Video encoding and decoding method
Disclosed are a method and apparatus for improving the accuracy of intra-prediction in order to improve encoding and decoding efficiency. The video decoding method may improve the prediction efficiency for the current pixel to be predicted by referring to the degree of variation in surrounding pixels, to thereby effectively decode the bit stream with improved encoding efficiency. In addition, an additional prediction candidate is used to achieve improved accuracy of intra-prediction, and the thus-improved accuracy of intra-prediction may reduce residual components and improve encoding efficiency. Further, an improved planar mode is utilized to achieve improved intra-prediction.
1. A video decoding method comprising:
receiving a bit stream generated by calculating a first difference value indicating a difference between a current pixel and a neighbor pixel adjacent to the current pixel in a reverse direction of intra-prediction direction, calculating a prediction value of the first difference value, and performing encoding a second difference value indicating a difference between the first difference value and the prediction value;
decoding the received bit stream; and
generating a reconstructed image based on the reconstructed second difference value and intra-prediction information.
2. The video decoding method of claim 1 ,
wherein the prediction value is calculated based on a difference value between two pixels including a first pixel and a second pixel, the first pixel adjacent to the current pixel and belongs to a neighbor line adjacent to a current line which the current pixel belongs to among plural lines formed according to the intra-prediction direction, the second pixel adjacent to the neighbor pixel and belongs to the neighbor line.
3. The video decoding method of claim 1 ,
wherein the prediction value is calculated by multiplying a weight based on pixel continuity to the difference value between two pixels.
4. A video decoding method comprising:
decoding a received bit stream to generate reconstructed information including a residual value for a current pixel and intra-prediction information;
determining a first prediction value of the current pixel using reference pixels included in a block adjacent to a block to which the current pixel belongs;
determining a second prediction value of the current pixel using neighbor pixels adjacent to the current pixel; and
generating a reconstructed image by adding the residual value of the current pixel to a prediction value selected between the first prediction value and the second prediction value.
5. The video decoding method of claim 4 , wherein the second prediction value is based on a pixel value of the neighbor pixel positioned at a left side, an upper left side, an upper side, or an upper right side of the current block.
6. The video decoding method of claim 4 , wherein the intra-prediction information includes the positions and a number of neighbor pixels adjacent to the current pixel.
7. A video decoding method comprising:
decoding received bit stream to generate reconstruction information including a residual value for a current pixel and intra-prediction information;
generating a first prediction value using a first reference pixel and a pixel T at an upper right corner of a current block including the current pixel based on the intra-prediction information;
generating a second prediction value using a second reference pixel and a pixel L at a lower left corner of the current block including the current pixel based on the intra-prediction information; and
generating a final prediction value for the current pixel using the first prediction value and the second prediction value.
8. The video decoding method of claim 7 ,
wherein the pixel T at the upper right corner of the current block is any one of a pixel TR at an upper right corner of the current pixel, a pixel selected from among pixels positioned in the same horizontal line as the pixel TR at the upper right corner of the current pixel, and a pixel generated by filtering the pixels positioned in the same horizontal line as the pixel TR at the upper right corner of the current pixel, and
wherein the pixel L at the lower left corner of the current block is any one of a pixel LB at a lower left corner of the current pixel, a pixel selected from among pixels positioned in the same vertical line as the pixel LB at the lower left corner of the current pixel, and a pixel generated by filtering the pixels positioned in the same vertical line as the pixel LB at the lower left corner of the current pixel.
9. The video decoding method of claim 7 ,
wherein the first reference pixel is a pixel positioned in the same horizontal line as the current pixel and adjacent to the current block, and
wherein the second reference pixel is a pixel positioned in the same vertical line as the current pixel and adjacent to the current block.
10. The video decoding method of claim 7 , wherein the current block is partitioned into at least two regions, and intra-prediction is sequentially performed for each partitioned region.
11. The video decoding method of claim 7 ,
wherein the generating of the first prediction value includes generating the first prediction value by applying weights to the pixel TR at the upper right corner of the current block and the pixel positioned in the same horizontal line as the current pixel and adjacent to the current block, and
wherein the generating of the second prediction value includes the second prediction value by applying weights to the pixel LB at the lower left corner of the current block and the pixel positioned in the same vertical line as the current pixel and adjacent to the current block.
12. The video decoding method of claim 11 , wherein each weight is determined based on a direction of the current block.
13. The video decoding method of claim 12 , wherein the direction of the current block is divided into a horizontal direction and a vertical direction.
14. The video decoding method of claim 7 , wherein the generating of the final prediction value includes generating the final prediction value by averaging the first prediction value and the second prediction value.
15. The video decoding method of claim 7 , further comprising adding the residual value for the current pixel to the final prediction value to generate a reconstructed image.