Image information encoding and decoding method
The present invention relates to an image information encoding and decoding method and a device for same. One embodiment of an image information encoding method according to the present invention, as an image information encoding method according to another embodiment of the present invention, includes the steps of: generating a restore block; applying a deblocking filter on the restore block; applying a Sample Adaptive Offset (SAO) on the restore block having the deblocking filter applied thereon; and transmitting information on the SAO application. During the applying of the SAO, the SAO is applied to chroma pixels, and during the transmitting of the information, in addition to information on whether the SAO is applied on the chroma pixels, at least one of area information, division information on the SAO coverage area, SAO type information, and SAO offset information is transmitted.
1. A method for decoding a video by a video decoder, the method comprising:
receiving prediction information and offset information through a bitstream;
generating a prediction sample based on the prediction information;
generating a reconstructed picture based on the prediction sample; and
performing sample adaptive offset (SAO) process on at least one of a luma sample or a chroma sample in the reconstructed picture,
wherein the offset information includes first flag information indicating whether the SAO process is enabled to the luma sample or not, and second flag information indicating whether the SAO process is enabled to the chroma sample or not, and
wherein the offset information includes band information indicating one of 32 bands as a starting band of a band group consisting of n (n is an integer) bands among the 32 bands, the band group is determined based on the starting band, and an offset corresponding to a band among the n bands is applied to the luma sample or the chroma sample.
2. The method of claim 1 , wherein the offset information includes luma type information specifying an offset type for the luma sample, and chroma type information specifying an offset type for the chroma sample.
3. The method of claim 2 , wherein the luma type information and the chroma type information are obtained based on entropy decoding using a context-adaptive arithmetic coding on the bitstream.
4. The method of claim 2 , wherein the offset information includes luma offset information specifying a magnitude of a first offset applied to the luma sample, and chroma offset information specifying a magnitude of a second offset applied to the chroma sample.
5. The method of claim 4 , wherein the luma offset information and the chroma offset information are obtained based on entropy decoding using a context-adaptive arithmetic coding on the bitstream.
6. The method of claim 1 , wherein the luma type information indicates a band offset type for the luma sample, and
wherein the chroma type information indicates a band offset type for the chroma sample.
7. The method of claim 1 , wherein the band is determined as a predetermined sample value range to which the luma sample belongs.
8. The method of claim 1 , wherein the n is predetermined as a constant number.
9. The method of claim 1 , wherein the band information indicating an ending band of the band group, the band group is determined based on both the starting band and the ending band.
10. The method of claim 1 , wherein the 32 bands are sections into which the whole sample value regions are divided with a constant size.
11. The method of claim 1 , wherein the step of obtaining the video information includes
obtaining the first flag information through entropy-decoding on the bitstream using a method other than the method of entropy-decoding the luma type information from the bitstream, and
obtaining the second flag information through entropy-decoding on the bitstream using a method other than the method of entropy-decoding the chroma type information from the bitstream.
12. The method of claim 11 , wherein the first flag information and the second flag information are entropy decoded using an exponential Golomb (Exp-Golomb) method, and
wherein the luma type information and the chroma type information are entropy decoded using a context-adaptive arithmetic coding.