bool imagecharup ( resource $image , int $font , int $x , int $y , string $c , int $color )

<?php

$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);

// 在白色的背景上输出黑色的 "Z"
imagecharup($im, 3, 10, 10, $string, $black);

header('Content-type: image/png');
imagepng($im);