Method for encoding/decoding image and device thereof
A method for image decoding 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.
1. A picture decoding method by a decoding apparatus, comprising:
receiving prediction information for a prediction process and offset information for a sample adaptive offset (SAO) process;
deriving prediction samples based on the prediction information;
generating a reconstructed picture based on the prediction 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 on which the deblocking filtering process is completed,
wherein the offset information includes offset type information indicating a SAO type applied to the sample, and
wherein when the offset type information indicates that a band offset type is applied to the sample, 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 corresponding to a band among the n bands is applied to the sample, wherein n is an integer.
2. The method of claim 1 , wherein when the offset type information indicating the edge offset type is applied to the sample, applying the SAO process comprises calculating the difference between the sample and the neighboring samples based on a direction of an edge specifying locations of the sample and the neighboring samples and determining the category of the sample based on the difference.
3. The 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.
4. The method of claim 1 , wherein the band is determined as a predetermined sample value range to which the sample belongs.
5. The 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 is determined based on the band to which the sample belongs.
6. The method of claim 1 , wherein the n bands are bands for which information indicating offset values is transmitted.
7. The method of claim 1 , wherein the n is predetermined as a constant value.
8. The method of claim 1 , wherein the band information further indicates a last band among the n bands.
9. The method of claim 8 , wherein the available bands are specified as the last band and bands followed by the last band according to sample value order,
wherein the offset is determined based on the band which the sample corresponds to.
10. The method of claim 1 , wherein the offset type information is obtained by context-adaptive arithmetic coding.
11. A picture decoding apparatus, comprising:
an entropy decoding module for receiving prediction information for a prediction process and offset information for a sample adaptive offset (SAO) process;
a prediction module for deriving prediction samples based on the prediction information;
an adder for generating a reconstructed picture based on the prediction samples; and
a filter module for applying an in-loop filtering process to the reconstructed picture,
wherein for the in-loop filtering process, the filter applies a deblocking filtering process to the reconstructed picture, and applies the SAO process to a sample in the reconstructed picture on which the deblocking filtering process is completed,
wherein the offset information includes offset type information indicating a SAO type applied to the sample, and
wherein when the offset type information indicates that a band offset type is applied to the sample, 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 corresponding to a band among the n bands is applied to the sample, wherein n is an integer.
12. The apparatus of claim 11 , wherein when the offset type information indicating the edge offset type is applied to the sample, for the SAO process the filter calculates the difference between the sample and the neighboring samples based on a direction of an edge specifying locations of the sample and the neighboring samples and determines the category of the sample based on the difference.
13. The apparatus of claim 11 , 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.
14. The apparatus of claim 11 , wherein the band is determined as a predetermined sample value range to which the sample belongs.
15. The apparatus of claim 11 , wherein the n bands are specified as the starting band and following bands according to sample value order,
wherein the offset is determined based on the band to which the sample belongs.
16. The apparatus of claim 11 , wherein the n bands are bands for which information indicating offset values is transmitted.
17. The apparatus of claim 11 , wherein the n is predetermined as a constant value.
18. The apparatus of claim 11 , wherein the band information further indicates a last band among the n bands.
19. The apparatus of claim 18 , wherein the available bands are specified as the last band and bands followed by the last band according to sample value order,
wherein the offset is determined based on the band which the sample corresponds to.
20. The apparatus of claim 11 , wherein the offset type information is obtained by context-adaptive arithmetic coding.