# US 2019/0356923 A1 · Video encoding apparatus, video decoding apparatus, and video decoding method for performing intra-prediction based on directionality of neighboring block > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0356923 A1 - Document ID: US20190356923A1 - Status: Published application - Kind: A1 - Application number: 16/532,208 - Filed: 2019-08-05 - Published: 2019-11-21 - Earliest claimed: 2009-12-30 - Assignees: Ideahub Inc. - Applicants: Ideahub Inc. - Inventors: Je Chang JEONG; Soon Jong JIN; Sang Jun PARK; Hyuk LEE - Web page: https://patentgrep.com/patent/US20190356923A1 ## CPC - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/11: among a plurality of spatial predictive coding modes - H04N 19/124: Quantisation - H04N 19/152: by measuring the fullness of the transmission buffer - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/197: {including determination of the initial value of an encoding parameter (H04N19/56 takes precedence)} - H04N 19/513: Processing of motion vectors - H04N 19/547: Motion estimation performed in a transform domain - H04N 19/61: in combination with predictive coding - H04N 19/184: the unit being bits, e.g. of the compressed video stream - H04N 19/50: using predictive coding (H04N19/61 takes precedence) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Provided are methods and apparatuses for improving compression efficiency in directional intra-prediction. A video encoding apparatus, which does not need to record intra mode information, includes a mode selector that selects one from among a plurality of intra modes on the basis of a directionality of at least one neighboring block that has already been reconstructed before a current block is reconstructed, an intra predictor that obtains a prediction block of the current block from the at least one neighboring block according to the directionality of the selected mode, and obtains a residual block by subtracting the prediction block from the current block, and a unit for encoding the obtained residual block. ## Claims ### Claim at position 1 1-19. (canceled) ### Claim 20 A video encoding method performed by a video encoding apparatus, the method comprising: determining a current intra prediction mode associated with a current block; performing intra-prediction according to the current intra prediction mode associated with the current block to generate a prediction block associated with the current block; determining a neighboring intra prediction mode associated with a neighboring block, the neighboring block being adjacent to the current block; encoding the current intra prediction mode associated with the current block based on whether the neighboring intra prediction mode associated with the neighboring block has directionality or not; obtaining a residual block associated with the current block by using the prediction block and the current block; transforming the residual block to generate transform coefficients using a discrete cosine transform; quantizing the transform coefficients to generate quantized transform coefficients; encoding the quantized transform coefficients, wherein the encoding the current intra prediction mode associated with the current block comprises: encoding the current intra prediction mode associated with the current block according to a first set of two or more mathematical expressions, when the neighboring intra prediction mode associated with the neighboring block has no directionality, encoding the current intra prediction mode associated with the current block according to a second set of two or more mathematical expressions, when the neighboring intra prediction mode associated with the neighboring block has directionality, wherein the second set of two or more mathematical expressions is different from the first set of two or more mathematical expressions, and the neighboring block includes a left block adjacent to the current block. ### Claim 21 (depends on 20) The video encoding method of claim 20, wherein an intra prediction mode having no directionality includes a planar mode or a DC mode. ### Claim 22 (depends on 20) The video encoding method of claim 20, wherein the second set of two or more mathematical expressions use the neighboring intra prediction mode associated with the neighboring block. ### Claim 23 (depends on 20) The video encoding method of claim 20, wherein the encoding the current intra prediction mode associated with the current block comprises: determining candidate intra prediction modes based on whether the neighboring intra prediction mode associated with the neighboring block has directionality or not; and encoding the current intra prediction mode associated with the current block among the candidate intra prediction modes. ### Claim 24 (depends on 23) The video encoding method of claim 23, wherein the candidate intra prediction modes are determined by using the first set of two or more mathematical expressions, when the neighboring intra prediction mode associated with the neighboring block has no directionality, and wherein the candidate intra prediction modes are determined by using the second set of two or more mathematical expressions, when the neighboring intra prediction mode associated with the neighboring block has directionality. ### Claim 25 (depends on 24) The video encoding method of claim 24, wherein the encoding the current intra prediction mode associated with the current block among the candidate intra prediction modes comprises: identifying the current intra prediction mode associated with the current block among the candidate intra prediction modes; and encoding information for identifying the current intra prediction mode associated with the current block among the candidate intra prediction modes. ### Claim 26 (depends on 20) The video encoding method of claim 20, wherein encoding the quantized transform coefficients comprises: encoding the quantized transform coefficients to generate a bitstream. ### Claim 27 (depends on 26) The video encoding method of claim 26, wherein encoding the quantized transform coefficients comprises: losslessly encoding the quantized transform coefficients to generate the bitstream. ### Claim 28 (depends on 20) The video encoding method of claim 20, wherein obtaining the residual block comprises: subtracting the prediction block from the current block to obtain a residual block associated with the current block. ### Claim 29 A non-transitory computer-readable recording medium storing a bitstream that is received by an image decoding apparatus and used to reconstruct a current block included in an image, wherein the bitstream comprises information on a neighboring intra prediction mode associated with a neighboring block and information on a residual block associated with the current block, the neighboring block being adjacent to the current block, the information on the neighboring intra prediction mode associated with the neighboring block is decoded and used to reconstruct a neighboring intra prediction mode associated with the neighboring block, the neighboring intra prediction mode associated with the neighboring block is used to determine a current intra prediction mode associated with the current block based on whether the neighboring intra prediction mode associated with the neighboring block has directionality or not, the current intra prediction mode associated with the current block is used to perform intra-prediction to generate a prediction block associated with the current block; the information on the residual block associated with the current block is decoded and used to obtain a residual block associated with the current block, the prediction block and the residual block are used to reconstruct the current block, wherein when the neighboring intra prediction mode associated with the neighboring block has no directionality, the current intra prediction mode associated with the current block is determined according to a first set of two or more mathematical expressions, when the neighboring intra prediction mode associated with the neighboring block has directionality, the current intra prediction mode associated with the current block is determined according to a second set of two or more mathematical expressions, wherein the second set of two or more mathematical expressions is different from the first set of two or more mathematical expressions, the neighboring block includes a left block adjacent to the current block, and an intra prediction mode having no directionality includes a planar mode or a DC mode.