/**
  * @return TuringImage
  **/
 private function outputImage(ImageType $imageType)
 {
     $gdImageTypes = imagetypes();
     switch ($imageType->getId()) {
         case ImageType::WBMP:
             if ($gdImageTypes & IMG_WBMP) {
                 header("Content-type: image/vnd.wap.wbmp");
                 imagewbmp($this->imageId);
                 break;
             }
         case ImageType::PNG:
             if ($gdImageTypes & IMG_PNG) {
                 header("Content-type: image/png");
                 imagepng($this->imageId);
                 break;
             }
         case ImageType::JPEG:
             if ($gdImageTypes & IMG_JPG) {
                 header("Content-type: image/jpeg");
                 imagejpeg($this->imageId);
                 break;
             }
         case ImageType::GIF:
             if ($gdImageTypes & IMG_GIF) {
                 header("Content-type: image/gif");
                 imagegif($this->imageId);
                 break;
             }
         default:
             throw new UnimplementedFeatureException('requesting non-supported format');
     }
     return $this;
 }