I think it is pretty obvious that the OP is trying to build a program that reads a game in another application. Without considering whether or not the OP is attempting something legal or illegal, I'll just focus in generalities:

Image recognition as a general problem is UNSOLVED. This is why things like CAPTCHA and RECHAPTCHA work. Thus, nobody on this planet can give you a general solution, algorithm, or source code to recognize two images. Short of completing Nobel Prize-caliber research, the best you can do is seek a solution for your specific problem. Thus, if you want us to be able to give you advice, you have to post all details of your problem, including the images themselves (screenshots would be helpful), as well as what type of program you are trying to capture the image from.

Now then, given the grey area of your topic, if you choose to provide more detail, I strongly encourage you to explain in full why you are trying to perform this operation, because unless you have a very good reason, you will probably not get much help here.