The Moodstocks Android SDK by Moonstocks allows API interaction with the aim to implement image recognition features into an application. Classes include API searcher, configuration, scanner, and synchronizer.
You ever wonder how Google is able to figure out just what the heck you're talking about when you search for "blue album cover" and you're not talking about the first Weezer album? Google is able to use your previous search, as well as a plethora of other sources, to predict what it is you are most likely trying to find. Pretty cool stuff, once you get past how uncomfortable that may be.