Variable region vector quantization, space warping and speech/Image compression

Algorithms for vector quantization of variable region data are given. The design iteration is proved to converge. An important issue here is the optimization step of the region shape with respect to the vector quantization codebook. Thus, the presented design method is a nontrivial extention of ordinary vector quantizer design which contains the classical Lloyd-Max algorithm. First, the main algorithm is given without introducing any physical entity. Therefore, the method is applicable to any data including speech and image as long as the quantization distortion is defined. In the speech coding case, which is the main body of this paper, the region shape optimization is interpreted as the epoch interval adjustment. The selection of the adjusted epochs with respect to the vector quantization codebook considerably reduces the quantizing distortion. This enables very-low-rate speech compression. Then, the image coding case is formulated and some convergence problem is discussed.