| 摘要 |
PROBLEM TO BE SOLVED: To efficiently encode or decode a required component in an image by dividing the image into plural blocks, converting pixels of each block into coefficients of plural of frequency regions, obtaining a group of coefficients of a frequency region regarded as a same kind in different blocks and applying group unit coding to the group of the coefficients. SOLUTION: For example, assume an original digital image is divided into blocks each consisting of 8×8 pixels, and the blocks are fed to a 8×8 2-dimensional discrete cosine transform(DCT) device 200, which generates DCT coefficients for the 8×8 blocks. A quantizer Q201 quantizes each DCT coefficient. The quantized DCT coefficients are fed to a coefficient array 202, where the coefficients are rearranged in a hierarchical form. In this hierarchical form, the coefficients are grouped into plural sub bands. An encoder 203 encodes the sub bands of the coefficients into a bit stream which represents digital image. |
