An adaptive DCT coding with edge based classification

Discrete cosine transform (DCT) coding has been proven to be an efficient means of image compression coding. A lot of effort has been made to improve the coding efficiency of DCT based coding. This paper presents an adaptive DCT coding based on edge information. This scheme is designed to properly exploit the correlation between edge direction and distribution of DCT coefficients. Edges are extracted from the original image first. Then sub-optimal block size and scanning order are determined at each block based on the extracted edges. This way an adaptive DCT scheme taking account of local characteristics of the image can be achieved. It is shown through simulations that the proposed algorithm outperforms a conventional coding scheme in terms of coding efficiency by about 15%.