Image encoding/decoding method using prediction block and apparatus for same
According to the present invention, an image encoding/decoding method comprises the steps of: performing an intra prediction on a current block so as to generate a prediction block; performing filtering on a filtering target pixel in the prediction block on the basis of the intra prediction mode of the current block so as to generate a final prediction block; and generating a reconstructed block on the basis of a reconstructed differential block corresponding to the current block and on the final prediction block. According to the present invention, image encoding/decoding efficiency can be improved.
1. A video decoding apparatus comprising:
a prediction block generating unit to generate a prediction block by performing intra prediction on a current block by performing filtering on a filtering target pixel in the prediction block, respectively, and by using at least one of a predetermined filter shape, a predetermined filter tap and a predetermined plurality of filter coefficients fixed regardless of a size of the current block for the filtering when intra prediction mode of the current block is a DC mode; and
a reconstructed block generating unit to generate a reconstructed block based on the prediction block and a reconstructed residual block corresponding to the current block, and
wherein the filtering target pixel comprises a left vertical prediction pixel line that is one vertical pixel line positioned at a leftmost side of the prediction block and an upper horizontal prediction pixel line that is one horizontal pixel line positioned at an uppermost side of the prediction block.
2. The video decoding apparatus of claim 1 , wherein when the intra prediction mode of the current block is the DC mode and the filtering target pixel is a left upper prediction pixel positioned at a leftmost upper side of the prediction block,
the filtering is performed on the filtering target pixel by applying a 3-tap filter based on the filtering target pixel, an upper reference pixel adjacent to an upper portion of the filtering target pixel, and a left reference pixel adjacent to a left of the filtering target pixel,
the upper reference pixel and the left reference pixel being reconstructed reference pixels each adjacent to the current block, and
in the 3-tap filter, a filter coefficient allocated to a filter tap corresponding to the filtering target pixel being 2/4, a filter coefficient allocated to a filter tap corresponding to the upper reference pixel being ¼, and a filter coefficient allocated to a filter tap corresponding to the left reference pixel being ¼.
3. The video decoding apparatus of claim 1 , wherein the intra prediction mode of the current block is the DC mode when the filtering is performed when the current block has a size of smaller than 32×32.
4. A video encoding apparatus comprising:
a prediction block generating unit to generate a prediction block by performing intra prediction on a current block by performing filtering on a filtering target pixel in the prediction block, and by using at least one of a predetermined filter shape, a predetermined filter tap and a predetermined plurality of filter coefficients fixed regardless of a size of the current block for the filtering when intra prediction mode of the current block is a DC mode; and
a reconstructed block generating unit to generate a reconstructed block based on the prediction block and a reconstructed residual block corresponding to the current block, and
wherein the filtering target pixel comprises a left vertical prediction pixel line that is one vertical pixel line positioned at a leftmost side of the prediction block and an upper horizontal prediction pixel line that is one horizontal pixel line positioned at an uppermost side of the prediction block.
5. The video encoding apparatus of claim 4 , wherein when the intra prediction mode of the current block is the DC mode and the filtering target pixel is a left upper prediction pixel positioned at a leftmost upper side of the prediction block,
the filtering is performed on the filtering target pixel by applying a 3-tap filter based on the filtering target pixel, an upper reference pixel adjacent to an upper portion of the filtering target pixel, and a left reference pixel adjacent to a left of the filtering target pixel,
the upper reference pixel and the left reference pixel being reconstructed reference pixels each adjacent to the current block, and
in the 3-tap filter, a filter coefficient allocated to a filter tap corresponding to the filtering target pixel being 2/4, a filter coefficient allocated to a filter tap corresponding to the upper reference pixel being ¼, and a filter coefficient allocated to a filter tap corresponding to the left reference pixel being ¼.
6. The video decoding apparatus of claim 4 , wherein the intra prediction mode of the current block is the DC mode when the filtering is performed when the current block has a size of smaller than 32×32.
7. A non-transitory computer-readable medium storing a bitstream, the bitstream comprising:
prediction mode information indicating a prediction mode for a current block, wherein
a prediction block is generated by performing intra prediction on the current block by performing filtering on a filtering target pixel in the prediction block, and by using at least one of a predetermined filter shape, a predetermined filter tap and a predetermined plurality of filter coefficients fixed regardless of a size of the current block for the filtering when intra prediction mode of the current block indicated by the prediction mode information is a DC mode,
a reconstructed block is generated based on the prediction block and a reconstructed residual block corresponding to the current block, and
the filtering target pixel comprises a left vertical prediction pixel line that is one vertical pixel line positioned at a leftmost side of the prediction block and an upper horizontal prediction pixel line that is one horizontal pixel line positioned at an uppermost side of the prediction block.
8. The non-transitory computer-readable medium of claim 7 , wherein when the intra prediction mode of the current block is the DC mode and the filtering target pixel is a left upper prediction pixel positioned at a leftmost upper side of the prediction block,
the filtering is performed on the filtering target pixel by applying a 3-tap filter based on the filtering target pixel, an upper reference pixel adjacent to an upper portion of the filtering target pixel, and a left reference pixel adjacent to a left of the filtering target pixel,
the upper reference pixel and the left reference pixel being reconstructed reference pixels each adjacent to the current block, and
in the 3-tap filter, a filter coefficient allocated to a filter tap corresponding to the filtering target pixel being 2/4, a filter coefficient allocated to a filter tap corresponding to the upper reference pixel being ¼, and a filter coefficient allocated to a filter tap corresponding to the left reference pixel being ¼.
9. The non-transitory computer-readable medium of claim 7 , wherein the intra prediction mode of the current block is the DC mode when the filtering is performed when the current block has a size of smaller than 32×32.