Adaptive variable-length coding and decoding methods for image data
AssigneeSamsung Electronics Co., Ltd.
InventorsJae Moon Jo, Jechang Jeong
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Abstract
An adaptive variable-length coding/decoding method performs an optimal variable-length coding and decoding depending on an intra mode/inter mode condition, quantization step size and a current zigzag scanning position, such that a plurality of variable-length coding tables having different patterns of a regular region and an escape region according to statistical characteristics of the run level data are set. One of the variable-length coding tables is selected according to mode, quantization step size and scanning position, and the orthogonal transform coefficients according to the selected variable-length coding table are variable-length-coded.
Claims10
An adaptive variable-length coding method whereby quantized orthogonal transform coefficients are scanned in a zigzag pattern, are modified into run, level data and then are variable-length coded in a coding system for image data, said method comprising the steps of:
- setting a plurality of variable-length coding tables having different patterns of a regular region and an escape region according to statistical characteristics of said run, level data;
- selecting one of said plurality of variable-length coding tables according to intra/inter mode information of the currently processed block, zigzag scanning position and quantization step size;
- and
- variable-length coding the orthogonal transform coefficients according to said selected variable-length coding table, wherein said selecting step has the selecting range of a plurality of variable-length coding tables having different patterns of a regular region and an escape region according to said intra/inter mode information of the currently Processed block.
An adaptive variable-length decoding method for decoding image data encoded by an adaptive variable-length coding method, in which quantized orthogonal transform coefficients of the image data are scanned in a predetermined pattern and encoded, the decoding method comprising:
- selecting one of a plurality of variable-length decoding tables at least according to intra/inter mode information and scanning position, wherein the plurality of variable-length decoding tables comprise:
- a table selectable for an alternating-current (AC) component of an intra mode that is different from a table selectable for an inter mode;
- and
- a table selectable for a direct-current (DC) component of said intra mode, and
- the table for the DC component comprising variable-length codes further selectable according to the DC component that has been quantized by a quantization step size;
- and
- variable-length decoding the encoded quantized orthogonal transform coefficients according to the selected variable-length decoding table.
Dependencies are inferred from the claim text.