Method for encoding/decoding image and device thereof
A method for image decoding, according to the present invention, includes the following steps: receiving image information including a plurality of filter coefficients; generating a restored block for a current block on the basis of the image information; and applying an adaptive loop filter to the restored block on the basis of the plurality of filter coefficients. According to the present invention, image encoding efficiency may be improved, and complexity may be reduced.
1. An image decoding method by a decoding apparatus, comprising:
obtaining prediction information, residual information, and offset information for a sample adaptive offset (SAO) process from a bitstream;
deriving prediction samples based on the prediction information;
deriving residual samples based on the residual information;
generating a reconstructed picture based on the prediction samples and the residual samples; and
applying an in-loop filtering process to the reconstructed picture,
wherein applying the in-loop filtering process includes applying a deblocking filtering process to the reconstructed picture, and applying the SAO process to a sample in the reconstructed picture to which the deblocking filtering process is completed,
wherein the offset information includes offset type information representing that a band offset type is applied to the sample,
wherein the offset information includes information on n offset values, and
wherein the offset information includes explicit band information indicating one of 32 bands as a starting band of a band group consisting of n bands, and an offset value related to a band among the n bands is applied to the sample, wherein n is an integer.
2. The image decoding method of claim 1 , wherein the offset is applied to the sample based on the offset information which is transmitted for a largest coding unit to which the sample belongs.
3. The image decoding method of claim 1 , wherein the band is determined as a predetermined sample value range to which the sample belongs.
4. The image decoding method of claim 1 , wherein the n bands are specified as the starting band and following bands according to sample value order,
wherein the offset value is determined based on the band to which the sample belongs.
5. The image decoding method of claim 1 , wherein the n is predetermined as a constant value.
6. The image decoding method of claim 1 , wherein the band information further indicates a last band among the n bands.
7. An image encoding method by an encoding apparatus, comprising:
deriving prediction samples in a current picture based on inter prediction or intra prediction;
deriving residual samples in the current picture based on the prediction sample;
generating a reconstructed picture of the current picture based on the prediction samples and the residual samples;
applying an in-loop filtering process to the reconstructed picture, wherein applying the in-loop filtering process includes applying a deblocking filtering process to the reconstructed picture, and applying a sample adaptive offset (SAO) process to a sample in the reconstructed picture to which the deblocking filtering process is completed; and
encoding prediction information on the prediction samples, residual information on the residual samples, and offset information for the SAO process,
wherein the offset information includes offset type information representing that a band offset type is applied to the sample,
wherein the offset information includes information on n offset values, and
wherein the offset information includes explicit band information indicating one of 32 bands as a starting band of a band group consisting of n bands, and an offset value related to a band among the n bands is applied to the sample, wherein n is an integer.
8. The image encoding method of claim 7 , wherein the offset is applied to the sample based on the offset information which is transmitted for a largest coding unit to which the sample belongs.
9. The image encoding method of claim 7 , wherein the band is determined as a predetermined sample value range to which the sample belongs.
10. The image encoding method of claim 7 , wherein the n bands are specified as the starting band and following bands according to sample value order,
wherein the offset value is determined based on the band to which the sample belongs.
11. The image encoding method of claim 7 , wherein the n is predetermined as a constant value.
12. The image encoding method of claim 7 , wherein the band information further indicates a last band among the n bands.
13. A transmission method of data for an image, the transmission method comprising:
obtaining a bitstream generated based on deriving prediction samples in a current picture based on inter prediction or intra prediction, deriving residual samples in the current picture based on the prediction samples, generating a reconstructed picture of the current picture based on the prediction samples and the residual samples, applying an in-loop filtering process to the reconstructed picture, wherein applying the in-loop filtering process includes applying a deblocking filtering process to the reconstructed picture, and applying a sample adaptive offset (SAO) process to a sample in the reconstructed picture to which the deblocking filtering process is completed, and generating the bitstream by encoding prediction information on the prediction samples, residual information on the residual samples, and offset information for the SAO process; and
transmitting the data comprising the bitstream,
wherein the offset information includes offset type information representing that a band offset type is applied to the sample,
wherein the offset information includes information on n offset values, and
wherein the offset information includes explicit band information indicating one of 32 bands as a starting band of a band group consisting of n bands, and an offset value related to a band among the n bands is applied to the sample, wherein n is an integer.
14. The transmission method of claim 13 , wherein the band is determined as a predetermined sample value range to which the sample belongs.
15. The transmission method of claim 13 , wherein the n bands are specified as the starting band and following bands according to sample value order,
wherein the offset value is determined based on the band to which the sample belongs.
16. The transmission method of claim 13 , wherein the n is predetermined as a constant value.
17. The transmission method of claim 13 , wherein the band information further indicates a last band among the n bands.