I did this as a fun project a while back http://dittokey.com/ http://dittokey.com/ . I open sourced the app: https://github.com/andrewseddon/dittokey-iphone h

I did this as a fun project a while back http://dittokey.com/ http://dittokey.com/ . I open sourced the app: https://github.com/andrewseddon/dittokey-iphone https://github.com/andrewseddon/dittokey-iphone and computer vision: https://github.com/andrewseddon/keyify https://github.com/andrewseddon/keyify No production ready, complete hack, but it does work. The vision side is an interesting problem. This was a while back and i was dealing with older cameras. I should imagine with modern phone cameras it's a pretty simple problem.