Variable-rate hierarchical vector quantization with variance classification

Because the bit rate can be adjusted depending on the network traffic situation, the variable bit rate is more suitable than a fixed rate for transmitting images on the network. In this paper, a new variable rate hierarchical classified vector quantization (VHCVQ) scheme is proposed. This technique is suitable for progressive transmission. In our two-stage VHCVQ scheme, we use the differences between the first-stage input vectors and the first-stage quantized vectors, called residual vectors, to code the image in the second stage. Usually the values between these differences are small and each is close to one another. Using the difference to code the image may reduce the codebook size and the bit rate as well. In our simulation, using these differences reduced the bit rate by about 0.075 bpp. © 2000 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 11, 138–143,