Method and apparatus for intra prediction within display screen
The present invention relates to a method and apparatus for intra prediction. The intra prediction method for a decoder, according to the present invention, comprises the steps of entropy-decoding a received bitstream, generating reference pixels to be used in the intra prediction of a prediction unit; generating a prediction block from the reference pixels on the basis of a prediction mode for the prediction unit and reconstructing an image from the prediction block and a residual block, which is obtained as a result of entropy encoding, wherein the reference pixels and/or the prediction block pixels are predicted on the basis of a base pixel, and the predicted pixel value can be the sum of the pixel value of the base pixel and the difference between the pixel values of the base pixel and the generated pixel.
1. A method of decoding a video signal with a decoding apparatus, the method comprising:
obtaining a residual coefficient of a current block;
deriving an inverse-quantized residual coefficient by performing an inverse-quantization on the residual coefficient of the current block;
deriving a residual sample of the current block from the inverse-quantized residual coefficient of the current block;
deriving reference samples for intra prediction of the current block based on at least one of neighboring samples adjacent to the current block;
obtaining a prediction sample of the current block by performing the intra prediction for a target prediction position of the current block based on a top reference sample having a same x-coordinate as the target prediction position and a variation relating to the reference samples,
wherein the variation relating to the reference samples is representative of a difference value between a reconstructed value of a top-left reference sample whose a location is fixed regardless of a coordinate of the target prediction position and a reconstructed value of a left reference sample whose a location is determined dependent on the coordinate of the target prediction position, the left reference sample having a same y-coordinate as the target prediction position; and
deriving a reconstruction sample of the current block by adding the prediction sample and the residual sample.
2. The method of claim 1 , wherein the prediction sample is included in a most left column of the current block.