> Note that a lovely reader informed me shortly after publication that indeed I can include my full domain name in a version 1 QR code by using all capital letters instead of lowercase. TIL that the "alphanumeric" character set for QR codes actually contains symbols for URLs like : and /.
This is a nice trick worth remembering. I have used it myself in the past. Handy not just for creating ultra small QR codes, but also for getting as much data as possible into the limits of the largest QR codes.
I saw similar engraved and then inked onto wooden boards at a restaurant, sadly, despite the error handling, 3 out of 4 I tried were not scannable, the 1 I did manage to scan to me to a reviews site for the restaurant (where a lot of reviews said they struggled to make the QR work - likely not the feedback the restaurant wanted)! I guess it kept me entertained whilst waiting for the bill.
I used something like this on a large sheet and cut it into pieces for a puzzle gift to a website where people left comments. Nowadays even easier to generate nice temporary websites for such things.
I’m picturing an acrylic version of it, or even some other fancier material.
The starter kit: a 21×21 board, with three 8×8 finder patterns, two 1×5 timing patterns, and 120 white and 119 black modules.
The Version 2 expansion pack includes a 25×25 board, two 1×4 timing patterns, one 5×5 alignment pattern, 76 white modules and 75 black modules.
And so on.
(I dunno about the desired ratio of individual black and white modules. I gather the general idea is to balance black and white, but does that include or exclude the fixed parts, where black is somewhat more common? Finder pattern is 33∶31 black∶white, alignment pattern is 17∶8, 1×5 timing pattern is 3∶2, 1×4 timing pattern is 2∶2.)
Then again, writing the url by hand and using OCR built into the camera app would probably be more practical and user friendly for everyone involved. Although for sure not as fun.
I found this page very helpful in understanding each step of the QR code creation process. I can't say I recall it all but it would be possible to turn this into a small booklet, I guess.
From the update: "Why are QR Codes with capital letters smaller than QR codes with lower-case letters?" https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capit... (https://news.ycombinator.com/item?id=43149077)
> (besides micro QR codes)
In case anyone else is interested: https://en.wikipedia.org/wiki/Rectangular_Micro_QR_Code
No, I don't think that's it! That's a "Rectangular Micro QR Code".
I think it's this: https://www.qrcode.com/en/codes/microqr.html
Rectangular Micro QR Codes are not ordinary Micro QR Codes.
this makes me wonder if there is an `infinite` version of QR Code that can be streamed from a printer (well, I guess things can be chunked).
> Note that a lovely reader informed me shortly after publication that indeed I can include my full domain name in a version 1 QR code by using all capital letters instead of lowercase. TIL that the "alphanumeric" character set for QR codes actually contains symbols for URLs like : and /.
This is a nice trick worth remembering. I have used it myself in the past. Handy not just for creating ultra small QR codes, but also for getting as much data as possible into the limits of the largest QR codes.
I saw similar engraved and then inked onto wooden boards at a restaurant, sadly, despite the error handling, 3 out of 4 I tried were not scannable, the 1 I did manage to scan to me to a reviews site for the restaurant (where a lot of reviews said they struggled to make the QR work - likely not the feedback the restaurant wanted)! I guess it kept me entertained whilst waiting for the bill.
I hand drew this on a whiteboard. It was a lot more work than I anticipated.
http://lars.nocrew.org/tmp/qr.png
By the way, I also coded a QR symbol generator in PDP-10 assembly language.
https://github.com/PDP-10/its/blob/master/src/lars/qrcode.8
I once sent a letter to a friend with a hand-written QR Code whose content was the typed letter.
It's cool for the receiver, but tedious for the sender (but it's a good way to help with difficult to read cursive).
If someone needs a gift idea:
I used something like this on a large sheet and cut it into pieces for a puzzle gift to a website where people left comments. Nowadays even easier to generate nice temporary websites for such things.
I’m picturing an acrylic version of it, or even some other fancier material.
The starter kit: a 21×21 board, with three 8×8 finder patterns, two 1×5 timing patterns, and 120 white and 119 black modules.
The Version 2 expansion pack includes a 25×25 board, two 1×4 timing patterns, one 5×5 alignment pattern, 76 white modules and 75 black modules.
And so on.
(I dunno about the desired ratio of individual black and white modules. I gather the general idea is to balance black and white, but does that include or exclude the fixed parts, where black is somewhat more common? Finder pattern is 33∶31 black∶white, alignment pattern is 17∶8, 1×5 timing pattern is 3∶2, 1×4 timing pattern is 2∶2.)
I remember retracing QR codes on graph paper to pass time in grade 12 physics, this was back in 2013/2014.
I've really enjoyed reading the Grid World piece linked at the bottom of the post: https://alex.miller.garden/grid-world/
Ah, I did just that this weekend.
Well... it wasn't QR-code but rather artoolkit markers. Let's just say I'll keep on printing them for a bit.
thats fun I would definitely scan this rather than a generated one
Then again, writing the url by hand and using OCR built into the camera app would probably be more practical and user friendly for everyone involved. Although for sure not as fun.
One time I tried to understand the QR algorithm and I didn't understand it at all despite trying multiple times.
Maybe I can try again with the help of LLMs. Hmm not a bad idea
I found this page very helpful in understanding each step of the QR code creation process. I can't say I recall it all but it would be possible to turn this into a small booklet, I guess.
https://typefully.com/DanHollick/qr-codes-T7tLlNi
Here's a HN discussion from 2022 about it.
https://news.ycombinator.com/item?id=32837565
Nice! I also found this page very helpful:
https://www.nayuki.io/page/creating-a-qr-code-step-by-step
This is an interactive guide that will break down the process for your specific QR-code.
That's the best explanation I've seen - thanks for sharing!
There is also a nice Veritasium video about it, if you prefer that: https://youtu.be/w5ebcowAJD8