I am very happy to have tried your QRCode library and successfully recognised a photo of a version 1 QR code on screen, however there's a problem with higher resolutions and higher versions in photos.
Obviously a higher resolution lets you see more details so lets you have a more detailed QRCode on screen, but also it causes a dramatic increase in time and reduction in accuracy at finding the finder patterns, sometimes finding many many of them instead of just three.
I have found that there's a large increase in accuracy if I chop out the rest of the image, so maybe it needs to start with a very low resolution scan of the image to try to locate the code and only on those failing do progressively more accurate scans of the image just to locate the QRCode initially then ignore the rest?
Also would printing it in a specific bright colour increase accuracy at all - I haven't had a chance to look at the recognition algorithm yet but I'm guessing you could 'tag' the QRCode to improve recognition over just black.
QRCode from a photo at distance!