Video signal encoding method and apparatus based on adaptive

Abstract

A method and apparatus encodes primary blocks included in an image signal based on the adaptive quantization technique. First, each primary block is divided into first subblocks of M.times.N data elements and second subblocks of P.times.Q data elements, wherein P and Q are multiples of M and N. A covariance for each first subblock is then calculated and compared with a threshold TH1 to thereby determine scalar blocks and primitive vector blocks, wherein a scalar block corresponds to a first subblock having a covariance greater than TH1 and a primitive vector block corresponds to a first subblock having a covariance not greater than TH1. Thereafter, a second subblock containing only primitive vector blocks therein is set as a candidate vector block and a covariance for the candidate vector block is calculated. Finally, primitive vector blocks not included in any of the candidate vector blocks or included in a candidate vector block having a covariance not smaller than TH2 are determined as first vector blocks; and candidate vector blocks having covariances smaller than TH2 are determined as second vector blocks. Thereafter, the scalarblock is scalar-quantized to thereby generate scalar quantized data, and the first and second vector blocks are vector-quantized on a first vector block and a second vector block bases to thereby provide first and second vector quantized data, respectively.