protected function addWatermarkFilterIfExists(&$set, $width, $height)
    {
        if( isset($set['watermark']) )
        {
            if( ! empty($set['watermark'][1])) 
            {
                $set['filters'][] = ['target', [$set['watermark'][1]]];
            }

            if( ! empty($set['watermark'][2])) 
            {
                $set['filters'][] = ['margin', [$set['watermark'][2]]];
            }

            $set['filters'][] = ['mix', [$set['watermark'][0]]];
        }  
    }