If you're considering having the OCR done by the Arduino, I suspect that's not practical. The Arduino has very little RAM and not much processing power, and OCR typically involves receiving and manipulating far more data than the Arduino can hold in RAM. Of course just about anything is possible if you throw enough effort and ingenuity at it, but to my mind the Arduino is not a sensible platform for doing OCR. You really need a microprocessor for that sort of thing, not just a microcontroller.