Dithered QR Codes (andrewt.net)

Coincidentally came across this after reading a comment [1] under the recent post on _for-sale DNS records, visiting milk.com and scrolling through the owner's Mastodon

[1] https://news.ycombinator.com/item?id=49224882

I recognize the domain name from playing some of his daily puzzles, namely Ronin and Cell Tower.

https://www.andrewt.net/puzzles/

This made me wonder if you could do it with color and apparently you can: https://1mentat.github.io/qr-code-shenanigans/

Nice writeup!

Only needs a Rick Astley QR code (;->

Is that Lena with Sean Connery’s face??

By the same author: https://mathstodon.xyz/@andrewt/115056697540191327

You can also run animations in QR codes: https://cgv.cs.nthu.edu.tw/Projects/Recreational_Graphics/Ha...

So, technically, you can run Doom inside a QR code?

I like the writing style. The first section is super clear about what QR code is in ~200 words

You can use colour as well: https://janglingpointer.github.io/Image_To_QR/

The guy that made that did a writeup on reddit: https://www.reddit.com/r/PixelArt/comments/1v52x96/

This reminds me of car safety features, how drivers have become more complacent to offset the benefits. QR codes were made to be robust in the face of errors, but over time this has been eaten into for aesthetic purposes. Businesses commonly put a logo in the center, eating up some error correction budget. This likely has a similar effect.

These are also very cool: https://antfu.me/posts/ai-qrcode

Diffusion image generation constrained to also be a valid QR code

I find it slightly disconcerting that lena has a mustache.

This is really neat!

A question I had about QR codes:

Let’s say I want to produce a QR code that is as close as possible to an image (let’s say the Nike swoosh logo), if I just added that to the center and added the 3 orientation markers on the corners it wouldn’t be a proper QR code yet, my question is what is the minimal amount of edits I would need to do from that symbol to get a valid QR code?

I’m thinking of something like people buying and hoarding domains in early 00’s (even now), if I could generate the minimal QR code (minimal is important here in the same way that .com is treated as superior to .ca or .net) of well-known symbols and buy the resulting domain it points to (if it even points to a domain) couldn’t I sell this to companies with the associated domain as a re-direct as well?

Greetings,

I could not find any LICENSE file or statement on the Codeberg repo. We must therefore conclude that the code is © Copyright 2025-2026, by the author(s), all rights reserved. Crazy to think there are already 3 forkers who've forked you.

Furthermore, let us not forget the patent-holder of QR Codes, DENSO WAVE, and their Frequently Asked Questions:

https://www.qrcode.com/en/faq.html

  Users of QR Code must be careful about deforming the code by overlaying it with an illustration or putting a a design on it. If it is deformed, the QR Code's error correction function is invoked where even a tiny missing or smeared part renders the reading operation impossible, or the response of the operation may become slow.
  If you are contemplating arranging an illustration or design involving a QR Code, please consult with DENSO WAVE about your project beforehand.

I'm not impressed.

the whole technique hinges on qr scanners reading only middle point of the squares

The moment you encounter developer that thought "for redundancy let's sample the whole square" (which is a very natural thought) - it breaks

I kinda expected working the limits of error correction, honestly. Not this blunt circumvention "because it works on my machine"

Pretty cool!

That’s very cool, but I’d be worried most regular people wouldn’t recognize it as a QR code and never scan it in the first place.

I think the first time I saw this was the Stable Diffusion controlnet that did the trick. Definitely an entertaining trick https://latentcat.com/en/blog/qrcode-controlnet

I played around with this a bit, first I did a photo of a cat I just took at a cat cafe, but the black and white cat didn’t turn out well with the dithering algorithm, so then I tried a selfie and pushing the radius up, it came out looking good, but then I tried aiming my iPhone camera at the screen and it didn’t see a QR code, only the face from the selfie. The ones on the main page, though, worked fine.

I always think of Russ Cox’s blog posts as canonical here: https://research.swtch.com/qart

Russ Cox’s QArt Codes[0] modifies how the URL is encoded to embed an image while keeping the QR code fully valid, without relying on error correction.

[0] https://research.swtch.com/qart

Related QArt discussions on HN: [1] https://news.ycombinator.com/item?id=15213044 (2017-09-10, 61 points, 6 comments) [2] https://news.ycombinator.com/item?id=3836935 (2012-04-13, 56 points, 9 comments) [3] https://news.ycombinator.com/item?id=8549772 (2014-11-03, 56 points, 4 comments)

You can alpha blend a QR code onto images easily and fit them into graphic designs

https://mastodon.social/@UP8/115939341268444811

https://mastodon.social/@UP8/113494337763505908 (R&D)

the two last one didn't scan at all on my phone :/

Once you understand how QR codes work it is more about "creativity" of what you want to do with your options! Next to shapes, contrast you can also use color and mix design approaches. https://qrocodile.io is a free tool that tries to push those limits of QR codes and keep it scanable and recreatable (vs. 1-time AI generated codes). It has a module based approach, so each module (pattern) can have a different approach on how to render a QR. I think a dithered QR code module is missing... something that could be added! :)

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