I am looking for an open source program to recognise known features, letters, numbers and symbols, displayed on my screen on a 2D plane.
There may be some occlusion or particle effects over the images.
In this particular case I am trying to detect features from Hearthstone (an online card game).
The best answer will answer the question for a general case matching the features I am trying to identify as I want to develop with this and use it for other similar games.