CZD (Czenakowski Distance) as PSNR is a per-pixel quality metric (it estimates the quality by measuring differences between pixels). Described in literature as being “useful for comparing vectors with strictly non-negative elements” it measures the similarity among different samples. This different approach has a better correlation with subjective quality assessment than PSNR. · R(i,j) are the pixels of the reference frame · I(i,j) are the pixels of the processed frame