An entropy based approach for SSIM speed up

This paper focuses on an entropy based formalism to speed up the evaluation of the Structural SIMilarity(SSIM) index in images affected by a global distortion. Looking at images as information sources, avisualdistortion typical setcan be defined for SSIM. This typical set consists of just a subset of information belongingto the original image and the corresponding one in the distorted version. As side effect, some general theoreticalcriteria for the computation of any full reference quality assessment measure can be given in order to maximizeits computational efficiency. Experimental results on various test images show that the proposed approachallows to estimate SSIM with a considerable speed up (about 200 times) and a small relative error (often lowerthan 5%)