Method and apparatus for image encoding/decoding

1. A method of decoding an image, comprising:

generating a prediction block for a current block;

receiving information of a first block size, wherein the information of the first block size is determined by an encoder, and wherein whether a skip of a transform process is applicable is determined based on a comparison of the information of the first block size with a current block size;

decoding information indicating whether the skip of the transform process is applied, in response to the comparison of the information of the first block size with the current block size representing that the skip of the transform process is applicable;

determining whether to perform an inverse transform on the current block based on the decoded information indicating whether the skip of the transform process is applied;

performing the inverse transform on the current block to generate a residual block for the current block;

reconstructing the current block based on the prediction block and the residual block; and

applying filtering on the reconstructed current block,

wherein the prediction block is generated by performing intra prediction, and

wherein the filtering comprises either one or both of deblocking filtering and a-sample adaptive offset (SAO) filtering.

2. The method of claim 1 , wherein in response to the decoded information indicating that the transform process is not performed, the inverse transform on the current block is skipped.

3. The method of claim 1 , wherein in response to the decoded information indicating that the transform process is performed, the inverse transform on the current block is performed.

4. The method of claim 1 , wherein in response to a value of transform_skip_flag being 1, the transform process is not performed and is skipped on the current block, and in response to the value of transform_skip_flag being 0, the transform process is performed on the current block.

5. The method of claim 4 , wherein the information indicating whether the skip of the transform process is applied comprises a flag indicating whether to perform the inverse transform on the current block based on the information of the first block size.

6. The method of claim 1 , further comprising performing an inverse transform on the current block according to the current block size, in response to the current block size satisfying a condition in which the skip of the transform process is not applied.

7. The method of claim 6 , wherein the skip of the transform process is applied when the current block size is larger than 4×4 pixels.

8. An apparatus to decode an image, comprising:

at least one processor configured to

generate a prediction block for a current block,

decode information of a first block size and information indicating whether a skip of a transform process is applied, wherein the information of the first block size is determined by an encoder, and wherein whether the skip of the transform process is applicable is determined based on a comparison of the information of the first block size with a current block size,

determine whether to perform an inverse transform on the current block based on the decoded information indicating whether the skip of the transform process is applied,

perform the inverse transform on the current block to generate a residual block for the current block,

reconstruct the current block based on the prediction block and the residual block, and

apply filtering on the reconstructed current block,

wherein the prediction block is generated by performing intra prediction, and

wherein the filtering comprises either one or both of deblocking filtering and sample adaptive offset (SAO) filtering.

9. The apparatus of claim 8 , wherein the skip of the transform process is applied when the current block size is larger than 4×4 pixels.

10. A method of encoding an image, comprising:

generating a prediction block for a current block;

generating a residual block for the current block based on the prediction block;

encoding the residual block;

decoding the encoded residual block;

reconstructing the current block based on the prediction block and the decoded residual block; and

applying filtering on the reconstructed current block,

wherein the prediction block is generated by performing intra prediction,

wherein the filtering comprises either one or both of deblocking filtering and sample adaptive offset (SAO) filtering, and

wherein the encoding of the residual block comprises

determining information of a first block size, wherein whether a skip of a transform process is applicable is determined based on the information of the first block size compared with a current block size;

determining whether to apply the skip of the transform process on the current block based on a comparison of the information of the first block size with a current block size; and

performing a transform on the current block to encode the residual block.

11. The method of claim 10 , further comprising encoding the information indicating whether the skip of the transform process is applied to the current block.

12. The method of claim 10 , wherein in response to a value of transform_skip_flag being 1, the transform process is not performed and is skipped on the current block, and in response to the value of transform_skip_flag being 0, the transform process is performed on the current block.

13. The method of claim 11 , wherein in response to a determination that the skip of the transform process is applied to the current block, the information indicating whether the skip of the transform process is applied to the current block indicates that the transform on the current block is skipped.

14. The method of claim 11 , wherein in response to a determination that that the skip of the transform process is not applied to the current block, the information indicating whether the skip of the transform process is applied to the current block indicates that the transform on the current block is performed.

15. The method of claim 13 , further comprising performing the transform on the current block according to the current block size, in response to the current block size satisfying a condition in which the skip of the transform process is not applied.

16. The method of claim 12 , wherein the information indicating whether the skip of the transform process is applied comprises a flag indicating whether to perform the transform on the current block based on the information of the first block size.

17. The method of claim 16 , wherein the skip of the transform process is applied when the current block size is larger than 4×4 pixels.

18. An apparatus to encode an image, comprising:

at least one processor, configured to

generate a prediction block for a current block,

generate a residual block for the current block based on the prediction block,

encode the residual block,

decode the encoded residual block,

reconstruct the current block based on the prediction block and the decoded residual block, and

apply filtering on the reconstructed current block,

wherein the prediction block is generated by performing intra prediction,

wherein the filtering comprises either one or both of deblocking filtering and sample adaptive offset (SAO) filtering, and

wherein the encoding of the residual block comprises

performing a transform on the current block based on information indicating whether a skip of a transform process is applied, and

encoding information of a first block size and the information indicating whether the skip of the transform process is applied, wherein whether the skip of the transform process is applicable is determined based on a comparison of the information of the first block size with a current block size.

19. The apparatus of claim 18 , wherein the skip of the transform process is applied when the current block size is larger than 4×4 pixels.