code: public function open($file)
      {
          if (strlen($file) >= 1 && $file[0] == '@') {
              try {
                  if ($this->fileLocator instanceof FileLocatorInterface) {
                      $file = $this->fileLocator->locate($file);
                  } else {
                      $this->fileLocator->locateResource($file);
                  }
              } catch (\InvalidArgumentException $exception) {
                  if ($this->throwException || false == $this->fallbackImage) {
                      throw $exception;
                  }
  
                  $file = $this->fallbackImage;
              }
          }
  
          return $this->createInstance($file);
      }
docs: Get a manipulable image instance.
  
  @param string $file the image path
  
  @return ImageHandler a manipulable image instance