Image sequence coding using adaptive tree-structured vector quantisation with multipath searching

In the encoding of image sequences for transmission and storage, the coding algorithm must have the ability to adapt to changing image characteristics from sequence to sequence and from frame to frame. A new adaptive tree-structured vector quantisation (adaptive TSVQ) with multipath searching is described. The structure of the codebook tree is reorganised at an update interval, without requiring any transmission of side information. The 1-path tree searching algorithm is a simple method of finding the closest codeword in TSVQ. The disadvantage of 1-path searching is that the selected codewords are not, in general, closest to the input vectors. Hence, the multipath searching algorithm is proposed to improve the image quality. The improvement over the fixed TSVQ at the same bit rate is up to 2.54 dB when the number of the leaves in the codebook tree is 256 and 4-path searching is applied.<>