Interleaved image adaptive vector quantization
Limin Wang, Morris Goldberg, Seymour Shlien · 1991
An image adaptive vector quantization technique is presented in the transform domain, where the codebook information is interleaved with the label information. The input image is first decomposed into a set of blocks. Then, each block undergoes a two-dimensional block discrete cosine transform (DCT). The DC coefficients are linearly quantized and encoded using a fixed-length code. The remaining AC coefficients are coded using adaptive vector quantization. The AC coefficients within blocks are combined into vectors from which a codebook is generated. In quantization, for each vector, the closest codeword is determined. If it is the first time the codeword is selected, the closest codeword is transmitted. Otherwise, the corresponding label is transmitted. To gain efficiency in transmitting the codewords, variable length coding (VLC) is used in encoding the codewords in the DCT domain. A reduction in bit rate required for transmitting the labels is accomplished by using a technique called codebook self-organization and by exploiting the correlation between the neighboring vectors.>