ridimensionamento immagine (la voglio meno pesante!!!)

[tommyxxx]

Ho trovatoquesto che credo che sia quello che cerco ma ho bisogno di qualche spiegazione per usarlo.....

  function OutThumb($file, $w, $h){
  $size = getimagesize($$file);
  if( $size[2] == 2 ){$im = @imagecreatefromjpeg($file);}
  elseif( $size[2] == 1 ){$im = @imagecreatefromgif($file);}
  elseif( $size[2] == 3 ){$im = @imagecreatefrompng($file);}

  $newwidth = $size[0];
  $newheight = $size[1];

  if( $newwidth > $w ){
    $newheight = ($w / $newwidth) * $newheight;
    $newwidth = $w;
  }
  if( $newheight > $h ){
    $newwidth = ($h / $newheight) * $newwidth;
    $newheight = $h;
  }

  if( (GDVersion() == 2) AND ($size[2] != 1) ){
    $new = imagecreatetruecolor($newwidth, $newheight);
    imagecopyresampled($new, $im, 0, 0, 0, 0, $newwidth, $newheight, $size[0], $size[1]);
  }
  else{
    $new = imagecreate($newwidth, $newheight);
    imagecopyresized($new, $im, 0, 0, 0, 0, $newwidth, $newheight, $size[0], $size[1]);
  }
  header('Content-Type: ' . $size['mime']);
  if( $size[2] == 2 ){@imagejpeg($new, '', 100);}
  elseif( $size[2] == 1 ){@imagegif($new);}
  elseif( $size[2] == 3 ){@imagepng($new);}
  @imagedestroy($im);
  @imagedestroy($new);
}