private static function _createJpeg($imageFile)
{
$gd = @imagecreatefromjpeg($imageFile);
if (!$gd) {
throw new \Exception(sprintf('Could not open "%s". Not a valid %s file.', $imageFile, ImageType::JPEG));
}
return new self($gd, $imageFile, imagesx($gd), imagesy($gd), ImageType::JPEG);
}