Codebook replenishment in classified pruned tree-structured vector quantization of image sequences

A fixed-rate image-sequence coding method has been designed for the transmission of television signals of broadcast quality over a 34 Mb/s channel. The codebook replenishment algorithm for classified pruned tree-structure vector quantization in the image-sequence coding method is discussed. Each field of the image sequence is processed as follows: it is first segmented into 4×4 blocks, which are classified and then cosine transformed; visual thresholds are applied to the resulting coefficients while the mean is quantized, coded, and sent separately. Quantization follows, using pruned tree-structured vector quantizers. The codebook replenishment algorithm then modifies the codebook trees according to the properties of the current field