Creating barcodes readable off of the iPhone

The iPhone app I've created creates barcodes on the fly, that are scannable directly off of the iPhone. Creating the barcodes is relatively easy, figure out the encoding system you'll be using (these were Code 128 barcodes), the string of numbers you are encoding gets run through a function that creates start and end codes (that the scanner uses to verify it has correctly scanned the number). There are several true type fonts of barcode schemes available, and so you can just use the font to image tricks I've gone over before.

Because a piece of paper is reflective and the iPhone screen isn't, older barcode scanners will not work. They depend on the laser reflecting off of the paper and this won't work off of the iPhone (its screen transmits light, but doesn't really reflect it). I tried tweaking the colors of the coupon, but nothing helped. Fortunately most scanners are moving towards a system that is more like taking a digital image of the barcode (you can tell these because the laser doesn't just create a straight line on the coupon, it'll create a box, or something two dimensional). Since these scans are just looking at the image transmitted back, they'll work fine off of the iPhone (even when screen protectors are used).

Click here to see a sample