Improvement in Picture Evaluation Measure WSNR for Monochrome Still Picture Considering Local Entropy

Abstract

An objective evaluation measure AWSNR (Advanced Weighted Signal to Noise Ratio) which compensates coding noise by considering entropy in every 16×16 pixels sub-block is proposed. In order to clarify the relationship between MOS (Mean Opinion Score), SNR and entropy, a subjective evaluation test using twelve kinds of textures with ten different noise levels is carried out. After the noise compensation factor is experimentally derived from the entropy-SNR characteristics when MOS=4, 200 images with five kinds of coding noise or with random noise are evaluated subjectively and objectively. The results show an improved correlation coefficient with the MOS-AWSNR of 0.91, compared to 0.66 with the MOS-SNR.