Hybrid colour medical image compression by CDF wavelet and cosine transforms

In this research, we introduce an idea for Retinographic medical colour image compression, this new technique hybrid between Discrete Wavelet Transform (DWT) and Discrete Cosinus Transform (DCT). In recent times, developing hybrid schemes for effective image compression has gained enormous popularity among researchers. This research paper presents a proposed scheme for medical image compression based on hybrid compression technique (DWT and DCT). The goal is to achieve higher compression rates by applying different compression thresholds for the wavelet coefficients of each DWT band (LL and HH) while DCT transform is applied on LL bands with preserving the quality of reconstructed medical image. The retained coefficients are quantised by using adaptive quantisation according to the type of transformation. Finally the entropy coding (variable shift coding) is used to encode the quantisation indices. Experimental results show that the coding performance can be significantly improved by the hybrid DWT-DCT algorithm.