Performance improvement algorithms for colour image compression using DWT and multilevel block truncation coding

Abstract

This paper introduces two algorithms for colour image compression. The first one is intensity based adaptive quantization coding (IBAQC), while the second is a combination of discrete wavelet transforms (DWT) and the IBAQC algorithm. The AQC produced a good peak signal to noise ratio (PSNR) with high bit per pixels (bpp). The aim of this paper is to present algorithms with low bit rate whilst preserving the PSNR and image quality to an acceptable range. The experiments were performed using different kinds of standard color images, multi level quantizers, different thresholds, different block sizes, and different wavelet filters. Both algorithms considered the intensity variation of each colour plane. The results obtained showed a good reduction in bpp compared with the AQC algorithm, with a little loss in PSNR due to the dropping of some blocks that claimed to be low intensity variation according to a comparison with predefined thresholds for each colour plane.