A New Classified VQ Algorithm for Still Images in DCT Domain

정지 영상을 위한 DCT 영역에서의 분류화 벡터 양자화 방법

A new classified VQ scheme for DCT coefficients(DCT-CVQ) is proposed for still image coding. DCT coefficient matrices are classified into six classes by ac coefficients that well represent edge characteristics and the distribution of ac energy in the DCT domain. To reduce the complexity of, VQ, ac transform coefficients are partitioned into several vectors, and an adaptive method is provided by making different codebook sizes for different classes. Simulation results show that this DCT-CVQ results in good subjective quality at low bit rates, and SNR is increased by about 1.5-4.0 dB in the range 0.2-0.5 bpp, when compared with other DCT-VQ coding schemes.