Image encoding/decoding method and device
The present invention relates to an image encoding/decoding method and apparatus. An image encoding method according to the present invention may comprise generating a transform block by performing at least one of transform and quantization; grouping at least one coefficient included in the transform block into at least one coefficient group (CG); scanning at least one coefficient included in the coefficient group; and encoding the at least one coefficient.
1. An image encoding method, comprising:
performing prediction for a current block using a prediction mode for the current block;
determining a transform kernel of the current block;
generating at least one coefficient of the current block by performing a transform on residual samples of the current block, based on the transform kernel; and
encoding transform kernel information indicating the transform kernel of the current block and the at least one coefficient of the current block,
wherein the transform comprises a primary transform and a secondary transform,
wherein the at least one coefficient is generated by performing the secondary transform on a result of the primary transform on the residual samples using the transform kernel,
wherein the transform kernel information is an index indicating one of predefined transform kernel sets as the transform kernel of the current block,
wherein each of the predefined transform kernel sets comprises a predefined horizontal transform kernel and a predefined vertical transform kernel,
wherein the transform kernel of the current block comprises a horizontal transform kernel and a vertical transform kernel, and
wherein the horizontal transform kernel and the vertical transform kernel of the transform kernel of the current block are determined based on a partition form specifying how many sub-blocks the current block is partitioned into, a size of the current block, whether inter prediction is used for the prediction for the current block or not and whether intra prediction is used for the prediction for the current block or not.
2. The image encoding method of claim 1 , wherein the transform kernel information is encoded for each of coding units.
3. The image encoding method of claim 1 , wherein the transform kernel information is selectively encoded based on whether a size of the current block is less than or equal to a predefined size.
4. The image encoding method of claim 1 , wherein the transform kernel information is selectively encoded based on whether a non-zero transform coefficient exists in the current block.
5. The image encoding method of claim 1 , wherein whether a transform skip mode is performed on the current block is determined, and
the transform kernel information is encoded in a case that it is determined that the transform skip kernel is not performed on the current block.
6. The image encoding method of claim 1 , wherein the horizontal transform kernel and the vertical transform kernel are determined independently.
7. An image decoding method, comprising:
decoding transform kernel information for a current block and at least one coefficient of the current block from a bitstream;
determining a transform kernel of the current block based on the transform kernel information; and
performing a transform on the at least one coefficient of the current block based on the determined transform kernel to generate residual samples,
wherein prediction for the current block using a prediction mode for the current block is performed,
wherein the transform comprises a primary transform and a secondary transform,
wherein the residual samples are generated by performing the primary transform using the transform kernel on a result of the secondary transform on the at least one coefficient,
wherein the transform kernel information is an index indicating one of predefined transform kernel sets as the transform kernel of the current block,
wherein each of the predefined transform kernel sets comprises a predefined horizontal transform kernel and a predefined vertical transform kernel,
wherein the transform kernel of the current block comprises a horizontal transform kernel and a vertical transform kernel, and
wherein the horizontal transform kernel and the vertical transform kernel of the transform kernel of the current block are determined based on a partition form specifying how many sub-blocks the current block is partitioned into, a size of the current block, whether inter prediction is used for the prediction for the current block or not and whether intra prediction is used for the prediction for the current block or not.
8. The image decoding method of claim 7 , wherein the transform kernel information is decoded for each of coding units.
9. The image decoding method of claim 7 , wherein the transform kernel information is selectively decoded based on whether a size of the current block is less than or equal to a predefined size.
10. The image decoding method of claim 7 , wherein the transform kernel information is selectively decoded based on whether a non-zero transform coefficient exists in the current block.
11. The image decoding method of claim 7 , wherein whether a transform skip mode is performed on the current block is determined, and
the transform kernel information is decoded in a case that it is determined that the transform skip kernel is not performed on the current block.
12. The image decoding method of claim 7 , wherein the horizontal transform kernel and the vertical transform kernel are determined independently.
13. A non-transitory computer-recordable medium for storing a bitstream generated by an image encoding method,
wherein the image encoding method includes:
performing prediction for a current block using a prediction mode for the current block;
determining a transform kernel of the current block;
generating at least one coefficient of the current block by performing a transform on residual samples of the current block, based on the transform kernel; and
encoding transform kernel information indicating the transform kernel of the current block and the at least one coefficient of the current block,
wherein the transform comprises a primary transform and a secondary transform,
wherein the at least one coefficient is generated by performing the secondary transform on a result of the primary transform on the residual samples using the transform kernel,
wherein the transform kernel information is an index indicating one of predefined transform kernel sets as the transform kernel of the current block,
wherein each of the predefined transform kernel sets comprises a predefined horizontal transform kernel and a predefined vertical transform kernel,
wherein the transform kernel of the current block comprises a horizontal transform kernel and a vertical transform kernel, and
wherein the horizontal transform kernel and the vertical transform kernel of the transform kernel of the current block are determined based on a partition form specifying how many sub-blocks the current block is partitioned into, a size of the current block, whether inter prediction is used for the prediction for the current block or not and whether intra prediction is used for the prediction for the current block or not.