Symmetrical image block scanning method for reducing block effect

Abstract

A scanning method for reducing block boundary effects in vector quantisation image coding by changing the scanning order to symmetrical ordering is disclosed. The method is based on a very simple symmetrical ordering between adjacent block boundaries and is applicable not only to two-dimensions but also to three-dimensions. The scanning of the invention is performed by dividing two-dimensional image into a number of small image blocks, thereafter the small image blocks are scanned as one-dimensional vector. The scanning order of each small image block arranged in the whole image is changed symmetrically in the directions of longitudinal and transversal axes so that the starting and ending points of image block may be identical.