Rediger gif billede?

Hej,
jeg har denne kode:

<?php
function tump($maxsize, $imgpath) {
    $sizes = getimagesize($imgpath);
    $biggestsize = max($sizes[0],$sizes[1]);
    $scale = $maxsize/$biggestsize;
    $smallestsize = min($sizes[0],$sizes[1]);
    $newsize = $scale*$smallestsize;
    header("Content-type: image/jpeg");
    $srcimage = ImageCreateFromJPEG($imgpath);
    if (max($sizes[0],$sizes[1]) == $sizes[0]) {
    $destimage = imagecreatetruecolor($maxsize, $newsize);
    imagecopyresampled($destimage,$srcimage,0,0,0,0,$maxsize,$newsize,$sizes[0],$sizes[1]);
    } else {
    $destimage = imagecreatetruecolor($newsize, $maxsize);
    imagecopyresampled($destimage,$srcimage,0,0,0,0,$newsize,$maxsize,$sizes[0],$sizes[1]);
    }
    return imagejpeg($destimage);
}
print tump("50", "http://www.wssa.net/photo&info/bmp/star-flower.flowers.jpg")
?>

virker fint, men jeg vil gerne have mulighed for at den også kan bruge gif og png billeder?