i need an opencv code that will locate an image from multi-up images and then detect the differences between the original image and the detected similar image.

I am looking for someone to write an OpenCV/python code that will locate an image from a collection of multiple images and then detect the differences between the original image and the similar image located. The images will all be in the PNG file format, and the code should focus specifically on size differences rather than color variations or placement changes. I would prefer the code to be written using the Python programming language.