理器的存储器。所述存储器可包含但不限于RAM、ROM、EEPROM、快闪存储器或可用于以可由计算机存取的指令或数据结构的形式存储所要的程序代码的任何其它媒体，如本文所描述。
源装置10和目的地装置20可以包括各种装置，包含桌上型计算机、移动计算装置、笔记型(例如，膝上型)计算机、平板计算机、机顶盒、例如所谓的“智能”电话等电话手持机、电视机、相机、显示装置、数字媒体播放器、视频游戏控制台、车载计算机或其类似者。
目的地装置20可经由链路30从源装置10接收经编码视频数据。链路30可包括能够将经编码视频数据从源装置10移动到目的地装置20的一或多个媒体或装置。在一个实例中，链路30可包括使得源装置10能够实时将经编码视频数据直接发射到目的地装置20的一或多个通信媒体。在此实例中，源装置10可根据通信标准(例如无线通信协议)来调制经编码视频数据，且可将经调制的视频数据发射到目的地装置20。所述一或多个通信媒体可包含无线和/或有线通信媒体，例如射频(RF)频谱或一或多个物理传输线。所述一或多个通信媒体可形成基于分组的网络的一部分，基于分组的网络例如为局域网、广域网或全球网络(例如，因特网)。所述一或多个通信媒体可包含路由器、交换器、基站或促使从源装置10到目的地装置20的通信的其它设备。在另一实例中，可将经编码数据从输出接口140输出到存储装置40。
本申请的图像编解码技术可应用于视频编解码以支持多种多媒体应用，例如空中电视广播、有线电视发射、卫星电视发射、串流视频发射(例如，经由因特网)、用于存储于数据存储媒体上的视频数据的编码、存储在数据存储媒体上的视频数据的解码，或其它应用。在一些实例中，视频译码系统1可用于支持单向或双向视频传输以支持例如视频流式传输、视频回放、视频广播和/或视频电话等应用。
图9中所说明的视频译码系统1仅为实例，并且本申请的技术可适用于未必包含编码装置与解码装置之间的任何数据通信的视频译码设置(例如，视频编码或视频解码)。在其它实例中，数据从本地存储器检索、在网络上流式传输等等。视频编码装置可对数据进行编码并且将数据存储到存储器，和/或视频解码装置可从存储器检索数据并且对数据进行解码。在许多实例中，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装置执行编码和解码。
在图9的实例中，源装置10包含视频源120、视频编码器100和输出接口140。在一些实例中，输出接口140可包含调节器/解调器(调制解调器)和/或发射器。视频源120可包括视频捕获装置(例如，摄像机)、含有先前捕获的视频数据的视频存档、用以从视频内容提供者接收视频数据的视频馈入接口，和/或用于产生视频数据的计算机图形系统，或视频数据的此些来源的组合。
视频编码器100可对来自视频源120的视频数据进行编码。在一些实例中，源装置10经由输出接口140将经编码视频数据直接发射到目的地装置20。在其它实例中，经编码视频数据还可存储到存储装置40上，供目的地装置20以后存取来用于解码和/或播放。
在图9的实例中，目的地装置20包含输入接口240、视频解码器200和显示装置220。在一些实例中，输入接口240包含接收器和/或调制解调器。输入接口240可经由链路30和/或从存储装置40接收经编码视频数据。显示装置220可与目的地装置20集成或可在目的地装置20外部。一般来说，显示装置220显示经解码视频数据。显示装置220可包括多种显示装置，例如，液晶显示器(LCD)、等离子显示器、有机发光二极管(OLED)显示器或其它类型的显示装置。
尽管图9中未图示，但在一些方面，视频编码器100和视频解码器200可各自与音频编码器和解码器集成，且可包含适当的多路复用器-多路分用器单元或其它硬件和软件，以处置共同数据流或单独数据流中的音频和视频两者的编码。在一些实例中，如果适用的话，那么MUX-DEMUX单元可符合ITU H.223多路复用器协议，或例如用户数据报协议(UDP)等其它协议。
视频编码器100和视频解码器200各自可实施为例如以下各项的多种电路中的任一者：一或多个微处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现场可编程门阵列(FPGA)、离散逻辑、硬件或其任何组合。如果部分地以软件来实施本申请，那么装置可将用于软件的指令存储在合适的非易失性计算机可读存储媒体中，且可使用一或多个处理器在硬件中执行所述指令从而实施本申请技术。前述内容(包含硬件、软件、硬件与软件的组合等)中的任一者可被视为一或多个处理器。视频编码器 100和视频解码器200中的每一者可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者可集成为相应装置中的组合编码器/解码器(编码解码器)的一部分。
图10为本申请实施例中所描述的一种视频编码器100的示例框图。视频编码器100用于将视频输出到后处理实体41。后处理实体41表示可处理来自视频编码器100的经编码视频数据的视频实体的实例，例如媒体感知网络元件(MANE)或拼接/编辑装置。在一些情况下，后处理实体41可为网络实体的实例。在一些视频编码系统中，后处理实体41和视频编码器100可为单独装置的若干部分，而在其它情况下，相对于后处理实体41所描述的功能性可由包括视频编码器100的相同装置执行。在某一实例中，后处理实体41是图1的存储装置40的实例。
在图10的实例中，视频编码器100包括预测处理单元108、滤波器单元106、经解码图像缓冲器(DPB)107、求和器112、变换器101、量化器102和熵编码器103。预测处理单元108包括帧间预测器110和帧内预测器109。为了图像块重构，视频编码器100还包含反量化器104、反变换器105和求和器111。滤波器单元106表示一或多个环路滤波器，例如去块滤波器、自适应环路滤波器(ALF)和样本自适应偏移(SAO)滤波器。尽管在图10中将滤波器单元106示出为环路内滤波器，但在其它实现方式下，可将滤波器单元106实施为环路后滤波器。在一种示例下，视频编码器100还可以包括视频数据存储器、分割单元(图中未示意)。
视频编码器100接收视频数据，并将所述视频数据存储在视频数据存储器中。分割单元将所述视频数据分割成若干图像块，而且这些图像块可以被进一步分割为更小的块，例如基于四叉树结构或者二叉树结构的图像块分割。预测处理单元108可选择用于当前图像块的多个可能的译码模式中的一者，例如多个帧内译码模式中的一者或多个帧间译码模式中的一者。预测处理单元108可将所得经帧内、帧间译码的块提供给求和器112以产生残差块，且提供给求和器111以重构用作参考图像的经编码块。预测处理单元108内的帧内预测器109可相对于与待编码当前块在相同帧或条带中的一或多个相邻块执行当前图像块的帧内预测性编码，以去除空间冗余。预测处理单元108内的帧间预测器110可相对于一或多个参考图像中的一或多个预测块执行当前图像块的帧间预测性编码以去除时间冗余。预测处理单元108将指示当前图像块的所选帧内或帧间预测模式的信息提供到熵编码器103，以便于熵编码器103编码指示所选帧间预测模式的信息。
在预测处理单元108经由帧间预测、帧内预测产生当前图像块的预测块之后，视频编码器100通过从待编码的当前图像块减去所述预测块来形成残差图像块。求和器112表示执行此减法运算的一或多个组件。所述残差块中的残差视频数据可包含在一或多个TU中，并应用于变换器101。变换器101使用例如离散余弦变换(DCT)或概念上类似的变换等变换将残差视频数据变换成残差变换系数。变换器101可将残差视频数据从像素值域转换到变换域，例如频域。
变换器101可将所得变换系数发送到量化器102。量化器102量化所述变换系数以进一步减小位码率。在一些实例中，量化器102可接着执行对包含经量化的变换系数的矩阵的扫描。或者，熵编码器103可执行扫描。
在量化之后，熵编码器103对经量化变换系数进行熵编码。举例来说，熵编码器103可执行上下文自适应可变长度编码(CAVLC)、上下文自适应二进制算术编码(CABAC)、基于语法的上下文自适应二进制算术编码(SBAC)、概率区间分割熵(PIPE)编码或另一熵编码方法或技术。在由熵编码器103熵编码之后，可将经编码码流发射到视频解码器200，或经存档以供稍后发射或由视频解码器200检索。熵编码器103还可对待编码的当前图像块的语法元素进行熵编码。
反量化器104和反变化器105分别应用逆量化和逆变换以在像素域中重构所述残差块，例如以供稍后用作参考图像的参考块。求和器111将经重构的残差块添加到由帧间预测器110或帧内预测器109产生的预测块，以产生经重构图像块。滤波器单元106可以适用于经重构图像块以减小失真，诸如方块效应(block artifacts)。然后，该经重构图像块作为参考块存储在经解码图像缓冲器107中，可由帧间预测器110用作参考块以对后续视频帧或图像中的块进行帧间预测。
具体的，帧内预测器109可对当前编码单元执行帧内预测，具体执行本申请实施例所提供的图像编码方法。帧内预测器109还可将指示当前编码单元所选帧内预测模式的信息提供到熵编码器103，以便熵编码器103编码指示所选帧内预测模式的信息。
图11为本申请实施例中所描述的一种视频解码器200的示例框图。在图11的实例中，视频解码器200包括熵解码器203、预测处理单元208、反量化器204、反变换器205、求和器211、滤波器单元206以及经解码图像缓冲器207。预测处理单元208可以包括帧间预测器210和帧内预测器209。在一些实例中，视频解码器200可执行大体上与相对于来自图10的视频编码器100描述的编码过程互逆的解码过程。
在解码过程中，视频解码器200从视频编码器100接收表示经编码视频条带的图像块和相关联的 语法元素的经编码视频码流。视频解码器200可从网络实体42接收视频数据，可选的，还可以将所述视频数据存储在视频数据存储器(图中未示意)中。视频数据存储器可存储待由视频解码器200的组件解码的视频数据，例如经编码视频码流。存储在视频数据存储器中的视频数据，例如可从存储装置40、从相机等本地视频源、经由视频数据的有线或无线网络通信或者通过存取物理数据存储媒体而获得。视频数据存储器可作为用于存储来自经编码视频码流的经编码视频数据的经解码图像缓冲器(CPB)。
网络实体42可例如为服务器、MANE、视频编辑器/剪接器，或用于实施上文所描述的技术中的一或多者的其它此装置。网络实体42可包括或可不包括视频编码器，例如视频编码器100。在网络实体42将经编码视频码流发送到视频解码器200之前，网络实体42可实施本申请中描述的技术中的部分。在一些视频解码系统中，网络实体42和视频解码器200可为单独装置的部分，而在其它情况下，相对于网络实体42描述的功能性可由包括视频解码器200的相同装置执行。
视频解码器200的熵解码器203对码流进行熵解码以产生经量化的系数和一些语法元素。熵解码器203将语法元素转发到预测处理单元208。视频解码器200可接收在视频条带层级和/或图像块层级处的语法元素。当视频条带被解码为经帧内解码(I)条带时，预测处理单元208的帧内预测器209基于发信号通知的帧内预测模式和来自当前帧或图像的先前经解码块的数据而产生当前视频条带的图像块的预测块。当视频条带被解码为经帧间解码(即，B或P)条带时，预测处理单元208的帧间预测器210可基于从熵解码器203接收到的语法元素，确定用于对当前视频条带的当前图像块进行解码的帧间预测模式，基于确定的帧间预测模式，对所述当前图像块进行解码(例如执行帧间预测)。
反量化器204将在码流中提供且由熵解码器203解码的经量化变换系数逆量化，即去量化。逆量化过程可包括：使用由视频编码器100针对视频条带中的每个图像块计算的量化参数来确定应施加的量化程度以及同样地确定应施加的逆量化程度。反变换器205将逆变换应用于变换系数，例如逆DCT、逆整数变换或概念上类似的逆变换过程，以便产生像素域中的残差块。
在帧间预测器210产生用于当前图像块或当前图像块的子块的预测块之后，视频解码器200通过将来自反变换器205的残差块与由帧间预测器210产生的对应预测块求和以得到重建的块，即经解码图像块。求和器211表示执行此求和操作的组件。在需要时，还可使用环路滤波器(在解码环路中或在解码环路之后)来使像素转变平滑或者以其它方式改进视频质量。滤波器单元206可以表示一或多个环路滤波器，例如去块滤波器、自适应环路滤波器(ALF)以及样本自适应偏移(SAO)滤波器。尽管在图11中将滤波器单元206示出为环路内滤波器，但在其它实现方式中，可将滤波器单元206实施为环路后滤波器。
应当理解的是，视频解码器200的其它结构变化可用于解码经编码视频码流。例如，视频解码器200可以不经滤波器单元206处理而生成输出视频流；或者，对于某些图像块或者图像帧，视频解码器200的熵解码器203没有解码出经量化的系数，相应地不需要经反量化器204和反变换器205处理。
具体的，帧内预测器209在预测块的产生过程中可以使用本申请实施例所描述的图像解码方法。
图12A为本申请实施例中图像编码方法的一种流程示意图，该图像编码方法可以应用于图9示出的视频译码系统1中的源装置10或图10示出的视频编码器100。图12A示出的流程以执行主体为图10示出的视频编码器100为例进行说明。如图12A所示，本申请实施例提供的跨分量预测方法包括：
步骤110，划分图像，确定当前编码块的亮度分量帧内预测模式和色度分量帧内预测模式。
其中，所述图像所属的视频的颜色格式包括但不限于4:2:0、4:2:2等。
例如，在颜色格式为4:2:0时，如图2中的(C)所示，当前编码块的亮度分量的原始像素块与色度分量的原始像素块的像素比例为4:1，以8*8的正向方像素阵列为例，则对应的亮度分量的原始像素块的尺寸为8*8，则对应的色度分量的原始像素块的尺寸为4*4。
又如，在颜色格式为4:2:2时，如图2中的(B)所示，当前编码单元的亮度分量的原始像素块与色度分量的原始像素块的像素比例为2:1，以8*8的正向方像素阵列为例，则对应的亮度分量的原始像素块的尺寸为8*8，则对应的色度分量的原始像素块的尺寸为8*4。
其中，如图5所示，帧内编码亮度分量计算最多65个帧内预测模式，具体实现中，亮度分量进行最多62个角度预测模式和3个非角度预测模式的计算并选出一个最优帧内预测模式进行传输，而色度分量的帧内预测模式最多进行6个预测模式的计算。所述当前编码块的亮度分量帧内预测模式为多个帧内预测模式中码率失真代价最优的预测模式，所述多个帧内预测模式为所述当前编码块的亮度分量的帧内预测所使用的帧内预测模式。
步骤120，当所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量时，根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块。
具体实现中，设备可以在判断出所述亮度分量帧内预测模式为预设帧内预测模式的情况下，确定 所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量。所述预设帧内预测模式为预设方向的亮度分量帧内预测模式，该预设方向包括但不限于水平方向(例如：如图1所述的二维直角坐标系XoY中沿X轴方向)、垂直方向(例如：如图1所示的二维直角坐标系XoY中沿Y轴负向方向)以及对角线方向(例如：如图1所示的二维直角坐标系XoY中沿X轴负45度角度方向)。
步骤130，对所述当前编码块的色度分量的参考预测块进行滤波，得到所述当前编码块的色度分量的预测块。
具体实现中，当前编码块的色度分量的预测块确定后，设备可以进一步计算出色度分量的重构块，根据色度分量的重构块和亮度分量的重构块确定当前编码块的重构图像块。
可见，本申请实施例中，相比于现有技术，本申请方案利用在跨分量预测模式中实现对当前编码块的色度分量的参考预测块进行滤波，有利于提高编码块的压缩效率，从而提高编码效率。
在一个可能的示例中，所述对所述当前编码块的色度分量的参考预测块进行滤波，包括：根据所述亮度分量帧内预测模式确定滤波器；使用所述滤波器对所述当前编码块的色度分量的参考预测块进行滤波。
具体实现中，设备根据所述亮度分量帧内预测模式所指示的帧内预测方向确定滤波器。
例如，针对竖向图像特征(如竖直条状图像)比较突出的视频中的一帧图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的竖向的方向强度，从而达到更好的预测效果。
又如，针对水平方向图像特征(如水平条状图像)比较突出的视频中的一帧图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的水平方向的方向强度，从而达到更好的预测效果。
又例如，针对图像对角线方向图像特征(如对角线条状图像)比较突出的视频中的一帧图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的对角线方向的方向强度，从而达到更好的预测效果。
可见，本示例中，通过亮度分量帧内预测模式确定滤波器，并使用该滤波器对色度分量的参考预测块进行滤波，从而使得色度分量的预测能保持对应亮度分量最优模式下的主要特征信息，即图像内容的主要特征信息在亮度分量和色度分量中保持较高的一致性，有利于提高该编码块的压缩效率，达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式确定滤波器，包括：当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第一滤波器。
在本可能的示例中，所述第一滤波器包括用于对所述色度分量的参考预测块的上边界像素区域进行滤波的第一两抽头滤波器和用于对所述色度分量的参考预测块的非上边界像素区域进行滤波的第一三抽头滤波器。
在本可能的示例中，所述第一两抽头滤波器包括：
Figure PCTCN2021081132-appb-000008
Figure PCTCN2021081132-appb-000009
Figure PCTCN2021081132-appb-000010
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000011
和
Figure PCTCN2021081132-appb-000012
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000013
表示取
Figure PCTCN2021081132-appb-000014
和
Figure PCTCN2021081132-appb-000015
中的较大值。
在本可能的示例中，所述第一三抽头滤波器包括：
Figure PCTCN2021081132-appb-000016
Figure PCTCN2021081132-appb-000017
Figure PCTCN2021081132-appb-000018
或者，所述第一三抽头滤波器包括：
Figure PCTCN2021081132-appb-000019
Figure PCTCN2021081132-appb-000020
Figure PCTCN2021081132-appb-000021
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000022
和
Figure PCTCN2021081132-appb-000023
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000024
表示取
Figure PCTCN2021081132-appb-000025
和
Figure PCTCN2021081132-appb-000026
中的较大值。
举例来说，如图12B所示的在8*8像素阵列中水平方向的降采样过程，x2表示乘以2，x3表示乘以3，以色度分量的参考预测块中的第一行和第二行像素为例，首先，针对像素a、像素b、像素i、像素i使用第一两抽头滤波器进行降采样形成色度分量的预测块的像素1，然后，在水平方向上，针对像素b、像素c、像素d、像素j、像素k和像素l，使用第一三抽头滤波器进行降采样形成色度分量的预测块的像素2，其次，按照步长2跳转，针对像素d、像素e、像素f、像素l、像素m和像素n，使用第一三抽头滤波器进行降采样形成色度分量的预测块的像素3，再次，按照步长2跳转，针对像素f、像素g、像素h、像素n、像素o和像素p，使用第一三抽头滤波器进行降采样形成色度分量的预测块的像素4，其他列以此类推。
可见，本示例中，针对水平方向图像特征(如水平条状图像)比较突出的视频中的图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的水平方向的方向强度，从而达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式确定滤波器，包括：当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第二滤波器。
在本可能的示例中，所述第二滤波器包括用于对所述色度分量的参考预测块的左边界像素区域进行滤波的第二两抽头滤波器和用于对所述色度分量的参考预测块的非左边界像素区域进行滤波的第二三抽头滤波器。
在本可能的示例中，所述第二两抽头滤波器包括：
Figure PCTCN2021081132-appb-000027
Figure PCTCN2021081132-appb-000028
Figure PCTCN2021081132-appb-000029
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000030
和
Figure PCTCN2021081132-appb-000031
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000032
表示取
Figure PCTCN2021081132-appb-000033
和
Figure PCTCN2021081132-appb-000034
中的较大值。
在本可能的示例中，所述第二三抽头滤波器包括：
Figure PCTCN2021081132-appb-000035
Figure PCTCN2021081132-appb-000036
Figure PCTCN2021081132-appb-000037
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000038
和
Figure PCTCN2021081132-appb-000039
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000040
表示取
Figure PCTCN2021081132-appb-000041
和
Figure PCTCN2021081132-appb-000042
中的较大值。
举例来说，如图12C所示的在8*8像素阵列中的垂直方向的降采样过程，x2表示乘以2，x3表示乘以3，以色度分量的参考预测块中的第一列和第二列像素为例，首先，针对像素a、像素b、像素c、像素d使用第二两抽头滤波器进行降采样形成亮度分量的预测块的像素1，然后，在垂直方向上，针对像素c、像素d、像素e、像素f、像素g和像素h，使用第二三抽头滤波器进行降采样形成色度分量的预测块的像素2，其次，按照步长2跳转，针对像素g、像素h、像素i、像素j、像素k和像素l，使用第二三抽头滤波器进行降采样形成色度分量的预测块的像素3，再次，按照步长2跳转，针对像素k、像素l、像素m、像素n、像素o和像素p，使用第二三抽头滤波器进行降采样形成色度分量的预测块的像素4，其他列以此类推。
可见，本示例中，针对竖向图像特征(如竖直条状图像)比较突出的视频中的图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的竖向的方向强度，从而达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式为所述当前解码块选择滤波器，包括：当所述亮度分量帧内预测模式所指示的帧内预测方向是对角线方向时，所述滤波器设置为第三滤波器。
在本可能的示例中，所述第三滤波器包括用于对所述色度分量参考预测块的左边界像素区域和上边界像素区域进行滤波的第三两抽头滤波器和用于对所述色度分量参考预测块的除左边界像素区域和上边界像素区域之外的像素区域进行滤波的第三三抽头滤波器。
在本可能的示例中，所述第三两抽头滤波器包括：
P C＝(P′ C(2x,2y)+P′ C(2x+1,2y+1)+1)>>1；
其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
在本可能的示例中，所述第三三抽头滤波器包括：
P C＝(3×P′ C(2x,2y)+3×P′ C(2x+1,2y+1)+2×P′ C(2x-1,2y-1)+4)>>3；
其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
举例来说，如图12D所示的在8*8像素阵列中的垂直方向的降采样过程，x2表示乘以2，x3表示乘以3，以色度分量的参考预测块中对角线方向的像素为例，首先，针对像素a、像素b、像素c、像素d使用第三两抽头滤波器进行降采样形成亮度分量的预测块的像素1，然后，在对角线方向上，针对像素d、像素e、像素f、像素g、像素h、像素i、像素j、像素k、像素l，使用第三三抽头滤波器进行降采样形成色度分量的预测块的像素2，其次，按照步长2跳转，针对像素l、像素m、像素n、像素o、像素p、像素q、像素r、像素s、像素t，使用三抽头两个不同系数的滤波器进行降采样并取大值形成色度分量的预测块的像素3，再次，按照步长2跳转，针对像素t、像素u、像素v、像素w、像素x、像素y、像素z、像素A、像素B，使用第三三抽头滤波器进行降采样形成色度分量的预测块的像素4，其他列以此类推。
可见，本示例中，针对图像对角线方向图像特征(如对角线条状图像)比较突出的视频中的图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的对角线方向的方向强度，从而达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块，包括：根据所述亮度分量帧内预测模式，确定所述当前编码块的亮度分量的重构块；根据所述当前编码块的亮度分量的重构块，确定所述当前编码块的色度分量的参考预测块。
其中，所述色度分量的参考预测块的尺寸与所述亮度分量的重构块的尺寸相同。例如如图8所示的预测过程中的亮度分量的重构块和色度分量的参考预测块均为8*8像素阵列。
在本可能的示例中，所述根据所述当前编码块的亮度分量的重构块，确定所述当前编码块的色度分量的参考预测块，包括：确定利用所述当前编码块的亮度分量的重构块进行跨分量预测的线性模型；根据所述线性模型计算所述亮度分量的重构块，得到所述当前编码块的色度分量的参考预测块。
其中，所述线性模型例如可以是前述公式(1)的线性模型。
在本可能的示例中，所述确定利用所述当前编码块的亮度分量的重构块进行跨分量预测的线性模型，包括：确定用于计算所述线性模型的参考像素，所述参考像素包括所述当前编码块的至少一个相邻像素；根据所述参考像素计算所述线性模型。
可选的，若当前编码块为当前编码单元中的部分图像块，则设备可以从多个线性模型中选择适配所述当前编码块的线性模型，具体可以根据图像特性针对当前编码块选择适配的线性模型，由于该线性模型的系数还未确定，还需要根据参考像素进行计算得到。可见，设备针对当前编码块的色度分量预测，能够提供相对于编码单元更加精细化的预测机制，实现更精细化的图像预测。
在本可能的示例中，所述确定用于计算所述线性模型的参考像素，包括：根据所述当前编码块的相邻像素的重构样本的可用信息和所述色度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
其中，所述当前编码块的色度分量的帧内预测模式包括TSCPM、TSCPM_T、TSCPM_L中的任意一种。所述可用信息具体包括两侧可用和单侧可用(例如：左侧可用和右侧可用)。下面进行详细说明。
若当前编码块的色度分量的帧内预测模式为TSCPM，且可用信息为当前编码块对应的原始像素块的上侧相邻像素的重构样本和当前编码块的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的上侧相邻像素中的2个和左侧相邻像素中的2个， 如图6中(a)所示。
若当前编码块的色度分量的帧内预测模式为TSCPM，且可用信息为当前编码块对应的原始像素块的上侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的上侧相邻像素中的4个，如图6中(b)所示。
若当前编码块的色度分量的帧内预测模式为TSCPM，且可用信息为当前编码块对应的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的做侧相邻像素中的4个，如图6中(c)所示。
若当前编码块的色度分量的帧内预测模式为TSCPM_T，且当前编码块对应的原始像素块的上侧相邻像素的重构样本和当前编码块对应的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的上侧相邻像素中的4个，如图6中(b)所示。
若当前编码块的色度分量的帧内预测模式为TSCPM_L，且当前编码块对应的原始像素块的上侧相邻像素的重构样本和当前编码块对应的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的做侧相邻像素中的4个，如图6中(c)所示。
可见，本示例中，用于计算线性模型的系数的参考相邻像素可以根据相邻像素的重构样本的可用性和色度分量的帧内预测模式进行灵活设置。
在本可能的示例中，所述确定用于计算所述线性模型的参考像素，包括：根据所述当前编码块的相邻编码块的码率失真代价最优的亮度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
其中，所述相邻编码块的亮度分量的码率失真代价最优的帧内预测模式可以与当前编码单元的亮度分量的码率失真代价最优的帧内预测模式相同，也可能不同。
与图12A所述的图像编码方法对应的，图13为本申请实施例中图像编码方法的一种流程示意图，该图像编码方法可以应用于图9示出的视频译码系统1中的目的装置20或图11示出的视频解码器200。图13示出的流程以执行主体为图11示出的视频编码器200为例进行说明。如图13所示，本申请实施例提供的跨分量预测方法包括：
步骤210，解析码流，确定当前解码块的亮度分量帧内预测模式和色度分量帧内预测模式。
其中，所述码流的视频的颜色格式包括但不限于4:2:0、4:2:2等。
具体实现中，所述码流经过熵解码可以获取到语法元素，该语法元素用于确定对当前解码块进行预测的亮度分量帧内预测模式和色度分量帧内预测模式。其中，所述亮度分量帧内预测模式为多个帧内预测模式中的最优亮度分量帧内预测模式，多个帧内预测模式为亮度分量的帧内预测所使用的帧内预测模式。
步骤220，当所述色度分量帧内预测模式指示使用所述当前解码块的亮度分量的重构块推导所述当前解码块的色度分量的预测值时，根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块。
具体实现中，设备可以在判断出所述亮度分量帧内预测模式为预设帧内预测模式的情况下，确定所述色度分量帧内预测模式指示使用所述当前解码块的亮度分量推导所述当前解码块的色度分量。所述预设帧内预测模式为预设方向的亮度分量帧内预测模式，该预设方向包括但不限于水平方向(例如：如图1所述的二维直角坐标系XoY中沿X轴方向)、垂直方向(例如：如图1所示的二维直角坐标系XoY中沿Y轴负向方向)以及对角线方向(例如：如图1所示的二维直角坐标系XoY中沿X轴负45度角度方向)。
步骤230，对所述当前解码块的色度分量的参考预测块进行滤波，得到所述当前解码块的色度分量的预测块。
具体实现中，当前解码块的色度分量的预测块确定后，设备可以进一步计算出色度分量的重构块，根据色度分量的重构块和亮度分量的重构块确定当前解码块的重构图像。
可以看出，本申请实施例中，相比于现有技术，本申请方案利用在跨分量预测模式中实现对当前解码块的色度分量的参考预测块进行滤波，有利于提高解码块的压缩效率，从而提高解码效率。
在一个可能的示例中，所述对所述当前解码块的色度分量的参考预测块进行滤波，包括：根据所述亮度分量帧内预测模式确定滤波器；使用所述滤波器对所述当前解码块的色度分量的参考预测块进行滤波。
具体实现中，设备根据所述亮度分量帧内预测模式所指示的帧内预测方向确定滤波器。
可见，本示例中，通过亮度分量帧内预测模式确定滤波器，并使用该滤波器对色度分量的参考解码块进行滤波，从而使得色度分量的预测能保持对应亮度分量最优模式下的主要特征信息，即图像内容的主要特征信息在亮度分量和色度分量中保持较高的一致性，有利于提高该解码块的解码效率，达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式确定滤波器，包括：当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第一滤波器。
在本可能的示例中，所述第一滤波器包括用于对所述色度分量的参考预测块的上边界像素区域进行滤波的第一两抽头滤波器和用于对所述色度分量的参考预测块的非上边界像素区域进行滤波的第一三抽头滤波器。
在本可能的示例中，所述第一两抽头滤波器包括：
Figure PCTCN2021081132-appb-000043
Figure PCTCN2021081132-appb-000044
Figure PCTCN2021081132-appb-000045
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000046
和
Figure PCTCN2021081132-appb-000047
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000048
表示取
Figure PCTCN2021081132-appb-000049
和
Figure PCTCN2021081132-appb-000050
中的较大值。
在本可能的示例中，所述第一三抽头滤波器包括：
Figure PCTCN2021081132-appb-000051
Figure PCTCN2021081132-appb-000052
Figure PCTCN2021081132-appb-000053
或者，所述第一三抽头滤波器包括：
Figure PCTCN2021081132-appb-000054
Figure PCTCN2021081132-appb-000055
Figure PCTCN2021081132-appb-000056
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000057
和
Figure PCTCN2021081132-appb-000058
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000059
表示取
Figure PCTCN2021081132-appb-000060
和
Figure PCTCN2021081132-appb-000061
中的较大值。
可见，本示例中，针对水平方向图像特征(如水平条状图像)比较突出的视频中的图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的水平方向的方向强度，从而达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式确定滤波器，包括：当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第二滤波器。
在本可能的示例中，所述第二滤波器包括用于对所述色度分量的参考预测块的左边界像素区域进行滤波的第二两抽头滤波器和用于对所述色度分量的参考预测块的非左边界像素区域进行滤波的第二三抽头滤波器。
在本可能的示例中，所述第二两抽头滤波器包括：
Figure PCTCN2021081132-appb-000062
Figure PCTCN2021081132-appb-000063
Figure PCTCN2021081132-appb-000064
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000065
和
Figure PCTCN2021081132-appb-000066
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000067
表示取
Figure PCTCN2021081132-appb-000068
和
Figure PCTCN2021081132-appb-000069
中的较大值。
在本可能的示例中，所述第二三抽头滤波器包括：
Figure PCTCN2021081132-appb-000070
Figure PCTCN2021081132-appb-000071
Figure PCTCN2021081132-appb-000072
其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
Figure PCTCN2021081132-appb-000073
和
Figure PCTCN2021081132-appb-000074
为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
Figure PCTCN2021081132-appb-000075
表示取
Figure PCTCN2021081132-appb-000076
和
Figure PCTCN2021081132-appb-000077
中的较大值。
可见，本示例中，针对竖向图像特征(如竖直条状图像)比较突出的视频中的图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的竖向的方向强度，从而达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式为所述当前解码块选择滤波器，包括：当所述亮度分量帧内预测模式所指示的帧内预测方向是对角线方向时，所述滤波器设置为第三滤波器。
在本可能的示例中，所述第三滤波器包括用于对所述色度分量参考预测块的左边界像素区域和上边界像素区域进行滤波的第三两抽头滤波器和用于对所述色度分量参考预测块的除左边界像素区域和上边界像素区域之外的像素区域进行滤波的第三三抽头滤波器。
在本可能的示例中，所述第三两抽头滤波器包括：
P C＝(P′ C(2x,2y)+P′ C(2x+1,2y+1)+1)>>1；
其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
在本可能的示例中，所述第三三抽头滤波器包括：
P C＝(3×P′ C(2x,2y)+3×P′ C(2x+1,2y+1)+2×P′ C(2x-1,2y-1)+4)>>3；
其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
可见，本示例中，针对图像对角线方向图像特征(如对角线条状图像)比较突出的视频中的图像，利用亮度分量的最优帧内预测模式指导色度分量的降采样操作，可以增加相对应色度分量的对角线方向的方向强度，从而达到更好的预测效果。
在一个可能的示例中，所述根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块，包括：根据所述色度分量帧内预测模式，确定所述当前解码块的亮度分量的重构块；根据所述当前解码块的亮度分量的重构块，确定所述当前解码块的色度分量的参考预测块。
其中，所述色度分量的参考预测块的尺寸与所述亮度分量的重构块的尺寸相同。例如如图8所示的预测过程中的亮度分量的重构块和色度分量的参考预测块均为8*8像素阵列。
在本可能的示例中，所述根据所述当前解码块的亮度分量的重构块，确定所述当前解码块的色度分量的参考预测块，包括：确定利用所述当前解码块的亮度分量的重构块进行跨分量预测的线性模型；根据所述线性模型计算所述亮度分量的重构块，得到所述当前解码块的色度分量的参考预测块。
其中，所述线性模型例如可以是前述公式(1)的线性模型。
在本可能的示例中，所述确定利用所述当前解码块的亮度分量的重构块进行跨分量预测的线性模型，包括：确定用于计算所述线性模型的参考像素，所述参考像素包括所述当前解码块的至少一个相邻像素；根据所述参考像素计算所述线性模型。
可选的，若当前解码块为当前编码单元中的部分图像块，则设备可以从多个线性模型中选择适配所述当前解码块的线性模型，具体可以根据图像特性针对当前解码块选择适配的线性模型，由于该线性模型的系数还未确定，还需要根据参考像素进行计算得到。可见，设备针对当前解码块的色度分量预测，能够提供相对于编码单元更加精细化的预测机制，实现更精细化的图像预测。
在本可能的示例中，所述确定用于计算所述线性模型的参考像素，包括：根据所述当前解码块的相邻像素的重构样本的可用信息和所述色度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
其中，所述当前解码块的色度分量的帧内预测模式包括TSCPM、TSCPM_T、TSCPM_L中的任意一种。所述可用信息具体包括两侧可用和单侧可用(例如：左侧可用和右侧可用)。
其中，所述当前解码块的色度分量的帧内预测模式包括TSCPM、TSCPM_T、TSCPM_L中的任意一种。所述可用信息具体包括两侧可用和单侧可用(例如：左侧可用和右侧可用)。下面进行详细说明。
若当前解码块的色度分量的帧内预测模式为TSCPM，且可用信息为当前解码块对应的原始像素 块的上侧相邻像素的重构样本和当前解码块的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的上侧相邻像素中的2个和左侧相邻像素中的2个，如图6中(a)所示。
若当前解码块的色度分量的帧内预测模式为TSCPM，且可用信息为当前解码块对应的原始像素块的上侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的上侧相邻像素中的4个，如图6中(b)所示。
若当前解码块的色度分量的帧内预测模式为TSCPM，且可用信息为当前解码块对应的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的做侧相邻像素中的4个，如图6中(c)所示。
若当前解码块的色度分量的帧内预测模式为TSCPM_T，且当前解码块对应的原始像素块的上侧相邻像素的重构样本和当前解码块对应的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的上侧相邻像素中的4个，如图6中(b)所示。
若当前解码块的色度分量的帧内预测模式为TSCPM_L，且当前解码块对应的原始像素块的上侧相邻像素的重构样本和当前解码块对应的原始像素块的左侧相邻像素的重构样本可用，则用于计算线性模型的系数的参考相邻像素为原始像素块的做侧相邻像素中的4个，如图6中(c)所示。
可见，本示例中，用于计算线性模型的系数的参考相邻像素可以根据相邻像素的重构样本的可用性和色度分量的帧内预测模式进行灵活设置。
在本可能的示例中，所述确定用于计算所述线性模型的参考像素，包括：根据所述当前解码块的相邻解码块的码率失真代价最优的亮度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
其中，所述相邻解码块的亮度分量的帧内预测模式可以与当前解码单元的亮度分量的帧内预测模式相同，也可能不同。
数字视频编解码技术在衡量性能指标上主要采用编码比特率(bitrate)以及峰值信噪比(PSNR)进行比较，本申请方案测试实验在AVS3的参考软件High-Performance Model(HPM)，通用测试条件common test condition(CTC)下进行，表1概述了测试的所有帧内(All Intra,AI)配置的仿真结果。
表1
Figure PCTCN2021081132-appb-000078
从表格中可以看出，在Y分量没有损失的情况下，UV分量均有编码增益，U-BDBR和V-BDBR分别有0.05％及0.19％的增益gain。
本申请实施例提供一种图像编码装置，该图像编码装置可以为视频解码器或视频编码器。具体的，图像编码装置用于执行以上解码方法中的视频解码器所执行的步骤。本申请实施例提供的图像编码装置可以包括相应步骤所对应的模块。
本申请实施例可以根据上述方法示例对图像编码装置进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。本申请实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
在采用对应各个功能划分各个功能模块的情况下，图14示出上述实施例中所涉及的图像编码装置的一种可能的结构示意图。如图14所示，图像编码装置14包括划分单元140、确定单元141、滤波单元142。
划分单元140，用于划分图像，确定当前编码块的亮度分量帧内预测模式和色度分量帧内预测模式；
确定单元141，用于当所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量时，根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块；
滤波单元142，用于对所述当前编码块的色度分量的参考预测块进行滤波，得到所述当前编码块 的色度分量的预测块。
其中，上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。当然，本申请实施例提供的图像编码装置包括但不限于上述模块，例如：图像编码装置还可以包括存储单元143。存储单元143可以用于存储该图像编码装置的程序代码和数据。
在采用集成的单元的情况下，本申请实施例提供的图像编码装置的结构示意图如图15所示。在图15中，图像编码装置15包括：处理模块150和通信模块151。处理模块150用于对图像编码装置的动作进行控制管理，例如，执行划分单元140、确定单元141、滤波单元142执行的步骤，和/或用于执行本文所描述的技术的其它过程。通信模块151用于支持图像编码装置与其他设备之间的交互。如图15所示，图像编码装置还可以包括存储模块152，存储模块152用于存储图像编码装置的程序代码和数据，例如存储上述存储单元143所保存的内容。
其中，处理模块150可以是处理器或控制器，例如可以是中央处理器(Central Processing Unit，CPU)，通用处理器，数字信号处理器(Digital Signal Processor，DSP)，ASIC，FPGA或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本申请公开内容所描述的各种示例性的逻辑方框，模块和电路。所述处理器也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，DSP和微处理器的组合等等。通信模块151可以是收发器、RF电路或通信接口等。存储模块152可以是存储器。
其中，上述方法实施例涉及的各场景的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。上述图像编码装置14和图像编码装置15均可执行上述图12A所示的图像编码方法，图像编码装置14和图像编码装置15具体可以是视频图像编码装置或者其他具有视频编码功能的设备。
本申请还提供一种视频编码器，包括非易失性存储介质，以及中央处理器，所述非易失性存储介质存储有可执行程序，所述中央处理器与所述非易失性存储介质连接，并执行所述可执行程序以实现本申请实施例的图像编码方法。
本申请实施例提供一种图像解码装置，该图像解码装置可以为视频解码器或视频解码器。具体的，图像解码装置用于执行以上解码方法中的视频解码器所执行的步骤。本申请实施例提供的图像解码装置可以包括相应步骤所对应的模块。
本申请实施例可以根据上述方法示例对图像解码装置进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。本申请实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
在采用对应各个功能划分各个功能模块的情况下，图16示出上述实施例中所涉及的图像解码装置的一种可能的结构示意图。如图16所示，图像解码装置16包括解析单元160、确定单元161、滤波单元162。
解析单元160，用于解析码流，确定当前解码块的亮度分量帧内预测模式和色度分量帧内预测模式；
确定单元161，用于当所述色度分量帧内预测模式指示使用所述当前解码块的亮度分量的重构块推导所述当前解码块的色度分量的预测值时，根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块；
滤波单元162，用于对所述当前解码块的色度分量的参考预测块进行滤波，得到所述当前解码块的色度分量的预测块。
其中，上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。当然，本申请实施例提供的图像解码装置包括但不限于上述模块，例如：图像解码装置还可以包括存储单元163。存储单元163可以用于存储该图像解码装置的程序代码和数据。
在采用集成的单元的情况下，本申请实施例提供的图像解码装置的结构示意图如图17所示。在图17中，图像解码装置17包括：处理模块170和通信模块171。处理模块170用于对图像解码装置的动作进行控制管理，例如，执行解析单元160、确定单元161、滤波单元162执行的步骤，和/或用于执行本文所描述的技术的其它过程。通信模块171用于支持图像解码装置与其他设备之间的交互。如图15所示，图像解码装置还可以包括存储模块172，存储模块172用于存储图像解码装置的程序代码和数据，例如存储上述存储单元163所保存的内容。
其中，处理模块170可以是处理器或控制器，例如可以是中央处理器(Central Processing Unit，CPU)，通用处理器，数字信号处理器(Digital Signal Processor，DSP)，ASIC，FPGA或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本申请公开内容所描述的各种示例性的逻辑方框，模块和电路。所述处理器也可以是实现计算功能的组合，例如包含一 个或多个微处理器组合，DSP和微处理器的组合等等。通信模块171可以是收发器、RF电路或通信接口等。存储模块172可以是存储器。
其中，上述方法实施例涉及的各场景的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。上述图像解码装置16和图像解码装置17均可执行上述图13所示的图像解码方法，图像解码装置16和图像解码装置17具体可以是视频图像解码装置或者其他具有视频解码功能的设备。
本申请还提供一种视频解码器，包括非易失性存储介质，以及中央处理器，所述非易失性存储介质存储有可执行程序，所述中央处理器与所述非易失性存储介质连接，并执行所述可执行程序以实现本申请实施例的图像解码方法。
本申请还提供一种终端，该终端包括：一个或多个处理器、存储器、通信接口。该存储器、通信接口与一个或多个处理器耦合；存储器用于存储计算机程序代码，计算机程序代码包括指令，当一个或多个处理器执行指令时，终端执行本申请实施例的图像编码和/或或图像解码方法。这里的终端可以是视频显示设备，智能手机，便携式电脑以及其它可以处理视频或者播放视频的设备。
本申请另一实施例还提供一种计算机可读存储介质，该计算机可读存储介质包括一个或多个程序代码，该一个或多个程序包括指令，当解码设备中的处理器在执行该程序代码时，该解码设备执行本申请实施例的图像编码方法、图像解码方法。
在本申请的另一实施例中，还提供一种计算机程序产品，该计算机程序产品包括计算机执行指令，该计算机执行指令存储在计算机可读存储介质中；解码设备的至少一个处理器可以从计算机可读存储介质读取该计算机执行指令，至少一个处理器执行该计算机执行指令使得终端实施执行本申请实施例的图像编码方法、图像解码方法。
在上述实施例中，可以全部或部分的通过软件，硬件，固件或者其任意组合来实现。当使用软件程序实现时，可以全部或部分地以计算机程序产品的形式出现。所述计算机程序产品包括一个或多个计算机指令。在计算机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。
所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。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(例如同轴电缆、光纤、数字用户线(DSL))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、服务器或数据中心传输。所述计算机可读存储介
质可以是计算机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。该可用介质可以是磁性介质，(例如，软盘，硬盘、磁带)、光介质(例如，DVD)或者半导体介质(例如固态硬盘Solid State Disk(SSD))等。
通过以上的实施方式的描述，所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，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。
在本申请所提供的几个实施例中，应该理解到，所揭露的装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述模块或单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个装置，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是一个物理单元或多个物理单元，即可以位于一个地方，或者也可以分布到多个不同地方。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
所述集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个可读取存储介质中。基于这样的理解，本申请实施例的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来，该软件产品存储在一个存储介质中，包括若干指令用以使得一个设备(可以是单片机，芯片等)或处理器(processor)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何在本申请揭露的技术范围内的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (47)

  1. 一种图像编码方法，其特征在于，包括：
    划分图像，确定当前编码块的亮度分量帧内预测模式和色度分量帧内预测模式；
    当所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量时，根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块；
    对所述当前编码块的色度分量的参考预测块进行滤波，得到所述当前编码块的色度分量的预测块。
  2. 根据权利要求1所述的方法，其特征在于，所述对所述当前编码块的色度分量的参考预测块进行滤波，包括：
    根据所述亮度分量帧内预测模式确定滤波器；
    使用所述滤波器对所述当前编码块的色度分量的参考预测块进行滤波。
  3. 根据权利要求2所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式确定滤波器，包括：
    当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第一滤波器。
  4. 根据权利要求3所述的方法，其特征在于，所述第一滤波器包括用于对所述色度分量的参考预测块的上边界像素区域进行滤波的第一两抽头滤波器和用于对所述色度分量的参考预测块的非上边界像素区域进行滤波的第一三抽头滤波器。
  5. 根据权利要求4所述的方法，其特征在于，所述第一两抽头滤波器包括：
    Figure PCTCN2021081132-appb-100001
    Figure PCTCN2021081132-appb-100002
    Figure PCTCN2021081132-appb-100003
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100004
    和
    Figure PCTCN2021081132-appb-100005
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100006
    表示取
    Figure PCTCN2021081132-appb-100007
    和
    Figure PCTCN2021081132-appb-100008
    中的较大值。
  6. 根据权利要求5所述的方法，其特征在于，所述第一三抽头滤波器包括：
    Figure PCTCN2021081132-appb-100009
    Figure PCTCN2021081132-appb-100010
    Figure PCTCN2021081132-appb-100011
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100012
    和
    Figure PCTCN2021081132-appb-100013
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100014
    表示取
    Figure PCTCN2021081132-appb-100015
    和
    Figure PCTCN2021081132-appb-100016
    中的较大值。
  7. 根据权利要求2所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式确定滤波器，包括：
    当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第二滤波器。
  8. 根据权利要求7所述的方法，其特征在于，所述第二滤波器包括用于对所述色度分量的参考预测块的左边界像素区域进行滤波的第二两抽头滤波器和用于对所述色度分量的参考预测块的非左边界像素区域进行滤波的第二三抽头滤波器。
  9. 根据权利要求8所述的方法，其特征在于，所述第二两抽头滤波器包括：
    Figure PCTCN2021081132-appb-100017
    Figure PCTCN2021081132-appb-100018
    Figure PCTCN2021081132-appb-100019
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100020
    和
    Figure PCTCN2021081132-appb-100021
    为所述当 前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100022
    表示取
    Figure PCTCN2021081132-appb-100023
    和
    Figure PCTCN2021081132-appb-100024
    中的较大值。
  10. 根据权利要求9所述的方法，其特征在于，所述第二三抽头滤波器包括：
    Figure PCTCN2021081132-appb-100025
    Figure PCTCN2021081132-appb-100026
    Figure PCTCN2021081132-appb-100027
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100028
    和
    Figure PCTCN2021081132-appb-100029
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100030
    表示取
    Figure PCTCN2021081132-appb-100031
    和
    Figure PCTCN2021081132-appb-100032
    中的较大值。
  11. 根据权利要求2所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式为所述当前解码块选择滤波器，包括：
    当所述亮度分量帧内预测模式所指示的帧内预测方向是对角线方向时，所述滤波器设置为第三滤波器。
  12. 根据权利要求11所述的方法，其特征在于，所述第三滤波器包括用于对所述色度分量参考预测块的左边界像素区域和上边界像素区域进行滤波的第三两抽头滤波器和用于对所述色度分量参考预测块的除左边界像素区域和上边界像素区域之外的像素区域进行滤波的第三三抽头滤波器。
  13. 根据权利要求12所述的方法，其特征在于，所述第三两抽头滤波器包括：
    P C＝(P′ C(2x,2y)+P′ C(2x+1,2y+1)+1)>>1；
    其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
  14. 根据权利要求13所述的方法，其特征在于，所述第三三抽头滤波器包括：
    P C＝(3×P′ C(2x,2y)+3×P′ C(2x+1,2y+1)+2×P′ C(2x-1,2y-1)+4)>>3；
    其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
  15. 根据权利要求1-14任一项所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块，包括：
    根据所述亮度分量帧内预测模式，确定所述当前编码块的亮度分量的重构块；
    根据所述当前编码块的亮度分量的重构块，确定所述当前编码块的色度分量的参考预测块。
  16. 根据权利要求15所述的方法，其特征在于，所述根据所述当前编码块的亮度分量的重构块，确定所述当前编码块的色度分量的参考预测块，包括：
    确定利用所述当前编码块的亮度分量的重构块进行跨分量预测的线性模型；
    根据所述线性模型计算所述亮度分量的重构块，得到所述当前编码块的色度分量的参考预测块。
  17. 根据权利要求16所述的方法，其特征在于，所述确定利用所述当前编码块的亮度分量的重构块进行跨分量预测的线性模型，包括：
    确定用于计算所述线性模型的参考像素，所述参考像素包括所述当前编码块的至少一个相邻像素；
    根据所述参考像素计算所述线性模型。
  18. 根据权利要求17所述的方法，其特征在于，所述确定用于计算所述线性模型的参考像素，包括：
    根据所述当前编码块的相邻像素的重构样本的可用信息和所述色度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
  19. 根据权利要求17所述的方法，其特征在于，所述确定用于计算所述线性模型的参考像素，包括：
    根据所述当前编码块的相邻编码块的码率失真代价最优的亮度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
  20. 根据权利要求5所述的方法，其特征在于，所述第一三抽头滤波器包括：
    Figure PCTCN2021081132-appb-100033
    Figure PCTCN2021081132-appb-100034
    Figure PCTCN2021081132-appb-100035
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100036
    和
    Figure PCTCN2021081132-appb-100037
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100038
    表示取
    Figure PCTCN2021081132-appb-100039
    和
    Figure PCTCN2021081132-appb-100040
    中的较大值。
  21. 一种图像解码方法，其特征在于，包括：
    解析码流，确定当前解码块的亮度分量帧内预测模式和色度分量帧内预测模式；
    当所述色度分量帧内预测模式指示使用所述当前解码块的亮度分量的重构块推导所述当前解码块的色度分量的预测值时，根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块；
    对所述当前解码块的色度分量的参考预测块进行滤波，得到所述当前解码块的色度分量的预测块。
  22. 根据权利要求21所述的方法，其特征在于，所述对所述当前解码块的色度分量的参考预测块进行滤波，包括：
    根据所述亮度分量帧内预测模式确定滤波器；
    使用所述滤波器对所述当前解码块的色度分量的参考预测块进行滤波。
  23. 根据权利要求22所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式确定滤波器，包括：
    当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第一滤波器。
  24. 根据权利要求23所述的方法，其特征在于，所述第一滤波器包括用于对所述色度分量的参考预测块的上边界像素区域进行滤波的第一两抽头滤波器和用于对所述色度分量的参考预测块的非上边界像素区域进行滤波的第一三抽头滤波器。
  25. 根据权利要求24所述的方法，其特征在于，所述第一两抽头滤波器包括：
    Figure PCTCN2021081132-appb-100041
    Figure PCTCN2021081132-appb-100042
    Figure PCTCN2021081132-appb-100043
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100044
    和
    Figure PCTCN2021081132-appb-100045
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100046
    表示取
    Figure PCTCN2021081132-appb-100047
    和
    Figure PCTCN2021081132-appb-100048
    中的较大值。
  26. 根据权利要求25所述的方法，其特征在于，所述第一三抽头滤波器包括：
    Figure PCTCN2021081132-appb-100049
    Figure PCTCN2021081132-appb-100050
    Figure PCTCN2021081132-appb-100051
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100052
    和
    Figure PCTCN2021081132-appb-100053
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100054
    表示取
    Figure PCTCN2021081132-appb-100055
    和
    Figure PCTCN2021081132-appb-100056
    中的较大值。
  27. 根据权利要求22所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式确定滤波器，包括：
    当所述亮度分量帧内预测模式所指示的帧内预测方向是水平方向时，所述滤波器设置为第二滤波器。
  28. 根据权利要求27所述的方法，其特征在于，所述第二滤波器包括用于对所述色度分量的参考预测块的左边界像素区域进行滤波的第二两抽头滤波器和用于对所述色度分量的参考预测块的非 左边界像素区域进行滤波的第二三抽头滤波器。
  29. 根据权利要求28所述的方法，其特征在于，所述第二两抽头滤波器包括：
    Figure PCTCN2021081132-appb-100057
    Figure PCTCN2021081132-appb-100058
    Figure PCTCN2021081132-appb-100059
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100060
    和
    Figure PCTCN2021081132-appb-100061
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100062
    表示取
    Figure PCTCN2021081132-appb-100063
    和
    Figure PCTCN2021081132-appb-100064
    中的较大值。
  30. 根据权利要求29所述的方法，其特征在于，所述第二三抽头滤波器包括：
    Figure PCTCN2021081132-appb-100065
    Figure PCTCN2021081132-appb-100066
    Figure PCTCN2021081132-appb-100067
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100068
    和
    Figure PCTCN2021081132-appb-100069
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100070
    表示取
    Figure PCTCN2021081132-appb-100071
    和
    Figure PCTCN2021081132-appb-100072
    中的较大值。
  31. 根据权利要求22所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式为所述当前解码块选择滤波器，包括：
    当所述亮度分量帧内预测模式所指示的帧内预测方向是对角线方向时，所述滤波器设置为第三滤波器。
  32. 根据权利要求31所述的方法，其特征在于，所述第三滤波器包括用于对所述色度分量参考预测块的左边界像素区域和上边界像素区域进行滤波的第三两抽头滤波器和用于对所述色度分量参考预测块的除左边界像素区域和上边界像素区域之外的像素区域进行滤波的第三三抽头滤波器。
  33. 根据权利要求32所述的方法，其特征在于，所述第三两抽头滤波器包括：
    P C＝(P′ C(2x,2y)+P′ C(2x+1,2y+1)+1)>>1；
    其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
  34. 根据权利要求33所述的方法，其特征在于，所述第三三抽头滤波器包括：
    P C＝(3×P′ C(2x,2y)+3×P′ C(2x+1,2y+1)+2×P′ C(2x-1,2y-1)+4)>>3；
    其中，x，y为所述当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，P C为所述当前像素的色度分量的预测样本。
  35. 根据权利要求21-34任一项所述的方法，其特征在于，所述根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块，包括：
    根据所述色度分量帧内预测模式，确定所述当前解码块的亮度分量的重构块；
    根据所述当前解码块的亮度分量的重构块，确定所述当前解码块的色度分量的参考预测块。
  36. 根据权利要求35所述的方法，其特征在于，所述根据所述当前解码块的亮度分量的重构块，确定所述当前解码块的色度分量的参考预测块，包括：
    确定利用所述当前解码块的亮度分量的重构块进行跨分量预测的线性模型；
    根据所述线性模型计算所述亮度分量的重构块，得到所述当前解码块的色度分量的参考预测块。
  37. 根据权利要求36所述的方法，其特征在于，所述确定利用所述当前解码块的亮度分量的重构块进行跨分量预测的线性模型，包括：
    确定用于计算所述线性模型的参考像素，所述参考像素包括所述当前解码块的至少一个相邻像素；
    根据所述参考像素计算所述线性模型。
  38. 根据权利要求37所述的方法，其特征在于，所述确定用于计算所述线性模型的参考像素，包括：
    根据所述当前解码块的相邻像素的重构样本的可用信息和所述色度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
  39. 根据权利要求37所述的方法，其特征在于，所述确定用于计算所述线性模型的参考像素，包括：
    根据所述当前解码块的相邻解码块的码率失真代价最优的亮度分量帧内预测模式，确定用于计算所述线性模型的参考像素。
  40. 根据权利要求25所述的方法，其特征在于，所述第一三抽头滤波器包括：
    Figure PCTCN2021081132-appb-100073
    Figure PCTCN2021081132-appb-100074
    Figure PCTCN2021081132-appb-100075
    其中，x，y为当前像素的坐标，P′ C为所述当前像素的亮度分量的预测样本，
    Figure PCTCN2021081132-appb-100076
    和
    Figure PCTCN2021081132-appb-100077
    为所述当前像素的色度分量的参考预测样本，P C为所述当前像素的色度分量的预测样本，
    Figure PCTCN2021081132-appb-100078
    表示取
    Figure PCTCN2021081132-appb-100079
    和
    Figure PCTCN2021081132-appb-100080
    中的较大值。
  41. 一种图像编码装置，其特征在于，包括：
    划分单元，用于划分图像，确定当前编码块的亮度分量帧内预测模式和色度分量帧内预测模式；
    确定单元，用于当所述色度分量帧内预测模式指示使用所述当前编码块的亮度分量推导所述当前编码块的色度分量时，根据所述亮度分量帧内预测模式，确定所述当前编码块的色度分量的参考预测块；
    滤波单元，用于对所述当前编码块的色度分量的参考预测块进行滤波，得到所述当前编码块的色度分量的预测块。
  42. 一种图像解码装置，其特征在于，包括：
    解析单元，用于解析码流，确定当前解码块的亮度分量帧内预测模式和色度分量帧内预测模式；
    确定单元，用于当所述色度分量帧内预测模式指示使用所述当前解码块的亮度分量的重构块推导所述当前解码块的色度分量的预测值时，根据所述亮度分量帧内预测模式，确定所述当前解码块的色度分量的参考预测块；
    滤波单元，用于对所述当前解码块的色度分量的参考预测块进行滤波，得到所述当前解码块的色度分量的预测块。
  43. 一种编码器，包括非易失性存储介质以及中央处理器，其特征在于，所述非易失性存储介质存储有可执行程序，所述中央处理器与所述非易失性存储介质连接，当所述中央处理器执行所述可执行程序时，所述编码器执行如权利要求1-20中任意一项所述的双向帧间预测方法。
  44. 一种解码器，包括非易失性存储介质以及中央处理器，其特征在于，所述非易失性存储介质存储有可执行程序，所述中央处理器与所述非易失性存储介质连接，当所述中央处理器执行所述可执行程序时，所述解码器执行如权利要求21-40中任意一项所述的双向帧间预测方法。
  45. 一种终端，其特征在于，所述终端包括：一个或多个处理器、存储器和通信接口；所述存储器、所述通信接口与所述一个或多个处理器连接；所述终端通过所述通信接口与其他设备通信，所述存储器用于存储计算机程序代码，所述计算机程序代码包括指令，
    当所述一个或多个处理器执行所述指令时，所述终端执行如权利要求1-40中任意一项所述的方法。
  46. 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终端上运行时，使得所述终端执行如权利要求1-40中任意一项所述的方法。
  47. 一种计算机可读存储介质，包括指令，其特征在于，当所述指令在终端上运行时，使得所述终端执行如权利要求1-40中任意一项所述的方法。
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