opencv-python imshow giving errors in mac
The fix that worked best for me was using mathplotlib instead. 
Since you may have to remove all previous versions of OpenCV otherwise and reinstall from source!
I installed opencv-python using pip install, in mac os. Now the cv2.imshow function giving following error

OpenCV Error: Unspecified error (The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script) in cvShowImage

How can I solve this issue? Why doesn't the pip check opencv dependencies?