FIG. 5.

Scatter plots, fitted lines, and correlation coefficient (CC) of average expert ranking of images versus similarity metrics (PSNR, SSIM, and MI). The highest correlation was observed between expert’s evaluation and MI. The PSNR showed the lowest correlation to expert’s perceptual ranking of images. The expert rankings suggest comparable perceptual resolution of all four image-based and wavelet-domain SRR methods and a marked improvement over original images resampled at higher resolution (a) CC=-0.776 (b) CC=-0.890 (c) CC=-0.943.