Install OpenCv for python in Linux

Open cv is a powerful tool for image processing！
I’ll guided you to install open cv for python in Linux platform.

0. Anaconda

If you installed Anacondain you computer, you may install opencvby this command:

conda install opencv

But this may not work, since in Linux, a lot of differences existed.
You may meet this mistakes:

Thefunction is not implemented. Rebuild the library with Windows, GTK+ 2.x orCarbon support. If you are on Ubuntu or Debian, install libgtk2.0‑dev and pkg‑config, then re‑runcmake or configure script

If so, you should use conda uninstall opencv and then go to the following steps.

1. Follow the official guidance

https://docs.opencv.org/trunk/d2/de6/tutorial_py_setup_in_ubuntu.html

2. Refer to website

https://jingyan.baidu.com/article/14bd256e466474bb6d2612db.html

3. Mistakes I meet

3.1 ‘NppiGraphcutState’

When I reached 95， I got ‘NppiGraphcutState’ has not been declared as the follow website
https://devtalk.nvidia.com/default/topic/986950/opencv-installation-problem-nppigraphcutinitalloc-not-declared/

This is caused by the Incompatible between cuda8.0 and opencv2(or opencv3).
To solve this:
Modify opencv-3.0.0/modules/cudalegacy/src/graphcuts.cppfile.
In detail:
change

#if !defined (HAVE_CUDA) || defined (CUDA_DISABLER) 

to

#if !defined (HAVE_CUDA) || defined (CUDA_DISABLER) || (CUDART_VERSION >= 8000)

Then, re-make. I passed.

3.1 import error

Even I finished make process and I also did

sudo /bin/bash -c 'echo "/usr/local/lib" > /etc/ld.so.conf.d/opencv.conf'

sudo ldconfig

But I still can’t import cv2in python.
To solve this, I used

cd /home/xx/anaconda2/lib/python2.7/site-packages/
ln -s /usr/local/lib/python2.7/site-packages/cv2.so cv2.so

Thing done!