knowledge/technology/tools/QR Code.md

obj	wiki	rev
concept	https://en.wikipedia.org/wiki/QR_code	2024-03-13

QR Code

The quick response, or QR, Code is a two-dimensional version of the Barcode able to convey a wide variety of information almost instantly with the scan of a mobile device.

One can encode URLs, Contacts (in vCard format), WiFi-Credentials, Locations or other ASCII data.

Creating QR Codes

You can create QR Codes with qrencode.
Usage: qrencode [-o FILENAME] [OPTION]... [STRING]
Encode input data in a QR Code and save as a PNG image.

Option	Description
-o FILENAME, --output=FILENAME	write image to FILENAME. If '-' is specified, the result will be output to standard output.
-r FILENAME, --read-from=FILENAME	read input data from FILENAME.
-s NUMBER, --size=NUMBER	specify module size in dots (pixels). (default=3)
-l {LMQH}, --level={LMQH}	specify error correction level from L (lowest) to H (highest). (default=L)
-m NUMBER, --margin=NUMBER	specify the width of the margins. (default=4)
-d NUMBER, --dpi=NUMBER	specify the DPI of the generated PNG. (default=72)
-c, --casesensitive	encode lower-case alphabet characters in 8-bit mode. (default)
-i, --ignorecase	ignore case distinctions and use only upper-case characters.