錯誤提示：
ubuntu opencv imshow() 報錯
windows.cpp報錯
the function is not implemented
If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function 'cvShowImage'
原因：
opencv在ubuntu需要的一些依賴包沒有安裝。按照提示安裝libgtk2.0-dev 和 pkg-config之后 很可能還是報這個錯。
按這個教程，安裝好所有依賴，然后重新安裝opencv：
https://www.cnblogs.com/leoking01/p/8301724.html
sudoapt-get install build-essential libgtk2.0-dev libjpeg-dev libtiff4-dev libjasper-dev libopenexr-dev cmake python-dev python-numpy python-tk libtbb-dev libeigen3-dev yasm libfaac-dev libopencore-amrnb-dev libopencore-amrwb-dev libtheora-dev libvorbis-dev libxvidcore-dev libx264-dev libqt4-dev libqt4-opengl-dev sphinx-common texlive-latex-extra libv4l-dev libdc1394-22-dev libavcodec-dev libavformat-dev libswscale-dev default-jdk ant libvtk5-qt4-dev