Overlapping block transform: window design, fast algorithm, and an image coding experiment

A window design and fast algorithm for the overlapping block transform (OBT) of size N×L are presented. The presented algorithm for the OBT reduces the calculation complexity to an N×N transform with a fast algorithm and a simple preprocessing including windowing. A signal-independent window optimization strategy is introduced for image coding application. Results for a first-order Markov model and an image coding experiment show, that the coding gains of the optimized OBTs increase and blocking effects decrease with increasing window length L. A comparison with DCT-coding shows that the OBT, which has a slightly increased realization complexity, provides higher coding gain and a significant blocking effect reduction