Talking without math is sometimes meaningless. here is method that could be more reasonable and logical. More precise result might be give by Calculating the Structure similarity index(SSIM). This index has been proven to be more consistent with Human visual system (HVS). However, to do the math, one first need an image as "axiom", and Let A and N reconstruct the same image respectively. Matlab 2014a can do the math by calling the function, ssim(x,y), Where x can be set as the axiom acquired by some expensive camera,etc. and y can be re placed by the images re-generated by A or N.