Directional lifting wavelet and universal trellis coded quantization based image coding algorithm and objective quality evaluation

In this paper, an image coding algorithm based on directional lifting wavelet transform (DLWT) and universal trellis coded quantization (UTCQ) is presented, and the coding performance is evaluated with multi-scale structural similarity index (MSSIM) and peak signal-to-noise ratio (PSNR). Compared with discrete wavelet transform (DWT), DLWT can provide an efficient representation of edges, but shows a similar ability in representing the smooth area. In order to alleviate blurring artifacts in the smooth area, UTCQ is adopted to quantizing the wavelet coefficients. Experimental results show that the proposed algorithm has the best MSSIM performance among the compared algorithms (including JPEG2000), and its decoded images at low bit-rate are visually more appealing in both edges and smooth areas. The experimental results also show that UTCQ does perform better than scalar quantization (SQ) in MSSIM and improves the subjective visual quality, although it is not necessary better than SQ in PSNR.