Install OpenCV for Python on Ubuntu, get ImportError: no module named cv2.cv

Question

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

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

The installation seemed to work correctly, no errors, the script ended up exiting

OpenCV 2.4.9 ready to be used 

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

 $ python opencv.py Traceback (most recent call last): File "opencv.py", line 1, in <module> 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 is installed in the current directory that I was in when I ran the installation script, this is a subdirectory of my home folder.

Others that get this import error after installation seem to have a problem with the path, and they are fortunate enough to add this to their code:

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

or update their PYTHONPATH using the same directory. I tried to add this code, it does not matter. I do not see any files in the "site-packages" directory. Should I do the installation in this directory? I assume that the installation instructions would have to spell it out. I suspect my problem is that Python cannot find the OpenCV installation, but I'm not sure how to do this.

Please help me get a convenient installation of OpenCV as simple as possible.

Answer 1

I think you do not have the python-opencv package.

I had exactly the same problem and

 sudo apt-get install python-opencv 

solved the problem for me.

You can install opencv at the following link https://www.learnopencv.com/install-opencv3-on-ubuntu/ This works for me. apt-get install does not contain many opencv packages

Answer 2

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

 conda install opencv 

worked for me.

Answer 3

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

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

Answer 4

Use pip:

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

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

And when you add the path to PYTHONPATH with sys, PYTHONPATH always restarts to its default values ​​when you close the Python shell. Check out this thread:

Constantly add directory to PYTHONPATH

First add openCV to your path (short guide):

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

after that install packages other than python, pyopencv depends on:

 sudo apt-get build-dep python-opencv 

finally use pip:

 pip install pyopencv 

Alternatively, you can check out this tutorial to install openCV on ubuntu 14.04 LTS

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

Answer 5

Try conda install -c conda-forge opencv if you use anaconda it works!

Answer 6

Find where cv2.so , for example /usr/local/lib/python2.7/dist-packages , then add it to 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 do not forget to open another terminal, it may be work, and I solved my problem. Hope this helps you.

Answer 7

Make sure cv2.so has compiled: / usr / local / lib / python 2.7 / site-packages Then export this path like this

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

Same as answer here

Answer 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 guide . 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 textbook is important. In particular, be sure to call sudo make install .

Answer 9

I found the solution in the manual 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 code. The process was very smooth, if I knew, I would start from this, instead of trying to find an easier way to install. Hope this information helps someone.

Answer 10

Create a symlink to OpenCV. For example:

 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 

Answer 11

If you are really sure that you installed cv2, but it does not give module errors. There is a solution for this. Perhaps you have a cv2.so file in your directory

 /usr/local/lib/python2.7/site-packages/cv2.so 

move this cv2.so file to

 /usr/lib/python2.7/site-packages 

copy the file to the package sites directory

Answer 12

if you use the pycharm platform, it’s very easy to go to view => tool window ==> the python console, after that you will see the console below with [1]: type !pip install opencv-python

Answer 13

Try using: from cv2 import cv

It works for me.

Answer 14

For those who are trying to use 3.1.0, but after installing python they say "cv2 module not found."

Most likely you have python but no python-dev.

 sudo apt-get install python-dev 

then reinstall 3.1.0 and it will work.

Answer 15

It seemed to me that this works on Max OSX: https://anaconda.org/menpo/opencv3

 conda install -c menpo opencv3=3.1.0 

I confirmed that you can import cv2 into python using python2.7 and python3

Answer 16

For me, this problem arose because I did not properly link the cv2.so file in the ~/.virtualenvs/cv/lib/python3.5/site-packages folder (your virualenv name cannot be "cv", your python version may not be 3.5 - adjust accordingly).

If you go to the ~/.virtualenvs/cv/lib/python3.5/site-packages and ls folder, the cv2.so file should appear in blue (Ubuntu 16.04), showing that it is connected. You can check the location of the link by typing: readlink cv2.so

If cv2.so is displayed in red (like mine), rm file and type: (for my python 3.5 installation)

 ln -s /usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-x86_64-linux-gnu.so cv2.so 

OR (if you have python 3.6)

 ln -s /usr/local/lib/python3.6/dist-packages/cv2.cpython-36m-x86_64-linux-gnu.so cv2.so 

If you are running python 2.6 or python 2.7, enter instead:

 ln -s /usr/local/lib/python2.7/dist-packages/cv2.so cv2.so 

If the files cv2.so or cv2.cpython-36m-x86_64-linux-gnu.so do not exist at your location /usr/local/lib/python***/dist-packages , check to see if they are in the /usr/local/lib/python***/sites-packages folder /usr/local/lib/python***/sites-packages . If so, adjust the path accordingly. If not, something went wrong with your opencv installation.

This answer was inspired by the information here: https://www.pyimagesearch.com/2016/10/24/ubuntu-16-04-how-to-install-opencv/

Answer 17

This is a complete installation nightmare, but I will give one more hope that you can avoid building opencv from the source code:

pip install opencv-contrib-python