First of all sorry for my english mistakes.

I am new to QT and got the next goal that has not yet found the way to do it:
Finding a pixmap within another pixmap , or QImage within QImage.
For you to better understand if and how the image was a pixmap of a window, and the other was the pixmap print the full desktop screen and then find the function in the desktop window and return the coordinates.

Any help will be very welcome, I need an idea of ​​where to seek this solution.
Thank you.