An adaptive transform approach for image compression

A new transform/subband coding algorithm is proposed. Its original characteristic is that the transform operator is continuously updated during the encoding process on the base of previously decoded samples. Unlike other content based algorithms, no data overhead is implied and the method can be easily incorporated into most image compression schemes. Simulation results demonstrate that a substantial benefit can be derived from the method in the context of still image and video compression. We describe and justify an adaptation algorithm for fixed size orthogonal transforms suitable for video compression, showing how it can be applied to a particular class of time-varying filter banks, thereby eliminating the specific drawbacks of transform coding, while retaining the advantages of continuous adaptation.