Method and device for encoding/decoding image, and recording medium in which bitstream is stored
An image encoding/decoding method and apparatus for performing intra prediction using a plurality of reference sample lines are provided. An image decoding method may comprise configuring a plurality of reference sample lines, reconstructing an intra prediction mode of a current block, and performing intra prediction for the current block based on the intra prediction mode and the plurality of reference sample lines.
1. An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
determining an intra prediction mode of a current block;
constructing a reference sample for intra prediction of the current block based on a reference sample line selected from a plurality of reference sample lines adjacent to the current block;
performing filtering on the constructed reference sample;
determining an interpolation filter for the intra prediction; and
obtaining prediction samples for the current block based on the intra prediction mode, the filtered reference sample, and the interpolation filter,
wherein the interpolation filter is determined based on at least one of a size of the current block, the selected reference sample line, and the intra prediction mode of the current block,
wherein the reference sample line is selected based on a reference sample line indicator indicating one among the plurality of reference sample lines adjacent to the current block,
wherein the reference sample line indicator is signaled as being included in a bitstream, and
wherein, based on an upper boundary of the current block being identical to an upper boundary of a current coding tree block, the reference sample line indicator is not included in the bitstream.
2. The image decoding method of claim 1 , wherein the filtering on the constructed reference sample is performed based on the selected reference sample line being a first reference sample line adjacent to the current block.
3. The image decoding method of claim 1 , wherein the reference sample line is selected among the plurality of reference sample lines adjacent to the current block based on a color component of the current block.
4. The image decoding method of claim 1 , wherein based on a color component of the current block being a luma component, the interpolation filter is a 4-tap filter, and wherein based on the color component of the current block being a chroma component, the interpolation filter is a 2-tap filter.
5. An image encoding method performed by an image encoding apparatus, the image encoding method comprising:
determining an intra prediction mode of a current block;
constructing a reference sample for intra prediction of the current block based on a reference sample line selected from a plurality of reference sample lines adjacent to the current block;
performing filtering on the constructed reference sample;
determining an interpolation filter for the intra prediction;
obtaining prediction samples for the current block based on the intra prediction mode, the filtered reference sample, and the interpolation filter; and
encoding image information including intra prediction mode information and reference sample line information,
wherein the interpolation filter is determined based on at least one of a size of the current block, the selected reference sample line, and the intra prediction mode of the current block,
wherein the encoding image information comprises encoding a reference sample line indicator indicating the reference sample line selected from the plurality of reference sample lines adjacent to the current block into a bitstream, and
wherein, based on an upper boundary of the current block being identical to an upper boundary of a current coding tree block, the reference sample line indicator is not included in the bitstream.
6. The image encoding method of claim 5 , wherein the filtering on the constructed reference sample is performed based on the selected reference sample line being a first reference sample line adjacent to the current block.
7. The image encoding method of claim 5 , wherein the reference sample line is selected among the plurality of reference sample lines adjacent to the current block based on a color component of the current block.
8. The image encoding method of claim 5 , wherein based on a color component of the current block being a luma component, the interpolation filter is a 4-tap filter, and wherein based on the color component of the current block being a chroma component, the interpolation filter is a 2-tap filter.
9. 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 determining an intra prediction mode of a current block, constructing a reference sample for intra prediction of the current block based on a reference sample line selected from a plurality of reference sample lines adjacent to the current block, performing filtering on the constructed reference sample, determining an interpolation filter for the intra prediction, obtaining prediction samples for the current block based on the intra prediction mode, the filtered reference sample, and the interpolation filter, and encoding image information including intra prediction mode information and reference sample line information, and
transmitting the image data comprising the bitstream, wherein the interpolation filter is determined based on at least one of a size of the current block, the selected reference sample line, and the intra prediction mode of the current block,
wherein the encoding image information comprises encoding a reference sample line indicator indicating the reference sample line selected from the plurality of reference sample lines adjacent to the current block into a bitstream, and
wherein, based on an upper boundary of the current block being identical to an upper boundary of a current coding tree block, the reference sample line indicator is not included in the bitstream.
10. The transmitting method of claim 9 , wherein the filtering on the constructed reference sample is performed based on the selected reference sample line being a first reference sample line adjacent to the current block.
11. The transmitting method of claim 9 , wherein the reference sample line is selected among the plurality of reference sample lines adjacent to the current block based on a color component of the current block.
12. The transmitting method of claim 9 , wherein based on a color component of the current block being a luma component, the interpolation filter is a 4-tap filter, and wherein based on the color component of the current block being a chroma component, the interpolation filter is a 2-tap filter.