I'm planning to get a QR code tattoo!

Leaning in *hard* on that cyberpunk aesthetic

I’m already a transhuman trans humanist transhumanist human, so I thought, “why not just go all the way and get a QR code tattoo?” This article is a compilation of basically all of the research I’ve done on this topic.

Now, I know what you’re thinking: “what happens if your tattoo goes to a broken link?” It happened to this unfortunate Argentinian football fan, after all.

However, unlike him, I have the foresight to link it to a domain I own instead of some random video on YouTube. Specifically, I’m linking it to a subdomain of my short domain, either q.aay.tw or qr.aay.tw. (I’ll still need to analyze which one produces the easiest-to-draw codes, so the specific link is still up in the air.)

Prior art

Some people on Reddit have already gotten QR tattoos, and their experiences provide the inspiration for mine.

u/bgrnbrg suggests a couple of things to make the tattoo more resillient:

  • Reducing the complexity to make it easier to draw, by using the smallest possible code (21x21 dots)
  • QR codes have built-in error correction, so you should crank up the error correction rate.
  • Drawing it on a flat surface, like the inner wrist, so it’s easier to scan.
  • Increasing the dot size to at least 1/8” squares, so a 21x21 code is a 2.75” square.
  • QR codes might end up having orphans, or individual white or black dots without any neighbors. These are liable to bleed over time, which can corrupt the code, so you should try to minimize those as much as possible by adjusting the mask.

Picking a QR code

Given all those constraints, we need some very fine-grained control over our QR generation. Most QR code generators are too simple, and don’t give enough control or output enough useful diagnostics about our generated code. However, there is one online generator that does give that fine control I need (and it’s a demo for a QR generator library, funnily enough). It’s been so useful, I’m actually thinking of using it to write a script that searches for an optimal QR code.

There are a couple of dials that I set on this generator:

  • Quartile error correction. High unfortunately requires at least 25x25 dots, so quartile is the best we’ve got.
  • Mask pattern. There are 8 possible masks that a QR code can have, and this is usually optimized to ensure scanners can see the QR code in the first place. In my case, however, I’m choosing this value to minimize orphaned dots. Unfortunately, some values still have a lot of orphans, even after you finagle with the mask pattern! That’s why I’m still deciding on the subdomain to encode.
QR masks, from Wikimedia, by Bobmath. Public domain.

What do I put there?

I have a couple of ideas:

  • A simple redirect to astrid.tech. Boring, but it works.
  • A vCard. It would be quite useful, especially when doing some professional networking.
  • Medical information, like my blood type, what medicines I’m taking, etc. Though, that would make it publicly available, which would kinda suck.
  • A link to this New York Times article that actually provides legitimate stats on why COVID vaccines aren’t actually that effective.
  • Inspired by this article by Nicolò Carpignoli, but with some modifications, I can additionally place an AR marker on my arm, and potentially do some extremely cool AR stuff with my body! (elaborated on later)

Naturally, being the greedy engineer that I am, I will choose all of the above.

A tattoo controller webservice!

I’ll link my QR code’s domain to a custom webservice, so I can link to any page of my choosing! I’ll also make an admin page so that I can control it from my phone! The vision is, I can literally just change the link seconds before someone else scans it, so they can see what I want them to see at that moment.

Obviously, since this is a public subdomain, the content will not be private, and it can be accessed by anyone with the link, whether or not they can see the QR code. Still, it will definitely provide something fun, and it will definitely be a conversation starter or party trick.

Augmented reality!?

I mentioned AR earlier. If you thought that QR stuff was a lot, AR is a whole ‘nother rabbit hole for me to go down.

There is a library by Carpignoli called AR.js, which provides AR tracking in JavaScript. That’s the library that he describes in the article mentioned above. It can track ARToolKit markers, with pregenerated markers here. The method described by Carpignoli’s article involves putting the AR marker over the QR code, but since my QR code is too small, I’ll simply put it to the side, something like this:

A large QR code next to a small AR marker

Technically, that makes it off-center now, but it wouldn’t be too hard to adjust the marker’s its offset in the AR library.

On the consideration list for the AR markers I’ll use:

  • Game of Life gliders (3x3_parity_6_5 numbers 2, 3, 4, 5, and possibly more)
  • Some of the easy-to-draw 3x3_hamming_6_3 ones to reduce risk of failure to scan
  • 3x3_parity_6_5/6 is a somewhat-aesthetic V
  • 3x3_parity_6_5/20 is symmetrical, I like symmetry
  • 3x3_parity_6_5 numbers 17 and 18 are F pentominoes
  • 3x3_parity_6_5/7 looks like a therefore sign
  • … more stuff? IDK

Temporary tattoos

I’m currently consulting a local tattoo artist about this, and I’m very certain that I’ll get it tattooed on me. But still, I’ll test it out with some temporary tattoos I ordered from from StickerYou. I want to test how well scanners can pick up the tattoos, and ensure that the locations I want them in are actually good locations to put them in.

StickerYou lets you customize a 8.5”x11” tattoo sheet with whatever tattoos you want for a $20 (incl. shipping) fee, and because I have a lot of different kinds of tattoos I want to test, they seemed to be the best deal around for what I want to do. Their UI was extremely laggy, buggy, and hard to use, and it took forever to make my tattoo sheet, but I did end up creating it:

The tattoo sheet I made.

It has the following objects on it:

TypeSizeQuantityNotes
QR: q.aay.tw1.5”3This looks around the size u/Odd-Care got his in.
QR: q.aay.tw2.0”4
QR: q.aay.tw2.7”3This is the size u/bgrnbrg got his in.
AR: 3x3_hamming_6_3/01.0”3
AR: 3x3_hamming_6_3/11.0”3
AR: 3x3_parity_6_5/61.0”3This is the one that Carpignoli’s AR playground uses by default, so it is easily tested.
AR: 3x3_parity_6_5/171.0”3It looks like a F pentomino!
AR: 3x3_parity_6_5/201.0”3It’s kinda aesthetic, ngl
AR: 3x3_parity_6_5/61.5”2If the 1” ones are too small, fallback to this size.
AR: 3x3_parity_6_5/62.0”2If 1.5” is too small, then god help me.

Anyway, this tattoo seems like it will be extremely cool! I’m quite hyped.

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