qr codes with human-readable sections are just that, really freakin visible. just like images with swastikas.. those that tolerate that crap will do so, those that abhor such things will report such nonsense to anyone they can. in case of accidental swastika, the rules still apply.

ie, still just an image

You could probably intentionally create a qr code with a simple recognizable symbol, but it’d still necessarily have “clutter” around it which would make it stand out less. Also there are hard limits on the length of contiguous horizontal or vertical “lines”.

there’s a mask process in qr code generation. the masks aims to try to make it look like uniform noise, so you don’t end up with blocks/lines of pure white or pure black. so you won’t end up with any recognizable symbol in the usual algorithmic generation

some more detail: it will use one of these patterns to invert some pixels until it finds one that results in more or less uniform noise.

it will also add a set of pixels in a designated mask identification zone that instructs the decoder which mask was used

<img alt="" src="https://lemmy.blahaj.zone/pictrs/image/e0c3d0a5-795d-4001-a187-e71f84eb3630.webp">

Do we upvote or downvote if we think its a stupid question how does this work?

Most likely if you wanted to generate qr code that looks like swastika, you would have to input very specific letter nonesense to do it. Its very specific scenario and just pointless waste of manhours to prevent it, when someone who would want to generate such qr code would just do something else if prevented.

Apparently there is a mechanism in the basic QR-code-generating algorithm that does something like this.

There are eight different patterns that can be used to display any given QR code's data. All eight versions get generated internally by the generation software and then they're assigned scores that penalize them based on various patterns:

• Large monochromatic blocks, anything more than 2x2 pixels of the same colour (white or black)
• Long lines of either colour
• Anything matching the "finder patterns" (the squares at the corners)
• Imbalance between 50% black and white pixels

The best one of the eight is the one that's actually printed.

So a swastika isn't explicitly searched for, but given that a swastika is composed of a bunch of long lines a QR code pattern like that would get penalized pretty harshly. The seven other QR codes would have to be even worse for it to slip through, and I bet the odds are pretty low for that.

Just wanted to say this is a fantastic question and the people who claim otherwise have bad reading comprehension

Short answer, the masks would prevent them most of the time because they’re there exactly to prevent large blocks of continuous color as that would be difficult to recognize. Can you have small swastikas or other stuff in the middle? Yeah, but I don’t think anyone matters much about that. You can also purposefully create one but it will be hard to be read by a scanner and it’s likely going to be more random noise than anything useful.

QR codes can have arbitrary looks even without dirty tricks (abusing the error correction to add a logo or taking advantage of central sampling to color all but the middle 3x3 square of each data pixel) but boy, is it hard.

Examples:
lemmy.sdf.org/post/31694735/18805217 (strings a long number in Number mode (3 decimal digits per 10 bits) to the URL, and somehow the resulting number turns out to be a small even number times a very high power of 2)
www.youtube.com/watch?v=qQkWjzqMbuA (uses padding bytes plus maybe some of that “intentional damage” in QR codes with logos)

Not a show, but The Martian, and soon Project Hail Mary