Timber\ImageHelper::get_letterbox_file_url PHP Method

    public static function get_letterbox_file_url($url, $w, $h, $color)
    {
        $au = self::analyze_url($url);
        $op = new Image\Operation\Letterbox($w, $h, $color);
        $new_url = self::_get_file_url($au['base'], $au['subdir'], $op->filename($au['filename'], $au['extension']), $au['absolute']);
        return $new_url;
    }