[kupo]

Does the app produce a unique coded signal of flashing screen colours for each user? Otherwise, what's to stop someone from loading an image of their own face with someone else's barcode onto their smartphone and stealing sandwiches?

[thinkcomp]

The photo appears on the register (downloaded from our server each time you check out) in front of the cashier. The photo on the phone is just for aesthetics.

[drinian]

Can't wait to see that get abused.