📅 Original date posted:2023-02-19
🗒️ Summary of this message: Using only upper case letters and numbers in codex32 and avoiding most punctuation can significantly reduce the size of QR codes.
📝 Original message:An easy but possibly very important tip:
If you use only UPPER CASE alpha and numbers in codex32, and avoid most
punctuation, it makes QR rendering of it significantly smaller. This is
because the QR code to the ISO SPEC, when seeing lowercase, assumes the
value is binary, then converts it to a two byte value. If instead, the
codex32 is all upper, and it uses only the 45 allowed characters (see
https://www.thonky.com/qr-code-tutorial/alphanumeric-table) , it will leave
it single byte and try to compress it. Of course it doesn’t compress well,
but that is OK because it at least didn’t double the size first.
See our research on this topic at
https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-003-uri-binary-compatibility.md
A superior QR codec can do better (see our
https://github.com/BlockchainCommons/QRCodeGenerator or
https://www.nayuki.io/page/qr-code-generator-library) but many platforms
and more basic QR codecs will double the size of the QR if you have any
lower case.
— Christopher Allen
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Christopher Allen [ARCHIVE] /
npub19g…ct5d0
2023-06-07 23:19:43
in reply to nevent1q…6prn
Author Public Key
npub19g47w5ewcqlpd7n07wpkp5cvcu2gjwrse0vl47l0avwl9hu933xsqct5d0Published at
2023-06-07 23:19:43Event JSON
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"content": "📅 Original date posted:2023-02-19\n🗒️ Summary of this message: Using only upper case letters and numbers in codex32 and avoiding most punctuation can significantly reduce the size of QR codes.\n📝 Original message:An easy but possibly very important tip:\n\nIf you use only UPPER CASE alpha and numbers in codex32, and avoid most\npunctuation, it makes QR rendering of it significantly smaller. This is\nbecause the QR code to the ISO SPEC, when seeing lowercase, assumes the\nvalue is binary, then converts it to a two byte value. If instead, the\ncodex32 is all upper, and it uses only the 45 allowed characters (see\nhttps://www.thonky.com/qr-code-tutorial/alphanumeric-table) , it will leave\nit single byte and try to compress it. Of course it doesn’t compress well,\nbut that is OK because it at least didn’t double the size first.\n\nSee our research on this topic at\nhttps://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-003-uri-binary-compatibility.md\n\nA superior QR codec can do better (see our\nhttps://github.com/BlockchainCommons/QRCodeGenerator or\nhttps://www.nayuki.io/page/qr-code-generator-library) but many platforms\nand more basic QR codecs will double the size of the QR if you have any\nlower case.\n\n— Christopher Allen\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20230219/34d9d295/attachment.html\u003e",
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