Video encoding/decoding method and device using BDPCM, and method for transmitting bitstream

1. An image decoding method performed by an image decoding apparatus, the image decoding method comprising:

parsing, from a bitstream, first information specifying whether block difference pulse code modulation (BDPCM) applies to an intra-predicted current block;

determining a prediction direction of BDPCM for the current block and generating a residual block of the current block based on the determined prediction direction of BDPCM, based on the first information specifying that BDPCM applies to the current block;

generating a prediction block of the current block, by performing intra prediction based on an intra prediction mode of the current block; and

reconstructing the current block based on the residual block and the prediction block,

wherein the prediction direction of BDPCM and a prediction direction of the intra prediction mode are the same.

2. The image decoding method of claim 1 ,

wherein the first information is parsed only based on a non-zero residual signal being present in the current block, and

wherein, based on the non-zero residual signal being not present in the current block, parsing of the first information is skipped and it is determined that BDPCM does not applies to the current block.

3. The image decoding method of claim 2 , wherein whether the non-zero residual signal is present in the current block is determined based on information parsed from the bitstream.

4. The image decoding method of claim 1 , wherein the prediction direction of BDPCM is determined based on second information parsed from the bitstream.

5. The image decoding method of claim 1 , wherein the prediction direction of BDPCM is determined based on the intra prediction mode.

6. The image decoding method of claim 5 ,

wherein the prediction direction of BDPCM is determined to be a vertical direction, based on the prediction direction of the intra prediction mode being a vertical direction,

wherein the prediction direction of BDPCM is determined to be a horizontal direction, based on the prediction direction of the intra prediction mode being a horizontal direction, and

wherein the prediction direction of BDPCM is determined to be a predetermined direction, based on the prediction direction of the intra prediction mode being a non-directional mode.

7. The image decoding method of claim 6 , wherein the predetermined direction is a predefined direction or a direction derived based on information signaled at a higher level of the current block.

8. The image decoding method of claim 1 , wherein the prediction direction of BDPCM is determined based on a size of the current block.

9. The image decoding method of claim 8 , wherein, in case a width of the current block is W and a height is H,

the prediction direction of BDPCM is determined to be a horizontal direction based on W being greater than H, and

the prediction direction of BDPCM is determined to be a vertical direction based on H being greater than W.

10. The image decoding method of claim 8 , wherein, in case a width of the current block is W and a height is H,

the prediction direction of BDPCM is determined to be a vertical direction based on W/H being equal to or greater than a predetermined integer N, and

the prediction direction of BDPCM is determined to be a horizontal direction based on W/H being equal to or less than 1/N.

11. An image decoding apparatus comprising:

a memory; and

at least one processor,

wherein the at least one processor is configured to:

parse, from a bitstream, first information specifying whether block difference pulse code modulation (BDPCM) applies to an intra-predicted current block;

determine a prediction direction of BDPCM for the current block and generate a residual block of the current block based on the determined prediction direction of BDPCM, based on the first information specifying that BDPCM applies to the current block;

generate a prediction block of the current block, by performing intra prediction based on an intra prediction mode of the current block; and

reconstruct the current block based on the residual block and the prediction block,

wherein the prediction direction of BDPCM and a prediction direction of the intra prediction mode are the same.

12. An image encoding method performed by an image encoding apparatus, the image encoding method comprising:

determining whether block difference pulse code modulation (BDPCM) applies to a current block;

determining a prediction direction of BDPCM for the current block based on BDPCM applying to the current block;

generating a prediction block of the current block, by performing intra prediction, based on an intra prediction mode of the current block;

generating a residual block of the current block based on the prediction block;

encoding a residual block of the current block based on the determined prediction direction of BDPCM; and

encoding first information specifying whether BDPCM applies to the current block,

wherein the prediction direction of BDPCM and a prediction direction of the intra prediction mode are the same.

13. A method of transmitting a bitstream generated by the image encoding method of claim 12 .