Apparatus and method for image-compression encoding and decoding using adaptive transform

摘要

An apparatus and method for image-compression encoding and decoding using an adaptive transform in which, where different transform coefficients are outputted in accordance with a change of the transform direction order for an input image signal block, encoding and decoding procedures are conducted, based on the transform direction order selected in accordance with the characteristics of the input image signal block. In accordance with the present invention, an orthogonal transform and a inverse orthogonal transform for blocks are controlled, based on a determination made about whether signals within a block, to be currently encoded, have a higher correlation in a vertical direction or in a horizontal direction, using information about blocks encoded or both information about blocks encoded and information about the current block. In accordance with the present invention, the orthogonal transform is conducted in a direction associated with a higher correlation and then in a direction associated with a lower correlation. The inverse orthogonal transform is conducted in the order inverse to that of the orthogonal transform. Accordingly, the present invention provides an enhancement in compression coding efficiency.