A new adaptive classified transform coding method [image coding]

An efficient discrete cosine transform technique using a new adaptive feature for bandwidth compression is described. Taking account of human visual characteristics and transform coefficient statistics, the higher activity region is further classified into four subclasses according to four proposed basic patterns, while the lower activity region is assigned to four subclasses according to its AC-energy (image activity) distribution. Computer simulations shows that the proposed adaptive coder exhibits a performance improvement of 1 dB or more over conventional adaptive coders at the same coding rates