QR error correction helps and hinders scanning

One thing that really annoys me with the use of qr codes (which are more often used due to the pandemic) is that many qr codes don't include the quiet zone required to scan the code. Instead they expect that the app the code is displayed in has a white background. But this doesn't work if you get a qr code via email and have dark mode active. In the first year of the pandemic I often had to fiddle with my mail app because of it, now I just have my app set to light mode. Generate correct QR codes, people!

On URL Versions: I find it odd that governments (eg Australia) that mandate QR codes to check-in to places have such complex information and detailed codes. This makes scanning the QR code more difficult due to the smaller dot size. This results in people huddling around a single point at a door for longer and closer proximity.<p>A little tech love such as using short URL’s with an intermediate backend that redirects to the complex site URL with a dozen query parameters would allow much lower resolution (lower version) QR codes that can be scanned faster and&#x2F;or from a further distance away resulting in better health outcomes. Or at least minimise the negative health outcome from the scanning process.

TLDR: Assuming a fixed qr code size, more resiliency to noise (mud on image, etc) requires putting more information in the code. To fit this the boxes need to be smaller, so that&#x27;s harder to read. But if you&#x27;re in a noisy environment and actually need the error correction it&#x27;s still worth it.

What I always hate is: at a bus stop I see a poster for, let&#x27;s say, a museum which includes a QR code to visit their site:<p><a href="https:&#x2F;&#x2F;i.imgur.com&#x2F;SHEmEPn.gif" rel="nofollow">https:&#x2F;&#x2F;i.imgur.com&#x2F;SHEmEPn.gif</a><p>I already know this is a URL with tracking parameters etc. As it encodes so much data and I am in a hurry, it takes my phone forever to scan.<p>Meanwhile, this QR code would have led me to their site as well:<p><a href="https:&#x2F;&#x2F;i.imgur.com&#x2F;IyxYyZN.gif" rel="nofollow">https:&#x2F;&#x2F;i.imgur.com&#x2F;IyxYyZN.gif</a>

Another interesting effect: If you have a version 1 code (the smallest size), there is no &quot;alignment&quot; block in the lower-right corner - only the main three positional blocks. Some scanning algorithms (such as the popular zxing library) struggle with this, and it actually works better to use a version 2 code.

What also makes scanning harder is people adding logos in the center &quot;using up&quot; some of the error correction.

The lowest level EC is the best for when you are building a QR code generator in Minecraft, trust me

Nice post, learned new things about QR codes. I noticed in the wild when doing check-ins, unreliable QR codes have been due to glossy paper and&#x2F;or their placement, either being too high or low causing distortion. <a href="https:&#x2F;&#x2F;datagenetics.com&#x2F;blog&#x2F;november12013&#x2F;index.html" rel="nofollow">https:&#x2F;&#x2F;datagenetics.com&#x2F;blog&#x2F;november12013&#x2F;index.html</a> illustrates the impact of different destruction cases<p>I&#x27;m surprised I haven&#x27;t seen NFC tags being used for covid check-ins as a secondary option to QR codes

Has someone made a QR code that is a random dot stereogram <i>and</i> which encodes something useful? Like the source code of the program which generates it or something. :)

Note that there are some areas that may not be damaged or the code is unreadable. The author avoided the big squares that are obvious to the eye and are required for positioning but there are also timing lines and metadata areas that are required for decoding.