social.coop

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Calishat<a href="https://researchbuzz.masto.host/tags/DOOM" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#DOOM</a> <a href="https://researchbuzz.masto.host/tags/VideoGames" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#VideoGames</a> <a href="https://researchbuzz.masto.host/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a> <a href="https://researchbuzz.masto.host/tags/stunting" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#stunting</a> <a href="https://researchbuzz.masto.host/tags/lmao" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#lmao</a> 'Backdooms is a Doom-like game that fits inside a QR code. That's to say, the code of the game is so concise that it can be represented by a legit QR code, which offers a maximum of 3 kilobytes of data.'<a href="https://boingboing.net/2025/04/18/doom-in-a-qr-code.html" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://boingboing.net/2025/04/18/doom-in-a-qr-code.html</a>

Anne DelongAs this article illustrates, you can't tell where a QR code will lead when you read it with your phone. It's important to have a QR code reader that lets you look at the actual website URL before you decide to visit, not one that takes you there automatically.<a href="https://www.peninsulanewsreview.com/news/flyers-with-qr-code-raise-eyebrows-in-ladysmith-7952440?utm_source=flipboard&utm_medium=activitypub" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.peninsulanewsreview.com/news/flyers-with-qr-code-raise-eyebrows-in-ladysmith-7952440?utm_source=flipboard&utm_medium=activitypub</a><a href="https://musician.social/tags/QRcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRcodes</a> <a href="https://musician.social/tags/websites" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#websites</a> <a href="https://musician.social/tags/security" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#security</a>

sebsauvage<a href="https://framapiaf.org/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a> Comme l'outils "Camera" de Windows 10 est tout pourri et qu'il met 3 plombes à décoder un QR-Code, est-ce que vous auriez une page qui permette de faire ça avec la webcam ?J'ai trouvé ça : <a href="https://scanapp.org/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://scanapp.org/</a> mais c'est pas encore super-réactif.EDIT: Ah j'avais oublié LHV: <a href="https://lehollandaisvolant.net/tout/tools/rqrcode/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://lehollandaisvolant.net/tout/tools/rqrcode/</a> (<a href="https://github.com/mebjas/html5-qrcode" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://github.com/mebjas/html5-qrcode</a>) Simple, efficace, rapide.

Detlev Zundel<a href="https://hostsharing.coop/tags/TIL" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#TIL</a> <a href="https://hostsharing.coop/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a> can look different but encode the same payload.<a href="https://qrplanet.com/help/article/why-two-qr-codes-with-the-same-url-can-look-different" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://qrplanet.com/help/article/why-two-qr-codes-with-the-same-url-can-look-different</a>Reading the explanation, this seems obvious, but somehow I was amazed that a QR Code generated from the command line (without any extra switches) and from an encoder on the web looked pretty different.

Flippin' 'eck, Tucker!<a href="https://mastodon.social/@glynmoody" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@glynmoody</a> Like so many things it's not really the technology that's at fault. QR codes are a convenient way of encoding & transmitting information.The problems are that (a) most phones are configured to automatically load the webpage pointed at by a QR Code (assuming it encodes a URL) and (b) the persistent problem behind almost all online scams -- users are not given the tools or knowledge to help them detect a fraud.I use <a href="https://secuso.aifb.kit.edu/english/" rel="nofollow noopener noreferrer" target="_blank">the SECUSO QR Scanner app</a> on my phone which not only displays the URL before launching it, but requires the user to check a confirmation box forcing you to think a bit more about what's about to happen.Of course that only solves problem (a) above.<a href="https://social.chatty.monster/tags/QRcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRcodes</a>

Glyn MoodyQR code '<a href="https://mastodon.social/tags/quishing" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#quishing</a>' scams up 14-fold in five years - <a href="https://www.bbc.com/news/articles/cq6yznmv3gzo" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.bbc.com/news/articles/cq6yznmv3gzo</a> this is why I hate <a href="https://mastodon.social/tags/QRcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRcodes</a>, and avoid using them...

Andy<a href="https://mastodon.scot/tags/Fraud" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Fraud</a> <a href="https://mastodon.scot/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a> <a href="https://mastodon.scot/tags/Parking" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Parking</a> <a href="https://mastodon.scot/tags/Scam" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Scam</a> <a href="https://mastodon.scot/tags/Fraudulent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Fraudulent</a> <a href="https://mastodon.scot/tags/Scams" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Scams</a> <a href="https://mastodon.scot/tags/ScamsAndFraud" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#ScamsAndFraud</a> <a href="https://mastodon.scot/tags/Technology" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Technology</a> <a href="https://mastodon.scot/tags/SmartPhones" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#SmartPhones</a> <a href="https://mastodon.scot/tags/quishing" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#quishing</a> <a href="https://mastodon.scot/tags/quishingScam" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#quishingScam</a> <a href="https://mastodon.scot/tags/QRCodeFraud" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodeFraud</a> <a href="https://mastodon.scot/tags/Cyber" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Cyber</a> <a href="https://mastodon.scot/tags/CyberSecurity" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CyberSecurity</a> <a href="https://mastodon.scot/tags/cybersecuritynews" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#cybersecuritynews</a> Always worth a post when so many scams are out there. Beware QR codes!!!Organised gangs behind rise in QR 'quishing' scams <a href="https://www.bbc.com/news/articles/cq6yznmv3gzo" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.bbc.com/news/articles/cq6yznmv3gzo</a>

William DentonToday's pleasant discovery: If you search DuckDuckGo for qr code the text you want in a QR codethen it generates the QR code for you. This is going to make things much easier with the ebooks I'm including in my book display in the library.<a href="https://cosocial.ca/tags/QRcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRcodes</a>

Andrii Mishkovskyi 🇺🇦QR codes? QR codes! <a href="https://hachyderm.io/tags/qrcode" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qrcode</a> <a href="https://hachyderm.io/tags/qrcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qrcodes</a> <a href="https://hachyderm.io/tags/kewahrcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#kewahrcodes</a> <a href="https://hachyderm.io/tags/kubecon" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#kubecon</a> <a href="https://hachyderm.io/tags/qrcon" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qrcon</a>

Montalvo<a href="https://mstdn.mx/tags/ios" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#ios</a> Compartir textos de manera sencilla y protegida, usando solo <a href="https://mstdn.mx/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a>? Te recomiendo muchísimo esta aplicación: <a href="https://papervault.eu" rel="nofollow noopener noreferrer" target="_blank">https://papervault.eu</a>

AI6YR BenApparently someone is sticking fake "Parking Payment" QR codes on parking meters in Manhattan Beach (California). <a href="https://m.ai6yr.org/tags/qrcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qrcodes</a> <a href="https://m.ai6yr.org/tags/scam" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#scam</a> 2025-04-01 13:26:52 PDTThe City warns residents and visitors about a scam involving unauthorized QR codes for parking payments. Currently, there are no QR codes for online payments at parking meters or pay stations.Please avoid using any QR codes you come across, as they may lead to fraudulent sites. Only use official payment methods.Report any suspicious activity to our Police Department. Stay safe and vigilant!If you see a QR Code on a parking meter, do not scan it. Contact Manhattan Beach Police at (310) 545-4566.<a href="https://member.everbridge.net/311578402488335/notif/YuHHaxdfx" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://member.everbridge.net/311578402488335/notif/YuHHaxdfx</a>

Erik van Straten<a href="https://mastodon.nl/@rooskatoen" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@rooskatoen</a> : not intended to offend, but to teach:Type: https:⧸⧸wikipedia.org in the address bar of your browser, or make sure that something like "warn for http" or "always use https" is enabled in the browser settings (on iOS/iPadOS Safari and Chrome support it, AFAIK Edge on no platform at all).Doing that prevents (albeit not very common) attacks like described in <a href="https://www.bleepingcomputer.com/news/security/australian-charged-for-evil-twin-wifi-attack-on-plane/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.bleepingcomputer.com/news/security/australian-charged-for-evil-twin-wifi-attack-on-plane/</a>.If tooting, type what I wrote, or https:⧸⧸www.wikipedia.org (or perhaps https:⧸⧸en.wikipedia.org if you prefer English).Note: I typed https:⧸⧸ instead of https:// because if I'd used the latter, Mastodon would have shortened the link and hidden the protocol, like in <a href="https://en.wikipedia.org/wiki/List_of_most-visited_websites" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://en.wikipedia.org/wiki/List_of_most-visited_websites</a>.Enjoy learning ICT, and don't use third party (privacy invasive D-tour) URL shortening services, and neither third party QR-code generators!<a href="https://mstdn.social/@Microplastics101" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@Microplastics101</a> <a href="https://indieweb.social/@jbz" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@jbz</a> <a href="https://infosec.exchange/tags/URLShorteners" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#URLShorteners</a> <a href="https://infosec.exchange/tags/QRcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRcodes</a>

Erik van Straten<a href="https://mastodon.social/@andrethemac" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@andrethemac</a> : dank voor de tip! Ga ik naar kijken.Uit <a href="https://secuso.aifb.kit.edu/english/105.php" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://secuso.aifb.kit.edu/english/105.php</a> gebruik ik zelf <a href="https://play.google.com/store/apps/details?id=com.secuso.privacyFriendlyCodeScanner" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://play.google.com/store/apps/details?id=com.secuso.privacyFriendlyCodeScanner</a>.<a href="https://mastodon.nl/@ErikSchouten73" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@ErikSchouten73</a> <a href="https://infosec.exchange/tags/SECUSO" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#SECUSO</a> <a href="https://infosec.exchange/tags/PrivacyFriendlyApps" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#PrivacyFriendlyApps</a> <a href="https://infosec.exchange/tags/InfoSec" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#InfoSec</a> <a href="https://infosec.exchange/tags/QR" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QR</a> <a href="https://infosec.exchange/tags/QRcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRcodes</a> <a href="https://infosec.exchange/tags/QRScanner" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRScanner</a> <a href="https://infosec.exchange/tags/BarCodeScanner" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#BarCodeScanner</a> <a href="https://infosec.exchange/tags/QRGenerator" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRGenerator</a> <a href="https://infosec.exchange/tags/QRCodeGenerator" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodeGenerator</a>

Terence Eden’s BlogA Recursive QR Code<a href="https://shkspr.mobi/blog/2025/03/a-recursive-qr-code/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://shkspr.mobi/blog/2025/03/a-recursive-qr-code/</a>I've been thinking about fun little artistic things to do with QR codes. What if each individual pixel were a QR code?There's two fundamental problems with that idea. Firstly, a QR code needs whitespace around it in order to be scanned properly.So I focussed on the top left positional marker. There's plenty of whitespace there.Secondly, because QR codes contain a lot of white pixels inside them, scaling down the code usually results in a grey square - which is unlikely to be recognised as a black pixel when scanning.So I cheated! I made the smaller code transparent and gradually increased its opacity as it grows larger.I took a Version 2 QR code - which is 25px wide. With a 2px whitespace border around it, that makes 29px * 29px.Blow it up to 2900px * 2900px. That will be the base image.Take the original 25px code and blow it up to the size of the new marker, 300px * 300px. Place it on a new transparent canvas the size of the base image, and place it where the marker is - 400px from the top and left.Next step is creating the image sequence for zooming in. The aim is to move in to the target area, then directly zoom in.The whole code, if you want to build one yourself, is:<pre><code>#!/bin/bash# Input fileinput="25.png"# Add a whitespace borderconvert "$input" -bordercolor white -border 2 29.png# Upscaled image sizeupscaled_size=2900# Scale it up for the baseconvert 29.png -scale "${upscaled_size}x${upscaled_size}"\! base.png# Create the overlayconvert -size "${upscaled_size}x${upscaled_size}" xc:none canvas.pngconvert "$input" -scale 300x300\! 300.pngconvert canvas.png 300.png -geometry +400+400 -composite overlay.png# Start crop size (full image) and end crop size (target region)start_crop=$upscaled_sizeend_crop=350# Zoom-in target position (top-left corner)target_x=375target_y=375# Start with a completely opaque imageoriginal_opacity=0# Number of intermediate imagessteps=100for i in $(seq 0 $((steps - 1))); do # Calculate current crop size crop_size=$(echo "$start_crop - ($start_crop - $end_crop) * $i / ($steps - 1)" | bc) crop_size=$(printf "%.0f" "$crop_size") # Round to nearest integer # Keep zoom centered on the target crop_x_offset=$(echo "$target_x - ($crop_size - $end_crop) / 2" | bc) crop_y_offset=$(echo "$target_y - ($crop_size - $end_crop) / 2" | bc) # Once centred, zoom in normally if (( crop_x_offset < 0 )); then crop_x_offset=0; fi if (( crop_y_offset < 0 )); then crop_y_offset=0; fi # Generate output filenames background_file=$(printf "%s_%03d.png" "background" "$i") overlay_file=$(printf "%s_%03d.png" "overlay" "$i") combined_file=$(printf "%s_%03d.png" "combined" "$i") # Crop and resize the base convert "base.png" -crop "${crop_size}x${crop_size}+${crop_x_offset}+${crop_y_offset}" \ -resize "${upscaled_size}x${upscaled_size}" \ "$background_file" # Transparancy for the overlay opacity=$(echo "$original_opacity + 0.01 * $i" | bc) # Crop and resize the overlay convert "overlay.png" -alpha on -channel A -evaluate multiply "$opacity" \ -crop "${crop_size}x${crop_size}+${crop_x_offset}+${crop_y_offset}" \ -resize "${upscaled_size}x${upscaled_size}" \ "$overlay_file" # Combine the two files convert "$background_file" "$overlay_file" -composite "$combined_file"done# Create a 25fps video, scaled to 1024pxffmpeg -framerate 25 -i combined_%03d.png -vf "scale=1024:1024" -c:v libx264 -crf 18 -preset slow -pix_fmt yuv420p recursive.mp4</code></pre><a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://shkspr.mobi/blog/tag/art/" target="_blank">#art</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://shkspr.mobi/blog/tag/qr/" target="_blank">#qr</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://shkspr.mobi/blog/tag/qr-codes/" target="_blank">#QRCodes</a>

Terence Eden🆕 blog! “A Recursive QR Code”I've been thinking about fun little artistic things to do with QR codes. What if each individual pixel were a QR code?There's two fundamental problems with that idea. Firstly, a QR code needs whitespace around it in order to be scanned properly.So I focussed on the top left positional marker. There's plenty of whitespace there.Secondly, because QR codes…👀 Read more: <a href="https://shkspr.mobi/blog/2025/03/a-recursive-qr-code/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://shkspr.mobi/blog/2025/03/a-recursive-qr-code/</a> ⸻ <a href="https://mastodon.social/tags/art" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#art</a> <a href="https://mastodon.social/tags/qr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qr</a> <a href="https://mastodon.social/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a>

Absolute Memery 🎭<a href="https://tribe.net/tags/RickRoll" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#RickRoll</a> <a href="https://tribe.net/tags/RickRolled" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#RickRolled</a> <a href="https://tribe.net/tags/RickAstley" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#RickAstley</a> <a href="https://tribe.net/tags/NeverGonnaGiveYouUp" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#NeverGonnaGiveYouUp</a> <a href="https://tribe.net/tags/QR" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QR</a> <a href="https://tribe.net/tags/QRCode" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCode</a> <a href="https://tribe.net/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a>.<a href="https://tribe.net/tags/Meme" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Meme</a> <a href="https://tribe.net/tags/Memes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Memes</a> <a href="https://tribe.net/tags/Humour" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Humour</a> <a href="https://tribe.net/tags/Humor" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Humor</a>

Elyse M GrassoI have seen article claiming that <a href="https://historians.social/tags/Google" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Google</a> is going to switch to requiring use of <a href="https://historians.social/tags/QRcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRcodes</a> (which I loathe) in order to use <a href="https://historians.social/tags/gmail" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#gmail</a>, sometime in the not too distant future. The other email that I have used in the past gradually became useless in recent years (I suspect Gmail of blocking smaller mail servers) so I have just finished migrating everything to my gmail address, but it looks like I now need to migrate elsewhere. Can people recommend a reliable email service?

Terence Eden’s BlogWhy are QR Codes with capital letters smaller than QR codes with lower-case letters?<a href="https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capital-letters-smaller-than-qr-codes-with-lower-case-letters/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capital-letters-smaller-than-qr-codes-with-lower-case-letters/</a>Take a look at these two QR codes. Scan them if you like, I promise there's nothing dodgy in them.     Left is upper-case <code>HTTPS://EDENT.TEL/</code> and right is lower-case <code>https://edent.tel/</code>You can clearly see that the one on the left is a "smaller" QR as it has fewer bits of data in it. Both go to the same URl, the only difference is the casing.What's going on?Your first thought might be that there's a different level of error-correction. QR codes can have increasing levels of redundancy in order to make sure they can be scanned when damaged. But, in this case, they both have Low error correction.The smaller code is "Type 1" - it is 21px * 21px. The larger is "Type 2" with 25px * 25px.The <a href="https://www.qrcode.com/en/about/version.html" rel="nofollow noopener noreferrer" target="_blank">official specification</a> describes the versions in more details. The smaller code should be able to hold 25 alphanumeric character. But <code>https://edent.tel/</code> is only 18 characters long. So why is it bumped into a larger code?Using a decoder like <a href="https://zxing.org/" rel="nofollow noopener noreferrer" target="_blank">ZXING</a> it is possible to see the raw bytes of each code.UPPER<pre><code>20 93 1a a6 54 63 dd 28 35 1b 50 e9 3b dc 00 ec11 ec 11 </code></pre>lower:<pre><code>41 26 87 47 47 07 33 a2 f2 f6 56 46 56 e7 42 e746 56 c2 f0 ec 11 ec 11 ec 11 ec 11 ec 11 ec 11ec 11 </code></pre>You might have noticed that they both end with the same sequence: <code>ec 11</code> Those are "padding bytes" because the data needs to completely fill the QR code. But - hang on! - not only does the UPPER one safely contain the text, it also has some spare padding?The answer lies in the first couple of bytes.Once the raw bytes have been read, a QR scanner needs to know exactly what sort of code it is dealing with. <a href="https://www.thonky.com/qr-code-tutorial/data-encoding#step-3-add-the-mode-indicator" rel="nofollow noopener noreferrer" target="_blank">The first four bits tell it the mode</a>. Let's convert the hex to binary and then split after the first four bits:TypeHEXBINSplitUPPER<code>20 93</code><code>00100000 10010011</code><code>0010 000010010011</code>lower<code>41 26</code><code>01000001 00100110</code><code>0100 000100100110</code>The UPPER code is <code>0010</code> which indicates it is Alphanumeric - the standard says the next 9 bits show the length of data.The lower code is <code>0100</code> which indicates it is Byte mode - the standard says the next 8 bits show the length of data.TypeHEXBINSplitUPPER<code>20 93</code><code>00100000 10010011</code><code>0010 0000 10010</code>lower<code>41 26</code><code>01000001 00100110</code><code>0100 000 10010</code>Look at that! They both have a length of <code>10010</code> which, converted to binary, is 18 - the exact length of the text.Alphanumeric users 11 bits for every two characters, Byte mode uses (you guessed it!) 8 bits per single character.But why is the lower-case code pushed into Byte mode? Isn't it using letters and number?Well, yes. But in order to store data efficiently, Alphanumeric mode only has <a href="https://www.thonky.com/qr-code-tutorial/alphanumeric-table" rel="nofollow noopener noreferrer" target="_blank">a limited subset of characters available</a>. Upper-case letters, and a handful of punctuation symbols: <code>space $ % * + - . / :</code>Luckily, that's enough for a protocol, domain, and path. Sadly, no GET parameters.So, there you have it. If you want the smallest possible physical size for a QR code which contains a URl, make sure the text is all in capital letters. This blog post was exhibited at <a href="https://qrshow.nyc/retrospective.html" rel="nofollow noopener noreferrer" target="_blank">QR Show, NYC</a><a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://shkspr.mobi/blog/tag/qr/" target="_blank">#qr</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://shkspr.mobi/blog/tag/qr-codes/" target="_blank">#QRCodes</a>

Terence Eden🆕 blog! “Why are QR Codes with capital letters smaller than QR codes with lower-case letters?”Take a look at these two QR codes. Scan them if you like, I promise there's nothing dodgy in them.👀 Read more: <a href="https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capital-letters-smaller-than-qr-codes-with-lower-case-letters/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capital-letters-smaller-than-qr-codes-with-lower-case-letters/</a> ⸻ <a href="https://mastodon.social/tags/qr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qr</a> <a href="https://mastodon.social/tags/QRCodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QRCodes</a>

Davva<a href="https://kolektiva.social/tags/Signal" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Signal</a> <a href="https://kolektiva.social/tags/qrcodes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qrcodes</a> <a href="https://www.wired.com/story/russia-signal-qr-code-phishing-attack/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.wired.com/story/russia-signal-qr-code-phishing-attack/</a>

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