METHOD AND APPARATUS FOR ENCODING AND DECODING IMAGE DATA, AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a method and apparatus for encoding/decoding image data with which compression efficiency of an image is increased while hardly degrading the image visibly.

SOLUTION: The image data encoding method includes: converting and quantizing pixel values of pixels in a block of image data (S14); determining a classification mode used to classify the conversion block into a first region having one or more coefficients other than 0 as coefficients of the conversion block and a second region having all coefficients of 0 as coefficients of the conversion block, based on a diagonal of the conversion block that is a block wherein the pixel values are converted and quantized (S16); and generating bit streams for the coefficients of the first region according to the determined classification mode and a first bit depth indicating a bit number required to binarize coefficients of the conversion block (S24).

COPYRIGHT: (C)2006,JPO&NCIPI