Method and apparatus for performing intra-prediction using adaptive filter
Provided is a method and apparatus for performing intra-prediction using an adaptive filter. The method for performing intra-prediction includes the steps of: determining whether or not to apply a first filter for a reference pixel value on the basis of information of a neighboring block of a current block; applying the first filter for the reference pixel value when it is determined to apply the first filter; performing intra-prediction on the current block on the basis of the reference pixel value; determining whether or not to apply a second filter for a prediction value according to each prediction mode of the current block, which is predicted by the intra-prediction performance on the basis of the information of the neighboring block; and applying the second filter for the prediction value according to each prediction mode of the current block when it is determined to apply the second filter.
1. A video decoding apparatus, comprising:
a processor to determine whether to apply a first filter to a reference pixel value of a current block based on at least one of an intra prediction mode of the current block and a size of the current block and to derive a prediction value of the current block using the reference pixel value,
wherein the processor determines whether to apply a second filter to the prediction value of the current block based on at least one of an intra prediction mode of the current block and a size of the current block, for thereby producing a filtered prediction value,
wherein when the intra prediction mode of the current block is a DC mode, the processor, as the second filter, applies a 3-tap filter to an upper-leftmost pixel of the current block among the prediction pixels of the current block and applies a 2-tap filter to remaining uppermost and leftmost pixels except the upper-leftmost pixel among the prediction pixels of the current block, and
wherein the upper-leftmost pixel corresponds to a first filter coefficient and the remaining uppermost and leftmost pixels correspond to a second filter coefficient, wherein the second filter coefficient is 1.5 times larger than the first filter coefficient.
2. The video decoding apparatus of claim 1 , wherein the intra prediction mode of the current block is determined based on a Most Probable Mode (MPM).
3. A video encoding apparatus comprising:
a processor to encode information related to whether to apply a first filter to a reference pixel value of a current block and perform intra-prediction for the current block based on the reference pixel value,
wherein the processor encode information related to whether to apply a second filter to a prediction value of the current block, wherein the information related to whether to apply the first filter is related to at least one of an intra prediction mode of the current block and a size of the current block,
wherein the information related to whether to apply the second filter is related to at least one of the intra prediction mode of the current block and the size of the current block,
wherein when the intra prediction mode of the current block is a DC mode, as the second filter, a 3-tap filter is applied to an upper-leftmost pixel of the current block among prediction pixels of the current block and a 2-tap filter is applied to remaining uppermost and leftmost pixels except the upper-leftmost pixel among the prediction pixels of the current block, and
wherein the upper-leftmost pixel corresponds to a first filter coefficient and the remaining uppermost and leftmost pixels correspond to a second filter coefficient, wherein the second filter coefficient is 1.5 times larger than the first filter coefficient.
4. A non-transitory computer-readable storage medium storing a bitstream, the bitstream comprising:
information related to whether to apply a first filter to a reference pixel value of a current block; and
information related to whether to apply a second filter to a prediction value of the current block,
wherein the information related to whether to apply the first filter is related to at least one of an intra prediction mode of the current block and a size of the current block,
wherein the information related to whether to apply the second filter is related to at least one of the intra prediction mode of the current block and the size of the current block,
wherein when the intra prediction mode of the current block is a DC mode, as the second filter, a 3-tap filter is applied to an upper-leftmost pixel of the current block among prediction pixels of the current block and a 2-tap filter is applied to remaining uppermost and leftmost pixels except the upper-leftmost pixel among the prediction pixels of the current block, and
wherein the upper-leftmost pixel corresponds to a first filter coefficient and the remaining uppermost and leftmost pixels correspond to a second filter coefficient, wherein the second filter coefficient is 1.5 times larger than the first filter coefficient.