A Comparative Study Using LZW with Wavelet or DCT for Compressing Color Images

Abstract

As a result of the significance of image compression in reducing the volume of data, the requirement for this compression permanently necessary; therefore, will be transferred more quickly using the communication channels and kept in less space in memory. In this study, an efficient compression system is suggested; it depends on using transform coding (Discrete Cosine Transform or bi-orthogonal (tap-9/7) wavelet transform) and LZW compression technique. The suggested scheme was applied to color and gray models then the transform coding is applied to decompose each color and gray sub-band individually. The quantization process is performed followed by LZW coding to compress the images. The suggested system was applied on a set of seven standard images; the achieved compression results showed good efficiency in increasing the compression while keeping the fidelity level with the acceptable level. The acquired compression ratios are 20 for color Lena and 12.4 for gray Lena, both are 32 dB of PSNR.