Context-based adaptive variable length coding for adaptive block transforms
AssigneeNokia Corporation
InventorsMarta Karczewicz, Justin Ridge
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Abstract
A method and system for coding an image using context-based adaptive VLC where transform coefficients are partitioned into blocks having a block dimension of 4n×4m (with n, m being positive integer equal to or greater than 1). Each block is scanned in a zigzag manner to produce an ordered vector of coefficients having a length of 16n×m. The ordered vector is sub-sampled in an interleaved manner to produce n×m sub-sampled sequences of transform coefficients prior to encoding the transform coefficients using an entropy encoder.
Claims16
A method of image coding using data indicative of an image, characterized by
- forming at least a block of transform coefficients from the image data, by
- scanning the block of transform coefficients for providing a sequence of transform coefficients, by
- sub-sampling the transform coefficients in the sequence in an interleaved manner for providing a plurality of sub-sampled sequences of transform coefficients, and by
- coding the sub-sampled sequences of transform coefficients using an entropy encoder.
A method of image coding using data indicative of an image, characterized by
- forming at least a block of transform coefficients from the image data, by
- scanning the block of transform coefficients for providing a sequence of transform coefficients, by
- coding the transform coefficients using an entropy encoder for providing a sequence of coded transform coefficients, and by
- sub-sampling the sequence of the coded transform coefficients in an interleaved manner for providing a plurality of sub-sampled sequences of coded transform coefficients.
A software product stored on a computer readable medium for use in image coding image data indicative of an image, wherein the coding process comprises the steps of:
- forming at least a block of transform coefficients from the image data, and
- scanning the block of transform coefficients for providing a sequence of transform coefficients, said software product characterized by
- an algorithm for sub-sampling the transform coefficients in the sequence in an interleaved manner for providing a plurality of sub-sampled sequences of transform coefficients.
An image encoder for receiving image data and providing a bitstream indicative of the image data, characterized by:
- means for forming at least a block of transform coefficients from the image data, by
- means for scanning the block of transform coefficients for forming an ordered sequence of transform coefficients from the block, by
- a software program stored on a computer readable medium for sub-sampling the ordered sequence of transform coefficients in order to form a plurality of sub-sampled sequences of transform coefficients, by
- means for entropy coding the sub-sampled sequences of transform coefficients for provided signals indicative of the encoded transform coefficients, and by
- means, for providing the bitstream based on the signals.
An image coding system comprising a server for providing a bitstream indicative of image data and a client for reconstructing the image data based on the bitstream, wherein the server characterized by
- a receiver for receiving signals indicative of the image data, by
- means for forming at least a block of transform coefficients from the signals, by
- means for scanning the block of transform coefficients for forming an ordered sequence of transform coefficients from the block, by
- a software program stored on a computer readable medium for sub-sampling the ordered sequence of transform coefficients in order to form a plurality of sub-sampled sequences of transform coefficients, by
- means for entropy coding the sub-sampled sequences of transform coefficients for provided further signals indicative of the encoded transform coefficients, and by
- means, for providing the bitstream based on the further signals.
A method of image coding using image data indicative of an image, characterized by
- forming at least a block of transform coefficients from the image data, by
- sub-sampling the transformation coefficients in the block in an interleaved manner for providing a plurality of sub-sampled blocks of transform coefficients, by
- scanning the sub-sampled blocks of transform coefficients for providing a plurality of sub-sampled sequences of transform coefficients, and by
- coding the sub-sampled sequences of transform coefficients using an entropy encoder.
A method of image coding using image data indicative of an image, wherein at least a block of transform coefficients is formed from the image data and the block of transformation coefficients is scanned for providing a sequence of transform coefficients located at a plurality of positions in the sequence, wherein the positions include a reference position so that each of said plurality of positions relative to the reference position defines a distance, said method characterized by
- assigning a cost value to each of the distances, by
- arranging the transform coefficients in the sequence into a plurality of sub-sequences based on the cost values, and by
- coding the sub-sequences of transform coefficients using an entropy encoder.
Dependencies are inferred from the claim text.