GD Lubrary ( I use zenPhoto 1.2.9 ). This is the i.php showing code of images:
`if (!$debug) {
if(file_exists($path)) {
header('Last-Modified: '.gmdate("D, d M Y H:i

", $fmt).' GMT');
$suffix = getSuffix($newfilename);
$imageSize = filesize($path);
switch ($suffix) {
case 'bmp':
$suffix = 'wbmp';
break;
case 'jpg':
$suffix = 'jpeg';
break;
case 'png':
case 'gif':
case 'jpeg':
break;
default:
pageError(405, gettext("Method Not Allowed"));
exit();
}
$imageFunction = 'imagecreatefrom'.$suffix;
if(function_exists($imageFunction)) {
$imageObject = $imageFunction($path);
if(is_resource($imageObject)) {
$imageShowFunction = 'image'.$suffix;
if(function_exists($imageShowFunction)) {
header('Content-Type: image/'.$suffix);
header('Content-Length: '.$imageSize);
$imageShowFunction($imageObject);
imagedestroy($imageObject);
unset($imageFunction);
unset($imageObject);
unset($imageShowFunction);
}
}
}
/*if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && trim($_SERVER['HTTP_IF_MODIFIED_SINCE']) == gmdate("D, d M Y H:i

", $fmt).' GMT') {
header('HTTP/1.0 304 Not Modified');
header('Content-Length: 0');
}*/
}
} else {
echo "\nImage: <img src=\"" . $path ."\" />
";
}`