This is a stripped down version of https://github.com/kreativekorp/barcode

Use from a PHP script:

include 'qrcode.php';

$generator = new QRCode($data, $options);

/* Output directly to standard output. */
$generator->output_image();

/* Create bitmap image. */
$image = $generator->render_image();
imagepng($image);
imagedestroy($image);

Use with GET or POST:

qrcode.php?s={symbology}&d={data}&{options}

e.g.

qrcode.php?s=qr&d=HELLO%20WORLD&sf=8&ms=r&md=0.8

s - Symbology (type of QR code). One of:

    qr
    qr-l
    qr-m
    qr-q
    qr-h

d - Data. Encode in Shift-JIS for kanji mode.

w - Width of image. Overrides sf or sx.

h - Height of image. Overrides sf or sy.

sf - Scale factor. Default is 4.

sx - Horizontal scale factor. Overrides sf.

sy - Vertical scale factor. Overrides sf.

p - Padding. Default is 0.

pv - Top and bottom padding. Default is value of p.

ph - Left and right padding. Default is value of p.

pt - Top padding. Default is value of pv.

pl - Left padding. Default is value of ph.

pr - Right padding. Default is value of ph.

pb - Bottom padding. Default is value of pv.

bc - Background color in #RRGGBB format.

fc - Foreground color in #RRGGBB format.

md - Module density. A number between 0 and 1. Default is 1.

wq - Width of quiet area units. Default is 1. Use 0 to suppress quiet area.

wm - Width of narrow modules and spaces. Default is 1.