1. A method of processing an image, the method comprising: producing a test image; producing a test luminance image from the test image; producing a reference image; producing a reference luminance image from the reference image; producing a local mean luminance reference image as a convolution of the reference luminance image and a luminance filter function; producing a test contrast image in the absence of temporal filtering; producing a reference contrast image; producing a difference image; and producing a just noticeable difference image as a mathematical combination of the difference image, wherein the convolution is defined as confined convolution, which comprises: receiving an image; padding the image with zeros to provide a first intermediate image; convolving the first intermediate image with a selected non-negative kernel function to obtain a second intermediate image; cropping the second intermediate image to obtain a third intermediate image; receiving said third intermediate image, I 3 (x,y)=PCC{K(x,y),I(x,y)}; and forming a fourth intermediate image, defined as I 4 (x,y)=K(x,y c I(x,y)=PCC{K(x,y), I(x,y)}/PCC {K(x,y)/ΣxΣyK(x,y),I(x,y)}.