I am new to coding. I have one cad Image cad.png. And few images after 3D printing following the cad image print.png.

I want to compare cad image with the printed image to find whether it has printed accurately or not. What is the percentage of matching.
Later on, if possible try to predict whether it is overprinted or under printed.

images are of different sizes. Do i need any reference point to measure the object in the image.

how should i proceed?