CN-122029804-A - Image encoding/decoding method, recording medium having bit stream stored thereon, and method for transmitting bit stream

Abstract

An image encoding/decoding method, a bit stream transmission method, and a computer readable recording medium storing a bit stream are provided. An image decoding method according to the present disclosure includes the steps of generating a prediction block of a current block based on a prediction mode of the current block, generating reconstructed samples of the current block based on the prediction block, and performing filtering on the reconstructed samples, wherein the step of generating the prediction block includes the steps of deriving a basic prediction block of the current block, deriving a multi-reference block of the current block, and generating a final prediction block of the current block through weighted summation of the basic prediction block and the multi-reference block, and determining a filter strength for filtering based on prediction information related to the current block, the prediction block, or the multi-reference block.

Inventors

• Pu Laili
• Nan Tingxue
• LIN ZAIXIAN
• An Rongzhao
• JIN SHENGHUAN
• CUI ZHANGYUAN
• Hong Mingwu

Assignees

• LG电子株式会社

Dates

Publication Date

20260512

Application Date

20240913

Priority Date

20230915

Claims (20)

1. 1. An image decoding method performed by a decoding apparatus, the image decoding method comprising: generating a prediction block of a current block based on a prediction mode of the current block; generating reconstructed samples of the current block based on the prediction block, and The filtering of the reconstructed samples is performed, Wherein generating the prediction block comprises: Deriving a normal prediction block of the current block; Deriving a plurality of reference blocks of the current block, and Generating a final prediction block of the current block by a weighted sum of the normal prediction block and the plurality of reference blocks, Wherein a filtering strength for filtering is determined based on prediction information of the current block, the prediction block, or the plurality of reference blocks.
2. 2. The image decoding method of claim 1, wherein the prediction information includes information of a prediction mode of the current block, a generation method for the prediction block, or prediction modes of the plurality of reference blocks.
3. 3. The image decoding method of claim 1, wherein the filtering comprises deblocking filtering, and Wherein the filter strength is set to a first value when a predetermined first condition is met, the first value comprising a value of 2 or 3.
4. 4. The image decoding method of claim 3, wherein the predetermined first condition includes a case where the current block or a neighboring block adjacent to the current block is in an intra mode, the current block or the neighboring block is in a Combined Inter and Intra Prediction (CIIP) mode, or a number of blocks in an intra mode among the plurality of reference blocks is greater than 0.
5. 5. The image decoding method of claim 4, wherein the filter strength is set to the first value when the current block or the neighboring block is in the intra mode.
6. 6. The image decoding method of claim 4, wherein the filter strength is set to the first value when the current block or the neighboring block is in the CIIP mode.
7. 7. The image decoding method of claim 4, wherein the filter strength is set to the first value when the number of blocks in the intra mode among the plurality of reference blocks is greater than 0.
8. 8. The image decoding method of claim 7, wherein the plurality of reference blocks located in the current block or the neighboring block are signaled or inherited plurality of reference blocks.
9. 9. A method of decoding an image performed by a decoding device, the method comprising: generating a prediction block of the current block based on prediction information obtained from the bitstream; Deriving transform coefficients by performing dequantization based on residual information obtained from the bitstream; Deriving a residual block by performing inverse transform of the transform coefficients, and Generate reconstructed samples based on the prediction block and the residual block, Wherein generating the prediction block comprises: Generating a conventional prediction block of the current block; Deriving a plurality of reference blocks of the current block, and Deriving a final prediction block of the current block by a weighted sum of the normal prediction block and the plurality of reference blocks, Wherein it is determined whether a sub-block transform (SBT) is applied to the current block based on prediction modes of the plurality of reference blocks.
10. 10. The image decoding method of claim 9, wherein the SBT is determined to be applied to the current block when the prediction modes of the plurality of reference blocks are not in intra mode.
11. 11. The image decoding method of claim 9, wherein it is determined to apply the SBT to the current block when a predetermined second condition is satisfied, and Wherein the predetermined second condition includes a case where the number of blocks in an intra mode among the plurality of reference blocks is greater than 0.
12. 12. The image decoding method of claim 11, wherein it is determined to apply the SBT to the current block when a number of blocks in the intra mode among the plurality of reference blocks is greater than 0.
13. 13. A method of decoding an image performed by a decoding device, the method comprising: generating a prediction block of the current block based on prediction information obtained from the bitstream; Deriving transform coefficients by performing dequantization based on residual information obtained from the bitstream; Deriving a residual block by performing inverse transform of the transform coefficients, and Generate reconstructed samples based on the prediction block and the residual block, Wherein generating the prediction block comprises: Generating a conventional prediction block of the current block; Deriving a plurality of reference blocks of the current block, and Deriving a final prediction block of the current block by a weighted sum of the normal prediction block and the plurality of reference blocks, Wherein a transform kernel for the inverse transform is determined based on a prediction mode associated with at least one of the normal prediction block and the plurality of reference blocks.
14. 14. The image decoding method of claim 13, wherein when the prediction modes of the plurality of reference blocks are in an intra mode, a representative intra mode is determined by considering directionality of each intra mode, and a secondary transform core of the representative intra mode is determined as a transform core for the inverse transform.
15. 15. The image decoding method of claim 13, wherein when the prediction modes of the plurality of reference blocks are in an intra mode, any one of the intra modes is selected based on directionality of each intra mode, and a secondary transform core of the selected intra mode is determined as a transform core for the inverse transform.
16. 16. The image decoding method of claim 13, wherein when the prediction modes of the plurality of reference blocks are not in an intra mode, an inverse secondary transform is not applied or a core of a plane mode is determined as a transform core for the inverse transform.
17. 17. The image decoding method of claim 13, wherein the regular prediction blocks are derived based on at least one of regular reference blocks, and a secondary transform core of the at least one of regular prediction blocks is determined as a transform core for the inverse transform when a prediction mode of the at least one of regular prediction blocks is in an intra mode.
18. 18. The image decoding method of claim 17, wherein when the prediction mode of at least one of the regular prediction blocks is in an intra mode and the prediction modes of the plurality of reference blocks are in an intra mode, a representative intra mode is determined by considering directionality of each intra mode, and a secondary transform core of the representative intra mode is determined as a transform core for the inverse transform.
19. 19. The image decoding method of claim 13, wherein, when the prediction mode of at least one of the regular prediction blocks is in an intra mode and the prediction modes of the plurality of reference blocks are in an intra mode, a secondary transform core of the regular prediction block is determined as a transform core for the inverse transform based on directionality of each intra mode matching each other.
20. 20. An image encoding method performed by an encoding apparatus, the image encoding method comprising: generating a prediction block of a current block based on a prediction mode of the current block; generating reconstructed samples of the current block based on the prediction block, and The filtering of the reconstructed samples is performed, Wherein generating the prediction block comprises: Deriving a normal prediction block of the current block; Deriving a plurality of reference blocks of the current block, and Generating a final prediction block of the current block by a weighted sum of the normal prediction block and the plurality of reference blocks, Wherein a filtering strength for filtering is determined based on prediction information of the current block, the prediction block, or the plurality of reference blocks.

Description

Image encoding/decoding method, recording medium having bit stream stored thereon, and method for transmitting bit stream Technical Field The present disclosure relates to an image encoding/decoding method, a recording medium having a bitstream stored thereon, and a method of transmitting a bitstream, and more particularly, to an encoding/decoding process related to a multi-reference block. Background Recently, demands for high resolution and high quality images such as HD (high definition) images and UHD (ultra high definition) images have been increasing in various application fields, and thus, efficient image compression techniques are being discussed. There are various techniques such as an inter-prediction technique of predicting pixel values included in a current picture from a picture before or after the current picture using a video compression technique, an intra-prediction technique of predicting pixel values included in the current picture by using pixel information in the current picture, an entropy encoding technique of assigning short symbols to values having a high frequency of occurrence and assigning long symbols to values having a low frequency of occurrence, and the like, and these image compression techniques may be used to efficiently compress image data and transmit or store it. Therefore, an efficient image compression technique is required to efficiently transmit, store, and reproduce information about high resolution and high quality images. Disclosure of Invention [ Technical problem ] The present disclosure is directed to an image encoding method and apparatus having improved encoding/decoding efficiency. In addition to the basic reference blocks derived during the prediction process, the present disclosure also aims to improve the prediction performance when deriving reference blocks. The present disclosure is also directed to improving the efficiency of the encoding/decoding process when multiple reference blocks are present. The present disclosure is also directed to a non-transitory computer readable recording medium for storing a bitstream generated using the image encoding method according to the present disclosure. The present disclosure is also directed to a method of transmitting a bitstream generated using the image encoding method according to the present disclosure. Technical objects to be achieved by the present disclosure are not limited to the above technical objects, and other technical objects not yet described will be clearly understood by those skilled in the art to which the present disclosure pertains from the following description. Technical scheme According to an embodiment of the present disclosure, an image decoding method performed by a decoding apparatus includes generating a prediction block of a current block based on a prediction mode of the current block, generating reconstructed samples of the current block based on the prediction block, and performing filtering of the reconstructed samples, wherein generating the prediction block includes deriving a normal prediction block of the current block, deriving a plurality of reference blocks of the current block, and generating a final prediction block of the current block through a weighted sum of the normal prediction block and the plurality of reference blocks, wherein a filter strength for filtering is determined based on prediction information of the current block, the prediction block, or the plurality of reference blocks. According to an embodiment of the present disclosure, a method of decoding an image performed by a decoding apparatus includes generating a prediction block of a current block based on prediction information obtained from a bitstream, deriving a transform coefficient by performing dequantization based on residual information obtained from the bitstream, deriving a residual block by performing inverse transform of the transform coefficient, and generating a reconstructed sample based on the prediction block and the residual block, wherein generating the prediction block includes generating a normal prediction block of the current block, deriving a plurality of reference blocks of the current block, and deriving a final prediction block of the current block by a weighted sum of the normal prediction block and the plurality of reference blocks, wherein whether to apply a sub-block transform (SBT) to the current block is determined based on a prediction mode of the plurality of reference blocks. According to an embodiment of the present disclosure, a method of decoding an image performed by a decoding apparatus includes generating a prediction block of a current block based on prediction information obtained from a bitstream, deriving a transform coefficient by performing dequantization based on residual information obtained from the bitstream, deriving a residual block by performing inverse transform of the transform coefficient, and generating a reconstructed sample based on the pre