Running OpenCV from a Python virtualenv

11,525

Solution 1

Fired up a virtualenv and followed this guide: http://www.samontab.com/web/2011/06/installing-opencv-2-2-in-ubuntu-11-04/ , up until manipulating and copying the cv shared objects. Instead, I copied cv.so (from my OpenCV-2.2.0/lib directory) to my virtualenv site-packages (eg. env/lib/python2.7/site-packages/). Once cv.so was in my environment, I was able to import cv within python.

Solution 2

Here is the cleanest way, using pyenv and the virtualenv plug-in.

Install Python with shared library support (so we get a libpython2.7.dylib on Mac OS X or libpython2.7.so on Linux).

env PYTHON_CONFIGURE_OPTS="--enable-shared" pyenv install -v 2.7.6

Create the virtualenv, based on the version of python we just installed.

pyenv virtualenv 2.7.6 myvirtualenv

Activate the virtualenv.

pyenv shell myvirtualenv
pyenv rehash

Install numpy. Otherwise opencv will fail to link itself to Python correctly.

pip install numpy

Set the prefix of the python install.

PREFIX_MAIN=`pyenv virtualenv-prefix`

Set the prefix of the environment. (sic! The name of these pyenv commands are a bit deceptive!)

PREFIX=`pyenv prefix`

Now configure and install opencv. Notice that the opencv binaries and packages will be installed in our virtualenv while the dynamic library and includes of the Python install is used.

cd openCV2.4
mkdir release
cd release
cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX="$PREFIX" -DPYTHON_EXECUTABLE="$PREFIX"/bin/python2.7 -DPYTHON_LIBRARY="$PREFIX_MAIN"/lib/libpython2.7.so -DPYTHON_INCLUDE_DIR="$PREFIX_MAIN"/include/python2.7 -DPYTHON_PACKAGES_PATH="$PREFIX"/lib/python2.7/site-packages/ ..
make install

(On OSX, replace libpython2.7.so with libpython2.7.dylib.)

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Updated on September 15, 2022

Comments

  • runfalk
    runfalk over 1 year

    I'm trying to install OpenCV within a virtualenv on my Ubuntu Server 12.04. I found a thread discussing this but managed to extract no information from it.

    I tried using pip install pyopencv but it failed.

    ...
    package/extras/core/ndarray.cpp:598:1:   instantiated from here
    
    package/extras/core/ndarray.cpp:546:9: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘Py_intptr_t {aka long int}’ [-Wformat]
    
    package/extras/core/ndarray.cpp: In function ‘boost::python::api::object sdcpp::from_ndarray_impl(const sdcpp::ndarray&) [with T = cv::Scalar_<double>]’:
    
    package/extras/core/ndarray.cpp:601:1:   instantiated from here
    
    package/extras/core/ndarray.cpp:546:9: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘Py_intptr_t {aka long int}’ [-Wformat]
    
    package/extras/core/ndarray.cpp: In function ‘boost::python::api::object sdcpp::from_ndarray_impl(const sdcpp::ndarray&) [with T = cv::Range]’:
    
    package/extras/core/ndarray.cpp:604:1:   instantiated from here
    
    package/extras/core/ndarray.cpp:546:9: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘Py_intptr_t {aka long int}’ [-Wformat]
    
    error: command 'gcc' failed with exit status 1
    

    This error only occurs the second time I run pip install. If I delete the remainging build/ folder I get this error.

    -- Configuring incomplete, errors occurred!
    
    Configuring PyOpenCV via CMake...
    
    Error: error occurred while running CMake to configure PyOpenCV.
    
    You may want to manually configure PyOpenCV by running cmake's tools:
    
        mkdir build
    
        cd build
    
        cmake-gui ..    OR    cmake ..
    
        cd ..
    
    ----------------------------------------
    Command python setup.py egg_info failed with error code 255
    

    I have at least the following apt packages installed.

    build-essential
    uuid-dev
    python-dev
    python-pip
    libpq-dev
    cmake
    libboost-dev
    libcv-dev
    libcvaux-dev
    libboost-python-dev
    libboost1.48-dev
    

    How can I install OpenCV within my virtualenv?

  • Nate Parsons
    Nate Parsons over 11 years
    Thanks, copying the shared objects was what I was missing! Only difference was I copied cv.py[c] and cv2.so from /usr/lib/pymodules, analagous to github.com/ingenuitas/SimpleCV#installation
  • Cătălin George Feștilă
    Cătălin George Feștilă about 11 years
    I have all this opencv.i386 : Collection of algorithms for computer vision opencv-devel.i386 : Development files for using the OpenCV library opencv-python.i386 : Python bindings for apps which use OpenCV I use Fedora , the error is:"/include/c++/4.3.2/bits/stl_move.h:87: error: within this context" I using virtualenv.py .
  • Burhan Khalid
    Burhan Khalid about 11 years
    @CatalinFestila you should open another discussion as your question is different than what this is talking about.