Chrominance Vector Quantization for Coding of Images and Video at Very Low Bitrates

Abstract

Vector quantization (VQ) is well-known as a powerful technique for image and video data compression. There are many practical possibilities to create vectors in an image. VQ, where vector components are the luminance's of some neighboring pixels, is often used. Another approach is to use the color coordinates of a pixel as the vector value which is then quantized. The chapter describes VQ in the two-dimensional space of the chrominance coordinates U and V. This VQ results in one scalar signal which is then processed independent of the luminance in any coder. The coder processes only one chrominance component instead of two. Proper ordering of the codebook decreases the frequency band of this scalar chrominance signal. The chapter also describes an efficient and non-iterative technique to generate the code book which is used to encode the chrominance pairs.