I am trying to solve two problems.

1. I have two same image one as it is and other as some rotation and shift in it. I tried using phase correlation for finding the shift on image and it works fine. But when there is rotation in image then because of that there is large pixel shift in corners of image and because of this I am getting wrong shifts by using phase correlation. I don't know how to find correct shift and rotation of image?? I tried using mellin transform but I found its implementation too tough in GitHub can someone give me simple implementation of that in C++.
2. In repeating structure also I am getting wrong answer using phase correlation. Can someone tell how to find location of maximum feature of image so that I can just compare that location and find correct shift of image in repeating structure.

Thank you