使用OpenCV时找不到模块cv2

I have installed OpenCV on the Occidentalis operating system (a variant of Raspbian) on a Raspberry Pi, using jayrambhia’s script found here. It installed version 2.4.5.

When I try import cv2 in a Python program, I get the following message:

pi@raspberrypi~$ python cam.py
Traceback (most recent call last)
File "cam.py", line 1, in <module>
    import cv2
ImportError: No module named cv2

The file cv2.so is stored in /usr/local/lib/python2.7/site-packages/...

There are also folders in /usr/local/lib called python3.2 and python2.6, which could be a problem but I’m not sure.

Is this a path error perhaps? Any help is appreciated, I am new to Linux.

First do run these commands inside Terminal/CMD:

conda update anaconda-navigator  
conda update navigator-updater  

Then the issue for the instruction below will be resolved

For windows if you have anaconda installed, you can simply do

pip install opencv-python

or

conda install -c https://conda.binstar.org/menpo opencv

if you are on linux you can do :

pip install opencv-python

or

conda install opencv 

Link1 Link2

For python3.5+ check these links : Link3 , Link4

Update:
if you use anaconda, you may simply use this as well (and hence don’t need to add menpo channel):

conda install -c conda-forge opencv

This happens when python cannot refer to your default site-packages folder where you have kept the required python files or libraries

Add these lines in the code:

import sys

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

or before running the python command in bash move to /usr/local/lib/python2.7/site-packages directory. This is a work around if you don’t want to add any thing to the code.

I solved my issue using the following command :

conda install opencv

Try to add the following line in ~/.bashrc

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

Python3.x User

sudo pip3 install opencv-python

None of the above answers worked for me. I was going crazy until I found this solution below!

Simply run:

sudo apt install python-opencv

For Windows 10 and Python 3.6, this worked for me

pip install opencv-contrib-python

I solved my issue using the following command :

pip install opencv-python

I solve it by running:

pip3 install opencv-python

I have come accross same as this problem i installed cv2 by

pip install cv2

However when i import cv2 module it displayed no module named cv2 error.
Then i searched and find cv2.pyd files in my computer and i copy and paste to site-packages directory

C:\Python27\Lib\site-packages

then i closed and reopened existing application, it worked.

EDIT I will tell how to install cv2 correctly.

1. Firstly install numpy on your computer by

pip install numpy

2. Download opencv from internet (almost 266 mb).
I download opencv-2.4.12.exe for python 2.7. Then install this opencv-2.4.12.exe file.
I extracted to C:\Users\harun\Downloads to this folder.
After installation go look for cv2.py into the folders.
For me

C:\Users\harun\Downloads\opencv\build\python\2.7\x64

in this folder take thecv2.pyd and copy it in to the

C:\Python27\Lib\site-packages

now you can able to use cv2 in you python scripts.

If want to install opencv in virtual environment. Run command in terminal for getting virtual environment list.

conda env list

or jupyter notebook command is

!conda env list

Then update your anaconda.

conda update anaconda-navigator
conda update navigator-updater

Install opencv in your selected environment path.

conda install -c ['environment path'] opencv

Juypter notebook

!conda install --yes --prefix ['environment path'] opencv

IF YOU ARE BUILDING FROM SCRATCH, GO THROUGH THIS

You get No module named cv2.cv. Son, you did all step right, since your sudo make install gave no errors.

However look at this step

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

THE VERY IMPORTANT STEP OF ALL THESE IS TO LINK IT.

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

The moment you choose wise linking, or by brute force just find the cv2.so file if that exist or not

Here I am throwing my output.

    Successfully installed numpy-1.15.3
(cv) demonLover-desktop:~$ cd ~/.virtualenvs/cv/lib/python2.7/site-packages/
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ln -s /usr/local/lib/python2.7/site-packages/cv2.so cv2.so
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ pip list
Package    Version
---------- -------
numpy      1.15.3 
pip        18.1   
setuptools 40.5.0 
wheel      0.32.2 
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ python
Python 2.7.12 (default, Dec  4 2017, 14:50:18) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named cv2
>>> 
[2]+  Stopped                 python
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls /usr/local/lib/python2.7/site-packages/c
ls: cannot access '/usr/local/lib/python2.7/site-packages/c': No such file or directory
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls /usr/local/lib/python2.7/site-packages/
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ deactivate 
demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls /usr/local/lib/python2.7/site-packages/
demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls
cv2.so  easy_install.py  easy_install.pyc  numpy  numpy-1.15.3.dist-info  pip  pip-18.1.dist-info  pkg_resources  setuptools  setuptools-40.5.0.dist-info  wheel  wheel-0.32.2.dist-info
demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls /usr/local/lib/python2.7/site-packages/
demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls -l  /usr/local/lib/python2.7/site-packages/
total 0
demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls
cv2.so  easy_install.py  easy_install.pyc  numpy  numpy-1.15.3.dist-info  pip  pip-18.1.dist-info  pkg_resources  setuptools  setuptools-40.5.0.dist-info  wheel  wheel-0.32.2.dist-info
demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ workon cv
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ python
Python 2.7.12 (default, Dec  4 2017, 14:50:18) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named cv2
>>> 
[3]+  Stopped                 python
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ find / -name "cv2.so"
find: ‘/lost+found’: Permission denied
find: ‘/run/udisks2’: Permission denied
find: ‘/run/docker’: Permission denied
find: ‘/run/exim4’: Permission denied
find: ‘/run/lightdm’: Permission denied
find: ‘/run/cups/certs’: Permission denied
find: ‘/run/sudo’: Permission denied
find: ‘/run/samba/ncalrpc/np’: Permission denied
find: ‘/run/postgresql/9.5-main.pg_stat_tmp’: Permission denied
find: ‘/run/postgresql/10-main.pg_stat_tmp’: Permission denied
find: ‘/run/lvm’: Permission denied
find: ‘/run/systemd/inaccessible’: Permission denied
find: ‘/run/lock/lvm’: Permission denied
find: ‘/root’: Permission denied
^C
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ sudofind / -name "cv2.so"
sudofind: command not found
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ^C
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ sudo find / -name "cv2.so"
[sudo] password for app: 
find: ‘/run/user/1000/gvfs’: Permission denied
^C
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ sudo find /usr/ -name "cv2.so"
/usr/local/lib/python2.7/dist-packages/cv2.so
^C
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ln -s /usr/local/lib/python2.7/dist-packages/ccv2.so cv2.so
click/                        clonevirtualenv.pyc           configparser-3.5.0.dist-info/ configparser.py               cv2.so                        cycler.py
clonevirtualenv.py            concurrent/                   configparser-3.5.0-nspkg.pth  configparser.pyc              cycler-0.10.0.dist-info/      cycler.pyc
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ln -s /usr/local/lib/python2.7/dist-packages/cv2.so cv2.so
ln: failed to create symbolic link 'cv2.so': File exists
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ rm cv2.so 
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ln -s /usr/local/lib/python2.7/dist-packages/cv2.so cv2.so
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ ls
cv2.so  easy_install.py  easy_install.pyc  numpy  numpy-1.15.3.dist-info  pip  pip-18.1.dist-info  pkg_resources  setuptools  setuptools-40.5.0.dist-info  wheel  wheel-0.32.2.dist-info
(cv) demonLover-desktop:~/.virtualenvs/cv/lib/python2.7/site-packages$ python
Python 2.7.12 (default, Dec  4 2017, 14:50:18) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> 

My step will only help, if your built is done right.

I solve this by run code pip install opencv_contrib_python

Try this out:

sudo ldconfig

sudo nano /etc/ld.so.conf.d/opencv.conf

and add this following line in the opencv.conf not in the command window

/usr/local/lib

Then:

sudo ldconfig

sudo nano /etc/bash.bashrc

and add this two lines in the bash.bashrc not in the command window

PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig       
export PKG_CONFIG_PATH

at last reboot your Pi sudo reboot now

and try import cv2

Another way I got opencv to install and work was inside visual studio 2017 community. Visual studio has a nice python environment with debugging.
So from the vs python env window I searched and added opencv. Just thought I would share because I like to try things different ways and on different computers.

I had the same problem, just couldn’t figure it out with opencv2 and opencv3 installed into /opt/opencv and opencv3 respectively. Turned out that bloody anaconda install of opencv in my home directory was first on path and mangled opencv. Removed it and started using /opt/opencv3/lib as defined in /etc/ld.so.conf.d/opencv.conf. Worked perfectly first go. Do you have anaconda installed? Could be the issue.