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Discussion on: A QR Code Primer

nataliedeweerd profile image
𝐍𝐚𝐭𝐚𝐥𝐢𝐞 𝐝𝐞 𝐖𝐞𝐞𝐫𝐝

They clearly look different even though they store the same content! What gives? I'm guessing these generators use different values for parameters like the QR Code version, error correction level, etc. That could explain why they look different. Is there a QR scanner that could show us this metadata? That's something I haven't looked into yet.

Correct! If you look at the two QR codes, you can spot some similarities between them. The first one is smaller (less accurate) than the second, which is a bit bigger (based on the size of the position marker squares top left, top right, and bottom left).

The higher the QR codes error correction, the more columns and rows that are added. Higher error correction does also increase the minimum printing size, as you don't want all of the columns & rows to smush together :) That's why, if you're in the UK, the NHS test & trace QR codes are huuuuge (nearly full A4 size) - they need a high level of accuracy, so they need to be printed bigger.

mebble profile image
Neil Syiemlieh Author

Wow that makes complete sense! So you're saying the NHS QR codes have so many rows and columns that the squares end up being pretty tiny. It would be great to be able to see this metadata.