Method and device for encoding and decoding image
A method for decoding an image according to the present invention comprises the steps of: restoring a residual block by performing inverse quantization and inverse transformation for the entropy-decoded residual block; generating a prediction block by performing intra prediction for a current block; and restoring an image by adding the restored residual block to the prediction block, wherein the step of generating the prediction block further comprises a step for generating a final prediction value of a pixel to be predicted, on the basis of a first prediction value of the pixel to be predicted, which is included in the current block, and of a final correction value that is calculated by performing an arithmetic right shift by a binary digit I for a two's complement integer representation with respect to an initial correction value of the pixel to be predicted. The operational complexity during image encoding/decoding can be reduced.
1. A video decoding method comprising:
generating a prediction block by performing intra prediction for a current block; and
reconstructing a picture based on a reconstructed residual block and the prediction block,
wherein the generating the prediction block comprising
obtaining a first prediction value of a prediction target pixel of the prediction block;
determining an initial correction value of the prediction target pixel;
calculating a final correction value of the prediction target pixel by performing an arithmetic right shift on the initial correction value by a binary digit of 1; and
generating a final prediction value of the prediction target pixel based on the first prediction value and the final correction value.
2. The video decoding method of claim 1 , wherein whether to correct the first prediction value is determined depending on encoding information on the current block and a position of the prediction target pixel in the prediction block and the final prediction value of the prediction target pixel is generated based on a result of the determination.
3. The video decoding method of claim 2 , wherein the encoding information comprises at least one of an intra prediction mode, luma signal information, chroma signal information and a block size of the current block.
4. The video decoding method of claim 2 , wherein a pixel on a left boundary of the current block is corrected when an intra prediction mode of the current block is a vertical prediction mode.
5. A video encoding method comprising:
generating a prediction block by performing intra prediction for a current block; and
obtaining a residual block based on the current block and the prediction block,
wherein the generating the prediction block comprising
obtaining a first prediction value of a prediction target pixel of the prediction block;
determining an initial correction value of the prediction target pixel;
calculating a final correction value of the prediction target pixel by performing an arithmetic right shift on the initial correction value by a binary digit of 1; and
generating a final prediction value of the prediction target pixel based on the first prediction value and the final correction value.
6. The video encoding method of claim 5 , wherein whether to correct the first prediction value is determined depending on encoding information on the current block and a position of the prediction target pixel in the prediction block and the final prediction value of the prediction target pixel is generated based on a result of the determination.
7. The video encoding method of claim 6 , wherein the encoding information comprises at least one of an intra prediction mode, luma signal information, chroma signal information and a block size of the current block.
8. The video encoding method of claim 6 , wherein a pixel on a left boundary of the current block is corrected when an intra prediction mode of the current block is a vertical prediction mode.