Method and apparatus for encoding images using template matching and method and apparatus for decoding images

1. An image encoding method, comprising:

determining a template of an encoding target block;

determining a matching search target image which performs matching search with the template by using at least one of encoding information of an image to which the encoding target block belongs, encoding information of a neighboring block, and user definition information;

determining an optimal prediction block by using the matching search target image and the template; and

generating a residual block by using the optimal prediction block and the encoding target block,

wherein in the determining of the optimal prediction block,

the optimal prediction block is determined by using similarity between the template and a prediction block,

the prediction block has the same geometrical shape as the encoding target block within the matching search target image, and

the similarity is determined by using at least one of distortion between pixels positioned at the template and the prediction block border, difference values between pixels positioned at the template and the prediction block border, variance of difference values between pixels positioned at the template and the prediction block border and correlation values between pixels positioned at the template and the prediction block border.

2. The image encoding method of claim 1 , wherein in the determining of the matching search target image, one or more reference images corresponding to an image type of the image to which the encoding target block belongs among restored reference images are determined as the matching search target image.

3. The image encoding method of claim 1 , wherein in the determining of the matching search target image, one or more reference images corresponding to a reference type of the neighboring block among the restored reference images are determined as the matching search target image.

4. The image encoding method of claim 1 , wherein in the determining of the optimal prediction block,

the optimal prediction block is determined by using distortion between the template and a matching target region and the similarity between the template and the prediction block,

the matching target region has the same geometrical shape as the template within the matching search target image.

5. The image encoding method of claim 4 , wherein the determining of the optimal prediction block includes:

calculating the respective distortions between the template and matching target regions included in a plurality of matching search target images;

selecting a plurality of prediction blocks in the order in which the distortion is smaller;

judging the respective similarities between the selected plurality of prediction blocks and the template; and

determining as the optimal prediction block a prediction block having the highest similarity from the selected plurality of prediction blocks.

6. The image encoding method of claim 4 , wherein the determining of the optimal prediction block includes:

calculating the respective similarities between the template and prediction blocks included in a plurality of matching search target images;

selecting a plurality of prediction blocks in the order in which the similarity is higher;

calculating the respective distortions between matching target regions corresponding to the selected plurality of prediction blocks and the template; and

determining a prediction block in which the distortion is the minimum as the optimal prediction block.

7. The image encoding method of claim 1 , wherein in the determining of the template,

the template is determined by using at least one of a pixel set constituting a restored neighboring block and a prediction pixel set for the encoding target block, and

the restored neighboring block is an already restored block among blocks adjacent to the encoding target block.

8. The image encoding method of claim 1 , wherein in the generating of the residual block, the residual block is generated based on the optimal prediction block, offset, and the encoding target block.

9. The image encoding method of claim 1 , wherein the generating of the residual block includes:

filtering the optimal prediction block; and

generating the residual block by using the filtered optimal prediction block and the encoding target block.

10. The image encoding method of claim 1 , wherein in the determining of the optimal prediction block, the optimal prediction block is determined by using average values of the distortions between the template and the matching target regions and the similarities between the template and the prediction blocks.

11. An image encoding apparatus, comprising:

a matching search target image determining unit determining a matching search target image by using at least one of encoding information of an image to which an encoding target block belongs, encoding information of a neighboring block, and user definition information among restored reference images;

an optimal prediction block determining unit determining an optimal prediction block by using the matching search target image and a template of the encoding target block; and

a residual block generating unit generating a residual block by using the optimal prediction block and the encoding target block,

wherein the optimal prediction block determining unit determines the optimal prediction block by using similarity between the template and a prediction block,

the prediction block has the same geometrical shape as the encoding target block within the matching search target image, and

the similarity is determined by using at least one of distortion between pixels positioned at the template and the prediction block border, difference values between pixels positioned at the template and the prediction block border, variance of difference values between pixels positioned at the template and the prediction block border and correlation values between pixels positioned at the template and the prediction block border.

12. The image encoding apparatus of claim 11 , wherein the matching search target image determining unit determines as the matching search target image one or more reference images among the restored reference images based on at least one of an image type of an image to which the encoding target block belongs, a reference type of the neighboring block, and user definition information.

13. The image encoding apparatus of claim 11 , wherein the optimal prediction block determining unit determines the optimal prediction block by using distortion between the template and a matching target region and the similarity between the template and the prediction block.

14. An image decoding method, comprising:

determining a template of a decoding target block;

determining a matching search target image which performs matching search with the template by using at least one of decoding information of an image to which the decoding target block belongs, decoding information of a neighboring block, and matching search target image information;

determining an optimal prediction block by using the matching search target image and the template; and

generating restored blocks based on the optimal prediction block and restored residual blocks,

wherein in the determining of the optimal prediction block,

the optimal prediction block is determined by using similarity between the template and a prediction block,

the prediction block has the same geometrical shape as the decoding target block within the matching search target image, and

the similarity is determined by using at least one of distortion between pixels positioned at the template and the prediction block border, difference values between pixels positioned at the template and the prediction block border, variance of difference values between pixels positioned at the template and the prediction block border and correlation values between pixels positioned at the template and the prediction block border.

15. The image decoding method of claim 14 , wherein in the determining of the matching search target image,

one or more reference images are determined as the matching search target image based on at least one of an image type of the image to which the encoding target block belongs among restored reference images, a reference type of the neighboring block, and the matching search target image information, and

the matching search target image information is received by using a sequence parameter set (SPS) or a picture parameter set (PPS).

16. The image decoding method of claim 14 , wherein in the determining of the optimal prediction block,

the optimal prediction block is determined by using distortion between the template and a matching target region and the similarity between the template and the prediction block,

the matching target region has the same geometrical shape as the template within the matching search target image.

17. The image decoding method of claim 14 , wherein in the determining of the template,

the template is determined by using at least one of a pixel set constituting a restored neighboring block and a prediction pixel set for the decoding target block, and

the restored neighboring block is an already restored block among blocks adjacent to the decoding target block.

18. The image decoding method of claim 14 , wherein in the generating of the restored blocks, the restored blocks are generated based on the optimal prediction block, offset, and the restored residual blocks.

19. The image decoding method of claim 14 , wherein the generating of the restored blocks includes:

filtering the optimal prediction block; and

generating the restored blocks by using the filtered optimal prediction block and the restored residual blocks.

20. An image decoding apparatus, comprising:

a matching search target image determining unit determining a matching search target image which performs matching search with the template of the decoding target block by using at least one of decoding information of an image to which a decoding target block belongs, decoding information of a neighboring block, and matching search target image information;

an optimal prediction block determining unit determining an optimal prediction block by using the matching search target image and the template; and

a restored block generating unit generating restored blocks based on the optimal prediction block and restored residual blocks,

wherein the optimal prediction block determining unit determines the optimal prediction block by using similarity between the template and a prediction block,

the prediction block has the same geometrical shape as the decoding target block within the matching search target image, and

the similarity is determined by using at least one of distortion between pixels positioned at the template and the prediction block border, difference values between pixels positioned at the template and the prediction block border, variance of difference values between pixels positioned at the template and the prediction block border and correlation values between pixels positioned at the template and the prediction block border.