[devmandan]

A software tool should exist to repair QR codes. People could really benefit from it because QR codes are used everywhere.

I'd like to find a way to repair QR codes through software. However, that begins with collecting a bunch of broken and corrupted QR codes people stumble across and fixing them up by hand. This will help spot patterns in how they fail. So please help out by submitting your QR code that doesn't scan. Please don't create QR codes that don't scan just to submit them. Thank you! In the past I have fixed one QR code by hand and it is shown at the link.

[gblargg]

> A software tool should exist to repair QR codes.

Seems that the solution is to add more redundancy (and stop covering the center pixels with an icon). The codes are designed to be self-correcting if the damage is slight enough or more redundancy is added.

[Anonbrit]

If the problem is that the software can't find the centre, it could say so ,- that would hint to people that their icon is the problem

[stavros]

The problem isn't that it can't find the center, it's that you reduce redundancy by replacing those pixels with the icon. It can find the center fine and still be unable to scan because there isn't enough information there.

[fragmede]

but also because the link used has a bunch of tracking clumsily added, which further complicates scanning the thing. Compare the visual complexity of the QR code for HTTP://INSTAGRAM.COM/USERNAME (all caps is important*) vs the cutesy one the app generates.

* https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capit...

[stavros]

Yes, but that's more of a failing of the standard (a very natural usage pattern ends up being bad) vs what the user (or some app) did.

[fragmede]

I wanted to lampshade the caps part, but more explicitly, the QR code's Instagram link to my profile has igsh=xxxxxxxxxxxxx%3D%3D&utm_source=qr appened to it, where the X's are some tracking id. that tracking id that instafram app forces on people makes the qr code much more complicated (= smaller dots on a bigger qr code) which scans just fine on a iPhone 16 that instagram devs use, but that an 8 year old $50 Android phone isn't going to like as much.

[andylynch]

The bulk of the QR code is about specifying, quite exhaustively, multiple means of error prevention, detection , and correction. I guess some applications don’t use these features effectively, but compliant QR codes are really quite hard to corrupt.

[mdaniel]

> People could really benefit from it because QR codes are used everywhere.

I hear you, and at the same time we're solving the wrong end of that pipeline, in my opinion. Almost every QR code I have ever seen in my life either points to bit.ly or some other link-shortener or marketing tracker domain which I would put good money will be dead way before the QR code's ink deteriorates

I don't mean that QR is a terrible standard, but at least until we can get URL forms that are on the whole less than 128 characters, I wish they had met the world where it is. I believe the http2 compression scheme comes with dedicated dictionary slots for header strings that they know are going to appear, so QR would have benefited from the same (e.g. http/https taking less than 4/5 bytes, :// less than 3)

Then again, having thought further about this, I guess Marketing's Razor is the most likely explanation: it wasn't a technical reason they're using bit.ly, it's for those sweet engagement metrics

[simpaticoder]

I imagine that a really useful piece of information is where the QR code was spotted. So that means treating the photo of the QR code and its exif data as part of the puzzle. No doubt some URLs are more common in some parts of the world than others in a kind of ode to geoguessing games.