MATLAB: Normalized Cross Correlation for rgb image

Image Processing Toolbox

Here is the code for to find normalized cross correlation between two images.
function NK = NormalizedCrossCorrelation(origImg, distImg)
origImg = double(origImg);
distImg = double(distImg);
NK = sum(sum(origImg .* distImg)) / sum(sum(origImg .* origImg));
But it works for grey scale images. When I run it for rgb image, error occurred: ??? Error using ==> mrdivide Inputs must be 2-D, or at least one input must be scalar.
Error in ==> NormalizedCrossCorrelation at 15 NK = sum(sum(origImg .* distImg)) / sum(sum(origImg .* origImg)); Can you please help me modify this code for rgb image. Thanks in advance.

Best Answer

See my attached demo of it.
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