Making a selection to match an image?

[aggsyb]

Ok I am still pretty new to c++ and have not used the Cimg lib but I am guessing it will be the easiest way to do this.

I was wondering how I can do the following.
If I have the hwnd of a program lets called it "Display image program", how can I scan a selection of the area inside of "Display image program" ? I basically want to have a database of images, and my program to search within a selected area of "Display image program" for those images in my database.

So in the bottom left of "Display image program" is an image that looks exactly like an X , this is the exact same image I have in my database pixel for pixel but I am only trying to scan the bottom left hand corner.

Any help greatly appreciated!