I'd like to generate a full-page QR code from the command line. The following command sort of accomplishes this: qrencode -o- https://example.net | convert png:- -gravity center -units pixelsperinch -density 300 -resize 2551x3295 -extent 2551x3295 qrcode.pdf Unfortunately, the resulting QR code is quite blurry, as though imagemagick is doing some sort of unwanted antialiasing. Is there a way to make the code completely crisp, or just a better/simpler approach to generating a PDF file with a full-page QR code?

It happens to me regularly that I get a low quality raster image of a QR code and I need it in better quality. This works in principle: zbarimg --quiet --raw qr-bad.png | qrencode -t SVG -o qr-good.svg But sometimes it's important to keep the QR code exactly the same. Is there a way to detect the parameters of the original and keep them the same? I'd like the result to have exactly the same pattern of white and black blocks.

I need to generate several thousand qr codes of simple IDs (1234, 1235, 1236, ...) and want to be able to also make them human readable. qrencode is a really cool tool to generate qr-codes, BUT no way to add a subtitle there. Any ideas?

I installed a command-line QR-code generator: apt install qrencode I used the following format, so the QR scanner knows what to do with the content: WIFI:T:WPA;S:;P:;; generating the QR image file then works like this: qrencode "WIFI:T:WPA;S:My_Network;P:My_very_secure_Password;;" -o wifi_login.png this generates an image file wifi_login.png with the QR encoded string. while the option -o FILENAME or --output=FILENAME makes qrencode write the generated image to this FILENAME. - can be used to print to standard output. The whole procedure works pretty well with MAC devices, but not with Android. **Is there anything wrong with the string, making it not Android-compatible?**

I want to generate a QR code of my 4096-bit armored GPG private key. The key is so big, the program qrencode seems to fail because of its size. $ gpg --export-secret-keys --armor > ~/private.key $ ./qrencode -o test.png Failed to encode the input data: Numerical result out of range How can I make that happen? Are there alternative programs to qrencode which can handle a very big GPG key? I want to print it on paper as this security.SE question suggested. --- The comments of @geruetzel and @ cuonglm are addressing this version of my question .