How can I detect / calculate if a small pictures is present inside a bigger picture?

Question

What I am trying to accomplish in PHP with GD or ImageMagick is the following:

I have one large image (say 2000 x 2000 pixels).. I would like to check if a second, s

Answer 1

Here is a good answer for C#: How to find one image inside of another?

While I'm pretty sure that it can be used for PHP too because it's just a generic algorithm it's quite bad idea to use PHP for image comparison.

Also refer to Wikipedia Template match article.