protected function getImagePath($filename)
    {
        // find file
        foreach (config('imagecache.paths') as $path) {
            // don't allow '..' in filenames
            $image_path = $path.'/'.str_replace('..', '', $filename);
            if (file_exists($image_path) && is_file($image_path)) {
                // file found
                return $image_path;
            }
        }

        // file not found
        abort(404);
    }