# US 2025/0159166 A1 · Image encoding and decoding apparatus, and image encoding and decoding method using contour mode based intra prediction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0159166 A1 - Document ID: US20250159166A1 - Status: Published application - Kind: A1 - Application number: 19/022,500 - Filed: 2025-01-15 - Published: 2025-05-15 - Earliest claimed: 2012-02-27 - Assignees: Dolby Laboratories Licensing Corporation - Applicants: Dolby Laboratories Licensing Corporation - Inventors: Jong Ki HAN; Chan Won SEO; Kwang Hyun CHOI - Web page: https://patentgrep.com/patent/US20250159166A1 ## CPC - H04N 19/124: Quantisation - H04L 45/745: Address table lookup; Address filtering - H04N 19/11: among a plurality of spatial predictive coding modes - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/12: Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264 - H04N 19/136: Incoming video signal characteristics or properties - H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/61: in combination with predictive coding - H04N 19/109: among a plurality of temporal predictive coding modes - H04N 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking - H04N 19/17: the unit being an image region, e.g. an object - H04N 19/179: the unit being a scene or a shot - H04N 19/597: specially adapted for multi-view video sequence encoding - H04N 19/82: involving filtering within a prediction loop - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract According to the present invention, an adaptive scheme is applied to an image encoding apparatus that includes an inter-predictor, an intra-predictor, a transformer, a quantizer, an inverse quantizer, and an inverse transformer, wherein input images are classified into two or more different categories, and two or more modules from among the inter-predictor, the intra-predictor, the transformer, the quantizer, and the inverse quantizer are implemented to perform respective operations in different schemes according to the category to which an input image belongs. Thus, the invention has the advantage of efficiently encoding an image without the loss of important information as compared to a conventional image encoding apparatus which adopts a packaged scheme. ## Claims ### Claim 1 A video decoding method performed by a video decoding apparatus, the method comprising: determining that intra skip coding is not applied to a current block; obtaining, at least partly based on the determination that the intra skip coding is not applied to the current block, information from a bitstream specifying that a contour mode based intra prediction is applied to the current block; deriving, at least partly in response to the information from the bitstream, a first depth value relating to the current block by performing the contour mode based intra prediction for the current block; deriving, based on the first depth value, a first index value using a first look up table specifying an index value corresponding to a depth value; deriving a second index value using the first index value and a residual index value, wherein the residual index value specifies a difference between the first index value and the second index value; and obtaining a second depth value relating to the current block based on the second index value and a second look up table specifying a depth value corresponding to an index value; generating a prediction block for the current block based on the second depth value; and reconstructing the current block based on the prediction block that is generated by the contour mode based intra prediction, wherein the first depth value is derived from a depth value of a neighboring pixel of the current block. ### Claim 2 (depends on 1) The method of claim 1, wherein the second index value is derived by adding the residual index value to the first index value. ### Claim 3 A video encoding method performed by a video encoding apparatus, the method comprising: determining that intra skip coding is not applied to a current block; determining, based on the determination that the intra skip coding is not applied to the current block, that a contour mode based intra prediction is to be applied to the current block; generating, based on the determination that the contour mode based intra prediction is to be applied to the current block, information specifying that the contour mode based intra prediction is performed for the current block; encoding the current block by performing the contour mode based intra prediction for the current block; and providing a bitstream that includes the encoded current block and the information specifying that the contour mode based intra prediction is performed for the current block, wherein the contour mode based intra prediction comprises: deriving a first depth value relating to the current block by performing the contour mode based intra prediction for the current block; deriving, based on the first depth value, a first index value using a first look up table specifying an index value corresponding to a depth value; deriving a second index value using the first index value and a residual index value, wherein the residual index value specifies a difference between the first index value and the second index value; obtaining a second depth value relating to the current block based on the second index value and a second look up table specifying a depth value corresponding to an index value; and generating a prediction block for the current block based on the second depth value, wherein the first depth value is derived from a depth value of a neighboring pixel of the current block. ### Claim 4 (depends on 3) The method of claim 3, wherein the second index value is derived by adding the residual index value to the first index value. ### Claim 5 A bitstream transmitting method for transmitting a bitstream which is generated by a video encoding method, the bitstream transmitting method comprising: generating the bitstream by encoding a video by the video encoding method; and transmitting the bitstream, wherein the video encoding method comprises: determining that intra skip coding is not applied to a current block; determining, based on the determination that the intra skip coding is not applied to the current block, that a contour mode based intra prediction is to be applied to the current block; generating, based on the determination that the contour mode based intra prediction is to be applied to the current block, information specifying that the contour mode based intra prediction is performed for the current block; encoding the current block by performing the contour mode based intra prediction for the current block; and providing a bitstream that includes the encoded current block and the information specifying that the contour mode based intra prediction is performed for the current block, wherein the contour mode based intra prediction comprises: deriving a first depth value relating to the current block by performing the contour mode based intra prediction for the current block; deriving, based on the first depth value, a first index value using a first look up table specifying an index value corresponding to a depth value; deriving a second index value using the first index value and a residual index value, wherein the residual index value specifies a difference between the first index value and the second index value; obtaining a second depth value relating to the current block based on the second index value and a second look up table specifying a depth value corresponding to an index value; and generating a prediction block for the current block based on the second depth value, wherein the first depth value is derived from a depth value of a neighboring pixel of the current block. ### Claim 6 (depends on 5) The bitstream transmitting method of claim 5, wherein the second index value is derived by adding the residual index value to the first index value.