How are barcodes so fantastically easy to scan even when the surface is bend, warped or when scanned from an impossible angle?
In: Technology
[Here’s a nice video about barcodes](https://www.youtube.com/watch?v=XPuTZMp-HE8)
Important bits:
There are 9 bars that are always the same: the first 3, the middle 3, and the last 3. These bars can probably be used to help the computer correct for distortion.
Barcodes are asymmetric. The code for any number on the left side will always have an even number of white bars, while the the code for any number on the right will always have an odd number of white bars. So the computer can figure out of the barcode is upside down or not.
The last digit is always a check digit. The computer plugs in all the other numbers into a formula, and if the answer matches the last digit, then it knows it read the barcode correctly. Computers are suuuper fast, so it can reread the code many times really quickly. Even if it feels like it scanned immediately, it still might’ve taken a few tries.
I don’t think they actually are, the computers are likely doing all kinds of real time warp correction. Bars only come in a discrete number of sizes, so I’d think even a 1D array could estimate distortion and angles.
Many barcodes scanners are just cameras and those have all sorts of crazy computer vision business happening.
The bars are quite long, so unless the whole sticker is folded into itself then the machine can find a part where the bars are shown and can be identified.
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