MSE of an image

[george_sp]

How can I calculate the Mean Square Error (MSE) of two RGB images (having 3 channels)? I am using the Opencv Library and it does not appear to have a function for this. Is there any formula? Please help..

[Lindley]

Are you assuming they're aligned, or are you using the MSE to try and align them? (There are better ways to align images, but MSE is a conceptually simple one.)

If the former, then pseudocode would be:

FOR every pixel
    FOR every channel
        ACCUMULATE the square difference in pixel channel intensity
DIVIDE by the number of pixels*channels

Using OpenCV, this may actually be easier if you convert your IplImage into a CvMat, because finding the squared difference of two matrices is very straightforward, as is accumulating an array. But the problem is trivial enough that a simple series of loops is probably about the same amount of code.