Optimal bit allocation for high-quality wavelet color image codec
Veyis Nuri, Ilyas Nuri · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1996
In this paper, a high quality, and in many prospects, efficient, wavelet color image codec (WCIC) is introduced. This codec allows to achieve high compression ratios with little degradation in visual quality. WCIC simultaneously exploits several characteristics of the wavelet transforms. Wavelet transform is formed using wavelet packets via lattice structures. Bit allocation algorithm is developed to distribute the bits between and in the colors such that minimal mean-squared-error is introduced in each color component. This proves to be beneficial at low bit rates which keeps the color distribution in balance. The wavelet coefficients are quantized using either trellis or zero-tree quantizers depending on their statistics. Quantized coefficients are further compressed with adaptive arithmetic coding resulting in the final coded bit stream. This codec is applied to a wide range of images, from computer animations to natural pictures. The results are compared to other algorithm, including fractals and JPEG, and relative merits of the proposed algorithm are presented.