A very sophisticated set of image processing and computer vision algorithms extracts the 16-digit code from the iTunes Card and converts it into a string in few milliseconds. Core Animation, Accelerate, Core Graphics, GCD, AVFoundation and other frameworks were combined together to meet some very strict performance and usability requirements.
When you present the redeem code to the camera, the surrounding rectangle of the code is immediately localized within the camera scene and highlighted with a white rectangle. If you move the card in front of the camera, this white rectangle follows the card movements. After few milliseconds, the redeem code is converted in a string and then, of course, in money credit, so you can buy songs or apps.
Interestingly, the camera Code Redeemer can also be used by the blind. VoiceOver is utilized to help the user position the card in front of the camera.
More information at the link below...
Read More [via CultofMac]