We Claim:-
1. An image decoding method performed by an image decoding apparatus, the image
decoding method comprising:
deriving prediction samples for the current block based on an intra prediction mode for
a current block;
performing filtering on the prediction samples; and
generating a reconstructed picture based on residual samples for the current block and
the prediction samples,
wherein based on the current block being a luma block, an intra prediction mode for the
luma block is derived using an intra prediction mode for a neighboring block of the luma block,
wherein based on the intra prediction mode for the neighboring block not being
available, the intra prediction mode for the neighboring block is set to a planar mode; and
wherein the filtering is performed based on the intra prediction mode of the current
block, a size of the current block, and a position of a prediction sample.
2. The image decoding method of claim 1, wherein the filtering is performed based
on the intra prediction mode for the current block being a planar mode.
3. The image decoding method of claim 1, wherein based on the current block being
a chroma block, an intra prediction mode for the chroma block is derived using an intra
prediction mode of a corresponding luma position corresponding to a specific position of the
chroma block.
4. The image decoding method of claim 3, wherein based on a luma position
corresponding to a top-left position of the chroma block being (x, y), the corresponding luma
position is derived as (x + width of a corresponding luma block/2, y + height of the
corresponding luma block/2).
5. The image decoding method of claim 1, wherein the number of intra prediction
modes for the luma block and the number of intra prediction modes for the chroma block are
different.
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6. An image encoding method performed by an image encoding apparatus, the image
encoding method comprising:
deriving prediction samples for the current block based on an intra prediction mode for
a current block;
performing filtering on the prediction samples;
deriving residual samples for the current block based on the prediction samples; and
encoding image information including residual information related to the residual
samples,
wherein based on the current block being a luma block, an intra prediction mode for the
luma block is derived using an intra prediction mode for a neighboring block of the luma block,
wherein based on the intra prediction mode for the neighboring block not being
available, the intra prediction mode for the neighboring block is set to a planar mode; and
wherein the filtering is performed based on the intra prediction mode of the current
block, a size of the current block, and a position of a prediction sample.
7. The image encoding method of claim 6, wherein the filtering is performed based
on the intra prediction mode for the current block being a planar mode.
8. The image encoding method of claim 6, wherein based on the current block being
a chroma block, an intra prediction mode for the chroma block is derived using an intra
prediction mode of a corresponding luma position corresponding to a specific position of the
chroma block.
9. The image encoding method of claim 7, wherein based on a luma position
corresponding to a top-left position of the chroma block being (x, y), the corresponding luma
position is derived as (x + width of a corresponding luma block/2, y + height of the
corresponding luma block/2).
10. A transmitting method for image data, the method comprising:
obtaining a bitstream of encoded image information, wherein the encoded image
information is generated based on deriving prediction samples for the current block based on
an intra prediction mode for a current block, performing filtering on the prediction sample,
deriving residual samples for the current block based on the prediction samples, and encoding
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image information including residual information related to the residual samples, and
transmitting the image data comprising the bitstream,
wherein based on the current block being a luma block, an intra prediction mode for the
luma block is derived using an intra prediction mode for a neighboring block of the luma block,
wherein based on the intra prediction mode for the neighboring block not being
available, the intra prediction mode for the neighboring block is set to a planar mode; and
wherein the filtering is performed based on the intra prediction mode of the current
block, a size of the current block, and a position of a prediction sample.