Find known sub image in larger image

Question

Does anyone know of an algorithm (or search terms / descriptions) to locate a known image within a larger image?

e.g.

I have an image of a s

Answer 1

Here's the skeleton of code you'd want to use:

// look for all (x,y) positions where target appears in desktop
List findMatches(Image desktop, Image target, float threshold) {
  List locs;
  for (int y=0; y

You could consider other image distances (see a similar question). For your application, the RMS error is probably a good choice.

There are probably various Java libraries that compute this distance for you efficiently.