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, comprising:
deriving reference samples based on neighboring samples adjacent to a current block, the reference samples being used for an intra prediction of the current block;
performing the intra prediction on the current block based on the reference samples;
deriving a reconstruction sample of the current block using a prediction sample derived by performing the intra prediction and a residual sample relating to the current block; and
applying a deblocking filter to the reconstruction sample of the current block,
wherein deriving the reference samples comprises:
determining, based on a prediction mode of a neighboring block, whether at least one of the neighboring samples included in the neighboring block is an unavailable sample, the prediction mode specifying whether the neighboring block is coded in an inter prediction or the intra prediction; and
performing a substitution for the unavailable sample which is not used for the intra prediction of the current block by using a sample located on one side of the unavailable sample among the neighboring samples adjacent to the current block when the unavailable sample is present among the neighboring samples adjacent to the current block,
wherein when the unavailable sample corresponds to at least one of left neighboring samples other than a top-left neighboring sample, the substitution of the unavailable sample is performed using only a bottom neighboring sample of the unavailable sample, without referring to a top neighboring sample of the unavailable sample, and
wherein when the unavailable sample corresponds to at least one of top neighboring samples, the substitution of the unavailable sample is performed using a left neighboring sample of the unavailable sample.
2. The method of claim 1 , wherein determination of whether the at least one of neighboring samples is the unavailable sample is based on a constrained intra prediction flag in addition to the prediction mode relating to the neighboring block, the constrained intra prediction flag specifying whether at least one of the neighboring samples included in the neighboring block coded in the inter prediction is used for the intra prediction of the current block.
3. The method of claim 2 , wherein when the prediction mode relating to the neighboring block indicates that the neighboring block is coded in the inter prediction and a value of the constrained intra prediction flag is set to 1, the neighboring sample included in the neighboring block is determined to be the unavailable sample.