Video encoding method with intra prediction using checking process for unified reference possibility, video decoding method and device thereof
An intra prediction method includes searching for a neighboring block restored prior to a current block from among blocks of an image; checking whether the neighboring block found by the searching is a block restored in an intra mode and whether an intra mode of the current block is also a Combined Intra Prediction (CIP) mode in which only blocks pre-restored in the intra mode are referred to; determining based on a checking result of the checking whether the found neighboring block is a reference block available for intra prediction of the current block; and performing intra prediction on the current block by using sample values of the reference block determined as available for the intra prediction of the current block.
1. An intra prediction method comprising:
searching for a neighboring block restored prior to a current block from among blocks of an image;
checking whether the neighboring block found by the searching is a block restored in an intra mode and whether an intra mode of the current block is also a Combined Intra Prediction (CIP) mode in which only blocks pre-restored in the intra mode are referred to;
determining based on a checking result of the checking whether the found neighboring block is a reference block available for intra prediction of the current block; and
performing intra prediction on the current block by using sample values of the reference block determined as available for the intra prediction of the current block.
2. The intra prediction method of claim 1 , wherein the searching for the neighboring block comprises searching for neighboring blocks restored prior to the current block before determining whether a prediction mode of the current block is an intra mode of the CIP mode, and
the checking comprises checking whether each of the neighboring blocks found by the searching is restored in the intra mode and whether the intra mode of the current block is also the CIP mode.
3. The intra prediction method of claim 1 , wherein the performing of the intra prediction comprises padding a region deviating from a boundary of the image with a sample value of a pixel adjacent to an inside of the boundary from among pixels of the reference block when the reference block deviates from the boundary of the image.
4. The intra prediction method of claim 3 , wherein the performing of the intra prediction further comprises padding the region deviating from the boundary of the image with the sample value of the pixel adjacent to the inside of the boundary from among the pixels of the reference block when the reference block deviates from the boundary of the image regardless of whether the intra mode of the current block is the CIP mode.
5. An intra prediction apparatus comprising:
an intra reference block determiner configured to search for a neighboring block restored prior to a current block from among blocks of an image and determine whether the neighboring block found by the searching is a reference block available for intra prediction of the current block, based on a result of checking whether the found neighboring block is a block restored in an intra mode and whether an intra mode of the current block is also a Combined Intra Prediction (CIP) mode in which only blocks pre-restored in the intra mode are referred to; and
an intra predictor configured to perform intra prediction on the current block by using sample values of the reference block determined as available for the intra prediction of the current block.
6. The intra prediction apparatus of claim 5 , wherein the intra reference block determiner searches for neighboring blocks restored prior to the current block before determining whether a prediction mode of the current block is an intra mode of the CIP mode and checks whether each of the neighboring blocks found by the searching is restored in the intra mode and whether the intra mode of the current block is also the CIP mode.
7. The intra prediction apparatus of claim 5 , wherein the intra predictor pads a region deviating from a boundary of the image with a sample value of a pixel adjacent to an inside of the boundary from among pixels of the reference block when the reference block deviates from the boundary of the image.
8. The intra prediction apparatus of claim 7 , wherein the intra predictor pads the region deviating from the boundary of the image with the sample value of the pixel adjacent to the inside of the boundary from among the pixels of the reference block when the reference block deviates from the boundary of the image regardless of whether the intra mode of the current block is the CIP mode.
9. A video decoding apparatus comprising:
a parser configured to restore samples by performing entropy decoding on a bit string parsed from a received bitstream;
an inverse transformer configured to restore samples by performing inverse quantization and inverse transformation on a quantized transformation coefficient from among the restored samples;
an intra predictor configured to search for a neighboring block restored prior to a current block, determine whether the neighboring block found by the searching is a reference block available for intra prediction of the current block based on a result of checking whether the found neighboring block is a block restored in an intra mode and whether an intra mode of the current block is also a Combined Intra Prediction (CIP) mode in which only blocks pre-restored in the intra mode are referred to, and perform intra prediction on the current block by using sample values of the reference block determined as available for the intra prediction of the current block, to perform the intra prediction on the current block that is in the intra mode from among the samples;
a motion compensator configured to perform motion compensation on blocks in an inter prediction mode from among the samples; and
a restorer configured to restore an image by using blocks restored by the inter prediction or the intra prediction.
10. The video decoding apparatus of claim 9 , wherein the intra predictor is configured to search for neighboring blocks restored prior to the current block before determining based on CIP mode information of a current image parsed from the bitstream whether a prediction mode of the current block is an intra mode of the CIP mode, and check whether each of the neighboring blocks found by the searching is restored in the intra mode and whether the intra mode of the current block is also the CIP mode.
11. The video decoding apparatus of claim 9 , wherein the intra predictor is configured to pad a region deviating from a boundary of the image with a sample value of a pixel adjacent to an inside of the boundary from among pixels of the reference block when the reference block deviates from the boundary of the image regardless of whether the intra mode of the current block is the CIP mode.
12. A video encoding apparatus comprising:
an intra predictor configured to search for a neighboring block restored prior to a current block, determine whether the neighboring block found by the searching is a reference block available for intra prediction of the current block based on a result of checking whether the found neighboring block is a block restored in an intra mode and whether an intra mode of the current block is also a Combined Intra Prediction (CIP) mode in which only blocks pre-restored in the intra mode are referred to, and perform intra prediction on the current block by using sample values of the reference block determined to be available for the intra prediction of the current block, to perform the intra prediction on the current block that is in the intra mode from among blocks of a video;
an inter predictor configured to perform inter prediction on blocks in an inter prediction mode from among the blocks;
a transformer and quantizer configured to perform transformation and quantization on a result of performing the intra prediction or the inter prediction; and
an output unit configured to output a bitstream generated by performing entropy encoding on samples including a quantized transformation coefficient generated as a result of the transformation and quantization.
13. The video encoding apparatus of claim 12 , wherein the intra predictor is configured to search for neighboring blocks restored prior to the current block before determining based on CIP mode information of a current image parsed from the bitstream whether a prediction mode of the current block is an intra mode of the CIP mode, and check whether each of the neighboring blocks found by the searching is restored in the intra mode and whether the intra mode of the current block is also the CIP mode.
14. The video encoding apparatus of claim 12 , wherein the intra predictor is configured to pad a region deviating from a boundary of the image with a sample value of a pixel adjacent to an inside of the boundary from among pixels of the reference block when the reference block deviates from the boundary of the image regardless of whether the intra mode of the current block is the CIP mode.
15. A non-transitory computer-readable recording medium having recorded thereon a program which causes a computer to perform an intra prediction method comprising:
searching for a neighboring block restored prior to a current block from among blocks of an image;
checking whether the neighboring block found by the searching is a block restored in an intra mode and whether an intra mode of the current block is also a Combined Intra Prediction (CIP) mode in which only blocks pre-restored in the intra mode are referred to;
determining based on a checking result of the checking whether the found neighboring block is a reference block available for intra prediction of the current block; and
performing intra prediction on the current block by using sample values of the reference block determined as available for the intra prediction of the current block.