protected function _crop_dim($x, $y, $w, $h)
{
extract(parent::_crop_dim($x, $y, $w, $h));
$width = $w;
$height = $h;
$this->debug("Cropping image " . $width . "x" . $height . "+{$x}+{$y} based on coords ({$x}, {$y}), ({$w}, {$h})");
$image = $this->create_transparent_image($width, $height);
imagecopy($image, $this->image_data, 0, 0, $x, $y, $width, $height);
$this->image_data = $image;
}
