Analysis of subband vector quantiser using colour spaces

In this paper, an analysis of the coding scheme for colour image compression, using different colour spaces along with subband vector quantisation is developed. This type of analysis is not done elsewhere. This technique offers the following advantages: (1) excellent edge reproduction, (2) no noticeable blockiness in the reproduced image, (3) very robust performance, and (4) the bit rates are less than 0.3 bpp. The major limitation of vector quantiser is blockiness at the edges. In the present work, analysis of the colour spaces (YIQ and HIS) along with subband vector quantisation is presented. Entropy versus variance curves for different colour spaces are drawn for different distributions of image gray levels. A systematic analysis of both colour spaces is presented. It is observed that the increased size of the code book gives a better reconstruction. However, a similar effect is shown to be obtained by using colour spaces, without increasing the size of the code book.