HI!
i use the following function to resize image. It is ok with jpg or png but not with tiff..
Can you help me to fin error please?

function image_resize($src, $dst, $width, $height, $crop=0){

if(!list($w, $h) = getimagesize($src)) return "Unsupported picture type!"; //calcola le dimensioni dell'immagine originale

$type = strtolower(substr(strrchr($src,"."),1));
if($type == 'jpeg') $type = 'jpg';
switch($type){
case 'bmp': $img = imagecreatefromwbmp($src); break;
case 'gif': $img = imagecreatefromgif($src); break;
case 'jpg': $img = imagecreatefromjpeg($src); break;
case 'png': $img = imagecreatefrompng($src); break;
case 'tif': $img = imagecreate($src); break;
default : return "Unsupported picture type!";
}

// resize
if($crop){
if($w < $width or $h < $height) return "Picture is too small!";
$ratio = max($width/$w, $height/$h);
$h = $height / $ratio;
$x = ($w - $width / $ratio) / 2;
$w = $width / $ratio;

}
else{
if($w < $width and $h < $height) return "Picture is too small!";
$ratio = min($width/$w, $height/$h);
$width = $w * $ratio;
$height = $h * $ratio;
$x = 0;
}

$new = imagecreatetruecolor($width, $height);

// preserve transparency
if($type == "gif" or $type == "png"){
imagecolortransparent($new, imagecolorallocatealpha($new, 0, 0, 0, 127));
imagealphablending($new, false);
imagesavealpha($new, true);
}

//echo 'new:'.$new.'<br>img:'.$img.'<br>x:'.$x.'<br>widht:'.$width.'<br>height:'.$height.'<br>w:'.$w.'<br>h :'.$h;die;
imagecopyresampled($new, $img, 0, 0, $x, 0, $width, $height, $w, $h);

switch($type){
case 'bmp': imagewbmp($new, $dst); break;
case 'gif': imagegif($new, $dst); break;
case 'jpg': imagejpeg($new, $dst); break;
case 'png': imagepng($new, $dst); break;
}
return true;
}