本文实例讲述了PHP动态生成指定大小随机图片的方法。分享给大家供大家参考，具体如下：
<?php$image_width = 100;$image_height = 100;$image_str = '';if (isset($_GET['w'])){ $image_width = intval($_GET['w']);}if (isset($_GET['h'])){ $image_height = intval($_GET['h']);}if (isset($_GET['s'])){ $image_str = $_GET['s'];}$img = imagecreate($image_width, $image_height);$color = imagecolorallocate($img, mt_rand(157,255), mt_rand(157,255), mt_rand(157,255));imagefilledrectangle($img, 0, $image_height, $image_width, 0, $color);$step = mt_rand(15, 30);$start = mt_rand(0, $step);$color = imagecolorallocate($img, mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));imagesetthickness($img, mt_rand(3, 10));if ($image_height > $image_width){ for ($i=$start; $i<$image_height * 2; $i+=$step) { imageline($img, 0, $i, $i, 0, $color); }}else{ for ($i=$start; $i<$image_width * 2; $i+=$step) { imageline($img, $i, 0, 0, $i, $color); }}if ($image_str != ''){ $black = imagecolorallocate($img, 0, 0, 0); imagestring($img, 12, 5, 5, $image_str, $black);}header('Content-type:image/png');imagepng($img);imagedestroy($img); 
