/tmp/build/80754af9/opencv_1512687413662/work/modules/highgui/src/window.cpp:611:
error: (-2) 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 function cvShowImage

解決方法：

1、更新PIP

pip install -U pip

2、查看有沒有 opencv-contrib-python，有就卸載重裝

pip uninstall opencv-contrib-python

3、清除該高速緩存

pip cache purge

4、安裝

pip install opencv-contrib-python