An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
Can be 1, 2, 3, 4, 5 for built-in fonts in latin2 encoding (where higher numbers corresponding to larger fonts) or any of your own font identifiers registered with imageloadfont().
x-coordinate of the start
y-coordinate of the start
The character to draw
A color identifier created with imagecolorallocate()
$im = imagecreate(100, 100);
$string = 'Note that the first letter is a N';
$bg = imagecolorallocate($im, 255, 255, 255);
$black = imagecolorallocate($im, 0, 0, 0);
// prints a black "Z" on a white background
imagecharup($im, 3, 10, 10, $string, $black);
The above example will output something similar to: