Variable length coding method and variable length decoding method

Abstract

An image coding apparatus provides a run-length encoding unit RLE 1 that subjects quantized coefficients which are obtained by quantizing frequency components of an image signal to a variable length coding process by using a run value Run that indicates the number of successive zero coefficients and a level value Lev that indicates a value of a non-zero coefficient following the zero coefficients. The run-length encoding unit RLE 1 includes a reordering unit Lreodr for reordering level values Lev; a variable length coder LVLC for coding reordered level values ROLev by using a code table that is selected according to the value of a quantization parameter QP; a reordering unit Rreodr for reordering run values Run from high frequency component of the quantized coefficients to low frequency component; and a variable length coder RVLC for coding reordered run values RORun by using a code table that is selected according to the number of already-processed run values. To execute a variable length coding process of quantized coefficients at high coding efficiency which are obtained by quantizing frequency components of image signals, while effectively removing redundant information contained in the quantized coefficients.

Description

[0001] This application is a divisional application of a patent application with the application number 02813282.3, the filing date being November 22, 2002, and the invention title being "Variable Length Coding Method and Variable Length Decoding Method". technical field [0002] The present invention relates to a variable length coding method and a variable length decoding method, and more particularly to a method for converting multiple data obtained by quantizing frequency components (quantization coefficients) of image data into coded data according to variable length coding processing. coefficients, and methods for decoding the encoded data to reconstruct coefficients according to a variable length decoding process. Background technique [0003] In recent years we have ushered in the multimedia age in which audio, video, and other data are processed integrally, and traditional information media such as newspapers, magazines, television, radio, and telephones (i.e., used ...

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Problems solved by technology

[0096] In addition, the decoding unit RLD0a of the conventional image decoding device 202a or the run-length decoding unit RLD0b or RLD0c of the conventional image decoding device 202b or 202c corresponds to a variable-length coding process for the quantization coefficient that cannot sufficiently remove the Coding unit of redundant information in the quantization coefficient

[0097] Also, for changing the variable length coding table (VLC table) according to the numerical value of the differential motion vector value when a variable length coding table is used to code a differential motion vector value in the method for predictively coding digital video data method, there is no effective change of the variable length coding table in the variable length coding process for data having a characteristic of the number of successive zero coefficients like quantized coefficients obtained by quantizing the frequency components of an image signal Methods

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