This QR code is unreadable, why?

[frederikhors]

This is unreadable, why?

Thanks for you amazing work!

[realsimix]

I also have an image which can not be decoded:

[eventualbuddha]

The original image doesn't work with zbar either, but the second one does.

Shameless plug for https://zedbar.org/, my Rust port of zbar. No disrespect to rqrr! I use both it and zedbar in production since they can each decode some QR codes the other cannot.

[frederikhors]

@eventualbuddha why can't even the second one match the first photo?

[eventualbuddha]

@frederikhors good question! I did some investigation and found that the modules were too small to be counted reliably. Doing an upscale of the image fixed it in zedbar (eventualbuddha/zedbar#9), and I imagine a similar fix would work for rqrr.

The fix is part of zedbar v0.1.1 in both crates.io and npm. Try it out at https://zedbar.org/

(Sorry for the spam, @WanzenBug!)

[realsimix]

Shameless plug for https://zedbar.org/, my Rust port of zbar. No disrespect to rqrr! I use both it and zedbar in production since they can each decode some QR codes the other cannot.

Can zedbar be used from the shell somehow so it could replace zbarimg? I also like to use both.

[WanzenBug]

From this and similar issues in the past, it looks like jiggle_perspective, which should actually improve the acuracy of finding the exact alignment of pixels, does the opposite.

Most notably, when black and white patterns are only 1 pixel wide, it seems to screw up the calculation somehow. Leading to situations where you have a bit-perfect QR Code, orthogonally aligned as you would want it, and rqrr for some reason failing to detect it because the alignment gets screwed up 😓

I am currently quite busy, so I have yet to find the time to fix this issue. If some was to find and fix the issue, I would of course be grateful 😄

[eventualbuddha]

@realsimix yes, you can run cargo install zedbar and then use zedbarimg like you would use zbarimg.

@WanzenBug did you find that disabling jiggle_perspective fixes the OP image? Interesting if so 🤔

[realsimix]

For my picture above, I simply doubled its size in Gimp and afterwards qrtool was able to decode it.