Image encoder and decoder using unidirectional prediction
The present invention relates to an image encoding and decoding technique, and more particularly, to an image encoder and decoder using unidirectional prediction. The image encoder includes a dividing unit to divide a macro block into a plurality of sub-blocks, a unidirectional application determining unit to determine whether an identical prediction mode is applied to each of the plurality of sub-blocks, and a prediction mode determining unit to determine a prediction mode with respect to each of the plurality of sub-blocks based on a determined result of the unidirectional application determining unit.
1. An image decoding method to decode a plurality of sub-blocks in a block, comprising;
determining an intra prediction mode;
determining a decoding order among the plurality of the sub-blocks in the block based on the intra prediction mode; and
decoding the plurality of the sub-blocks based on the decoding order.
2. The image decoding method of claim 1 ,
wherein the decoding order is one of a plurality of decoding orders for intra prediction selected based on the intra prediction mode, and
the intra prediction mode is one of a plurality of intra prediction modes.
3. The image decoding method of claim 2 ,
wherein the plurality of intra prediction modes includes an intra prediction of diagonal down-left direction, an intra prediction of vertical-left direction and an intra prediction of horizontal-up direction.
4. The image decoding method of claim 1 ,
wherein the plurality of the sub-blocks include top-left sub-block, top-right sub-block, bottom-left sub-block, and bottom-right sub-block.
5. The image decoding method of claim 4 ,
wherein the plurality of the sub-blocks is decoded in an order of the top-right sub-block, the top-left sub-block, the bottom-right sub-block and the bottom-left sub-block.
6. The image decoding method of claim 4 ,
wherein the plurality of the sub-blocks is decoded in an order of the top-right sub-block, the top-left sub-block, the bottom-right sub-block and the bottom-left sub-block when the intra prediction mode is a predetermined intra prediction mode.
7. The image decoding method of claim 4 ,
wherein the plurality of the sub-blocks is decoded in an order of the top-right sub-block, the top-left sub-block, the bottom-right sub-block and the bottom-left sub-block when a direction of the intra prediction mode corresponds to a diagonal down-left direction.
8. The image decoding method of claim 4 ,
wherein a decoded pixel of the top-right sub-block is used for a decoding of the top-left sub-block, and
a decoded pixel of the bottom-right sub-block is used for a decoding of the bottom-left sub-block.
9. The image decoding method of claim 4 ,
wherein a decoding of the top-right sub-block is performed before a decoding of the top-left sub-block, and
a decoding of the bottom-right sub-block is performed before a decoding of the bottom-left sub-block.
10. An image encoding method to encode a plurality of sub-blocks in a block, comprising;
determining an intra prediction mode;
generating encoded information for the block based on the intra prediction mode, wherein
a decoding of the plurality of the sub-blocks in the block is performed using the encoded information, and
a decoding order between the plurality of the sub-blocks is determined based on the intra prediction mode.
11. The image encoding method of claim 10 ,
wherein the decoding order is one of a plurality of decoding orders for intra prediction selected based on the intra prediction mode, and
the intra prediction mode is one of a plurality of intra prediction modes.
12. The image encoding method of claim 11 ,
wherein the plurality of intra prediction modes includes an intra prediction of diagonal down-left direction, an intra prediction of vertical-left direction and an intra prediction of horizontal-up direction.
13. The image encoding method of claim 10 ,
wherein the plurality of the sub-blocks include top-left sub-block, top-right sub-block, bottom-left sub-block, and bottom-right sub-block.
14. The image encoding method of claim 13 ,
wherein the plurality of the sub-blocks is decoded in an order of the top-right sub-block, the top-left sub-block, the bottom-right sub-block and the bottom-left sub-block.
15. The image encoding method of claim 13 ,
wherein a decoded pixel of the top-right sub-block is used for a decoding of the top-left sub-block, and
a decoded pixel of the bottom-right sub-block is used for a decoding of the bottom-left sub-block.
16. The image encoding method of claim 13 ,
wherein a decoding of the top-right sub-block is performed before a decoding of the top-left sub-block, and
a decoding of the bottom-right sub-block is performed before a decoding of the bottom-left sub-block.
17. A non-transitory computer-readable medium storing a bitstream, the bitstream comprising:
encoded information for a block;
intra prediction mode information indicating an intra prediction mode for the block;
wherein a decoding of a plurality of sub-blocks in the block is performed using the encoded information, and
a decoding order between the plurality of the sub-blocks is determined based on the intra prediction mode.
18. The non-transitory computer-readable medium of claim 17 ,
wherein the decoding order is one of a plurality of decoding orders for intra prediction selected based on the intra prediction mode, and
the intra prediction mode is one of a plurality of intra prediction modes.
19. The non-transitory computer-readable medium of claim 18 ,
wherein the plurality of intra prediction modes includes an intra prediction of diagonal down-left direction, an intra prediction of vertical-left direction and an intra prediction of horizontal-up direction.
20. The non-transitory computer-readable medium of claim 17 ,
wherein the plurality of the sub-blocks include top-left sub-block, top-right sub-block, bottom-left sub-block, and bottom-right sub-block,
a decoding of the top-right sub-block is performed before a decoding of the top-left sub-block, and
a decoding of the bottom-right sub-block is performed before a decoding of the bottom-left sub-block.