cross-correlation of 2 same sized images

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to cross-correlate same size images:

//FORWARD TRANSFORMS
cv::cuda::dft(image1, G_image1, Size(SIZE,SIZE), DFT_SCALE);        
cv::cuda::dft(image2, G_image2, Size(SIZE,SIZE), DFT_SCALE);        

//MULTIPLY CONJUGATE
cv::cuda::mulSpectrums(G_image1,G_image2,G_image1,true);    

//BACKWARD TRANSFORM
cv::cuda::dft(G_image1,RESULT,Size(SIZE,SIZE),DFT_REAL_OUTPUT | DFT_SCALE);

• result in unscaled cross-correlation
• to scale between (-1,1): normalize source images to have mean(src's) = 0, StdDev(src's) = 1 before computation