Wounded QR Codes • Hacker News Board

For those few of us that don't have any device with a built-in capability of interpreting QR codes: http://zxing.org/w/decode?u=http%3A%2F%2Fwww.datagenetics.co...

Re: Wounded QR Codes

#15

Post by ck2 » Fri, Nov 08, 2013, 5:34 PM UTC

For companies that make "creative" QR codes, aren't they already giving up the 20% error correction?

Re: Wounded QR Codes

#16

Post by Pxtl » Fri, Nov 08, 2013, 5:42 PM UTC

The bit at the end made me happy - I didn't know QR codes code be that large. I wonder what the practical maximum number of bits is? I just tried the ones on the Wikipedia page (http://en.wikipedia.org/wiki/QR_code#Storage) - the one that's 5 alignment blocks wide scans, but the one that's 7 alignment blocks wide does not. I assume my primitive old phone's camera lacks the resolution for it. Unfortunately the captions are wrong - they both say 177x177.

Re: Wounded QR Codes

#17

Post by dahart » Fri, Nov 08, 2013, 5:45 PM UTC

f2f wrote: post #2

literally prior art: http://research.swtch.com/qart and this one has the benefit of allowing you to make a qr code with your face on it :)

You can also embed higher-res images in QR codes without breaking them.

http://cgv.cs.nthu.edu.tw/Projects/Recreational_Graphics/Hal...

Re: Wounded QR Codes

#18

Post by nantes » Fri, Nov 08, 2013, 5:59 PM UTC

shawabawa3 wrote: post #10

riamu wrote: post #6

Wait... We're still talking about QR codes?

Whenever I read anything about QR codes I can't take it seriously because I always immediately think of this: http://picturesofpeoplescanningqrcodes.tumblr.com/

You know I do to, but usually only as I find myself actually scanning a QR code. Which is not all that rare it turns out, mostly bus stop schedules.

Re: Wounded QR Codes

#19

Post by aabalkan » Fri, Nov 08, 2013, 6:09 PM UTC

I managed to read most of the codes he marked as unreadable in QRReader iOS app. I don't know what he used. But kinda interesting article.

Re: Wounded QR Codes

#20

Post by jfoutz » Fri, Nov 08, 2013, 6:14 PM UTC

ck2 wrote: post #15

For companies that make "creative" QR codes, aren't they already giving up the 20% error correction?

Yes, but assuming errors are uniformly distributed, there's a chance read errors will actually correct problems. They'll occasionally flip the bit that was tampered with.

So error correction gets worse (less effective), but maybe not as bad as you might believe.