Installing OpenCV for Python on Ubuntu, getting ImportError: No module named cv2.cv

Python Programming

Question or problem about Python programming:

I have an Ubuntu 14.04 system, on which I want to install OpenCV and use it with Python 2.x.

I installed OpenCV using the instructions here:
https://help.ubuntu.com/community/OpenCV

The install seemed to run properly, no errors, the script ended with output

OpenCV 2.4.9 ready to be used

When I try to run the sample Python script, I get the following:

$ python opencv.py
Traceback (most recent call last):
  File "opencv.py", line 1, in 
    from cv2.cv import *
ImportError: No module named cv2.cv

I suspect I know why, I just don’t know how to fix it. OpenCV installed to the current directory I was in when I ran the install script, it’s a subdirectory of my home folder.

Others who get this import error after install seem to be having a path issue, and have luck adding this to their code:

import sys
sys.path.append('/usr/local/lib/python2.7/site-packages')

or updating their PYTHONPATH with that same directory. I tried adding that code, it doesn’t make a difference. I don’t see any files in the “site-packages” directory. Should I have done the install in that directory? I imagine the installation instructions would have spelled that out. I suspect that my problem has to do with Python not finding the OpenCV install, but I’m not sure how to proceed.

Please help me get a usable install of OpenCV as simply as possible.

How to solve the problem:

Solution 1:

I think you don’t have the python-opencv package.

I had the exact same problem and

sudo apt-get install python-opencv

solved the issue for me.

you can install opencv from the following link
https://www.learnopencv.com/install-opencv3-on-ubuntu/
It works for me .
apt-get install doesnt contain many packages of opencv

Solution 2:

I also had this issue. Tried different things. But finally

conda install opencv

worked for me.

Solution 3:

If you want as simple as possible, install from the repository:

sudo apt-get install python-opencv libopencv-dev python-numpy python-dev

Solution 4:

Use pip:


https://pypi.python.org/pypi/pip

$ pip install SomePackage
  [...]
  Successfully installed SomePackage

And when you add a path to PYTHONPATH with sys, PYTHONPATH it’s always restarted to default values when you close your Python shell. Check this thread:


Permanently add a directory to PYTHONPATH

First add openCV to your path (Quick guide):


https://help.ubuntu.com/community/OpenCV

after that, install the non-python packages pyopencv depends on:

sudo apt-get build-dep python-opencv

finally, use pip:

pip install pyopencv

Also, you can check this tutorial to install openCV in ubuntu 14.04 LTS

Installing OpenCV 2.4.9 in Ubuntu 14.04 LTS


Solution 5:

Try conda install -c conda-forge opencv if you are using anaconda, it works!

Solution 6:

Find where the cv2.so is, for example /usr/local/lib/python2.7/dist-packages, then add this into your ~/.bashrc by doing:

sudo gedit ~/.bashrc

and add

export PYTHONPATH=/usr/local/lib/python2.7/dist-packages:$PYTHONPATH

In the last line

And then remember to open another terminal, this can be work, and I have solve my problem. Hope it can help you.

Solution 7:

Verify if cv2.so did compile, should be placed in:
/usr/local/lib/python2.7/site-packages
Then export that path like this

export PYTHONPATH=/usr/local/lib/python2.7/site-packages:$PYTHONPATH

Same as in the answer here

Solution 8:

My environment:

  • Ubuntu 15.10
  • Python 3.5

Since none of the previous answers worked for me, I downloaded OpenCV 3.0 from http://opencv.org/downloads.html and followed the installation manual. I used the following cmake command:

$ ~/Programs/opencv-3.0.0$ cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=/usr/local -D PYTHON3_EXECUTABLE=/usr/bin/python3.5 -D PYTHON_INCLUDE_DIR=/usr/include/python3.5 -D PYTHON_INCLUDE_DIR2=/usr/include/x86_64-linux-gnu/python3.5m -D PYTHON_LIBRARY=/usr/lib/x86_64-linux-gnu/libpython3.5m.so -D PYTHON3_NUMPY_INCLUDE_DIRS=/usr/lib/python3/dist-packages/numpy/core/include/ -D PYTHON3_PACKAGES_PATH=/usr/lib/python3/dist-packages ..

Each step of the tutorial is important. Particularly, don’t forget to call sudo make install.

Solution 9:

I found a solution in the guide here:

http://www.samontab.com/web/2014/06/installing-opencv-2-4-9-in-ubuntu-14-04-lts/

I resorted to compiling and installing from source. The process was very smooth, had I known, I would have started with that instead of trying to find a more simple way to install. Hopefully this information is helpful to someone.

Solution 10:

Create a symbolic link to OpenCV. Eg:

cd ~/.virtualenvs/cv/lib/python2.7/site-packages/
ln -s /usr/local/lib/python2.7/dist-packages/cv2.so cv2.so
ln -s /usr/local/lib/python2.7/dist-packages/cv.py cv.py

Hope this helps!