title: How can I save images from a map with cv2.imwrite
body: <p>I want to save with cv2.imwrite images that are contained in a map called &quot;map_result&quot;.
  I tried by converting the map into a list and then save the list with imwrite.
  <code>map_result = preprocessor.get_map(masks)</code>
  <code> list_result = list(map_result)</code>
  <code>cv2.imwrite('map.jpg', list_result)</code><br />
  But it returns:
  <strong>TypeError: Expected Ptr&lt;cv::UMat&gt; for argument 'list_result'</strong>
  How can I save the images correctly in order to display them?</p>