# US 12,192,487 B2 · Last coefficient coding for adaptive transform based video compression > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,192,487 B2 - Document ID: US12192487B2 - Status: Granted - Kind: B2 - Application number: 17/960,683 - Filed: 2022-10-05 - Published: 2023-02-09 - Granted: 2025-01-07 - Earliest claimed: 2016-07-15 - Assignees: InterDigital VC Holdings, Inc. - Applicants: Interdigital Vc Holdings, Inc. - Inventors: Sebastien Lasserre; Saurabh Puri; Patrick Le Callet - Web page: https://patentgrep.com/patent/US12192487B2 ## CPC - H04N 19/18: the unit being a set of transform coefficients - 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 19/13: Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] - 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 19/147: according to rate distortion criteria (rate-distortion as a criterion for motion estimation H04N19/567) - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/463: by compressing encoding parameters before transmission - H04N 19/60: using transform coding - H04N 19/91: Entropy coding, e.g. variable length coding [VLC] or arithmetic coding - H04N 19/192: the adaptation method, adaptation tool or adaptation type being iterative or recursive - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Coding of the last coded coefficient position is performed by basing the coding of the y coordinate of the position of the last coded coefficient on knowledge of the size of the partial transform used to generate a block of coefficients from a block of video pixels. This enables a context adaptive coding of the last coded coefficient parameter to be performed much more efficiently. ## Claims ### Claim 1 A method for encoding, comprising: applying a partial transform to a block of image values to obtain a block of transform coefficients; and entropy encoding the block of transform coefficients, wherein the entropy encoding of the block of transform coefficients comprises entropy encoding a syntax element representing a coordinate of a position of a last coded transform coefficient in the block of transform coefficients, the entropy encoding of the syntax element depending on a size of the partial transform. ### Claim 2 (depends on 1) The method of claim 1, wherein an information representative of the size of the partial transform is encoded in video data. ### Claim 3 (depends on 1) The method of claim 1, wherein the syntax element is a prefix resulting from a splitting of the coordinate of the position of the last coded transform coefficient in the block of transform coefficients into a prefix and a suffix, and wherein the entropy encoding further comprises inferring the value of the prefix from the size of the partial transform. ### Claim 4 (depends on 1) The method of claim 1, wherein an adaptive set of partial transforms that are learned offline is used to transform the block of image values. ### Claim 5 An apparatus for encoding comprising electronic circuitry configured to: apply a partial transform to a block of image values to obtain a block of transform coefficients; and entropy encode the block of transform coefficients, wherein the entropy encoding of the block of transform coefficients comprises entropy encoding a syntax element representing a coordinate of a position of a last coded transform coefficient in the block of transform coefficients, the entropy encoding of the syntax element depending on a size of the partial transform. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein an information representative of the size of the partial transform is encoded in video data. ### Claim 7 (depends on 5) The apparatus of claim 5, wherein the syntax element is a prefix resulting from a splitting of the coordinate of the position of the last coded transform coefficient in the block of transform coefficients into a prefix and a suffix, and wherein the entropy encoding further comprises inferring the value of the prefix from the size of the partial transform. ### Claim 8 A method for decoding, comprising: entropy decoding a block of transform coefficients obtained by applying a partial transform to an input block of image values, wherein the entropy decoding of the block of transform coefficients comprises entropy decoding a syntax element representing a coordinate of a position of a last coded transform coefficient in the block of transform coefficients, the entropy decoding of the syntax element depending on a size of the partial transform; and inverse transforming the block of transform coefficients using the partial transform to obtain an output block of image values. ### Claim 9 (depends on 8) The method of claim 8, wherein an information representative of the size of the partial transform is decoded from video data. ### Claim 10 (depends on 9) The method of claim 9, wherein the syntax element is a prefix resulting from a splitting of the coordinate of the position of the last coded transform coefficient in the block of transform coefficients into a prefix and a suffix, and wherein the entropy decoding further comprises inferring the value of the prefix from the size of the partial transform. ### Claim 11 An apparatus for decoding comprising electronic circuitry configured to: entropy decode a block of transform coefficients obtained by applying a partial transform to an input block of image values, wherein the entropy decoding of the block of transform coefficients comprises entropy decoding a syntax element representing a coordinate of a position of a last coded transform coefficient in the block of transform coefficients, the entropy decoding of the syntax element depending on a size of the partial transform; and inverse transform the block of transform coefficients using the partial transform to obtain an output block of image values. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein an information representative of the size of the partial transform is decoded from video data. ### Claim 13 (depends on 11) The apparatus of claim 11, wherein the syntax element is a prefix resulting from a splitting of the coordinate of the position of the last coded transform coefficient in the block of transform coefficients into a prefix and a suffix, and wherein the entropy decoding further comprises inferring the value of the prefix from the size of the partial transform. ### Claim 14 A non-transitory computer-readable storage medium storing program code instructions operative, when executed by a processor, to cause the processor to: apply an entropy decoding on a block of transform coefficients obtained by applying a partial transform to an input block of image values, wherein the entropy decoding of the block of transform coefficients comprises entropy decoding a syntax element representing a coordinate of a position of a last coded transform coefficient in the block of transform coefficients, the entropy decoding of the syntax element depending on a size of the partial transform; and inverse transform the block of transform coefficients using the partial transform to obtain an output block of image values. ### Claim 15 (depends on 14) The storage medium of claim 14, wherein an information representative of the size of the partial transform is decoded from video data. ### Claim 16 (depends on 14) The storage medium of claim 14, wherein the syntax element is a prefix resulting from a splitting of the coordinate of the position of the last coded transform coefficient in the block of transform coefficients into a prefix and a suffix, and wherein the entropy decoding further comprises inferring the value of the prefix from the size of the partial transform. ### Claim 17 A non-transitory computer-readable storage medium storing program code instructions operative, when executed by a processor, to cause the processor to: apply a partial transform to a block of image values to obtain a block of transform coefficients; and apply an entropy encoding to the block of transform coefficients, wherein the entropy encoding of the block of transform coefficients comprises entropy encoding a syntax element representing a coordinate of a position of a last coded transform coefficient in the block of transform coefficients, the entropy encoding of the syntax element depending on a size of the partial transform. ### Claim 18 (depends on 17) The storage medium of claim 17, wherein an information representative of the size of the partial transform is encoded in video data. ### Claim 19 (depends on 17) The storage medium of claim 17, wherein the syntax element is a prefix resulting from a splitting of the coordinate of the position of the last coded transform coefficient in the block of transform coefficients into a prefix and a suffix, and wherein the entropy encoding further comprises inferring the value of the prefix of the y coordinate from the size of the partial transform. ### Claim 20 (depends on 17) The storage medium of claim 17, wherein an adaptive set of partial transforms that are learned offline is used to transform the block of image values.