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LearnOpenCV

Install OpenCV3 on Ubuntu

Vaibhaw Singh Chandel
June 6, 2017 163 Comments
Compile Install OpenCV 3

By 163 Comments

Install OpenCV 3 on Ubuntu

In this post, we will provide step by step instructions for installing OpenCV 3 (C++ and Python) on Ubuntu.

If you are still not able to install OpenCV on your system, but want to get started with it, we suggest using our docker images with pre-installed OpenCV, Dlib, miniconda and jupyter notebooks along with other dependencies as described in this post.
You can also use our Installation Script for OpenCV-3 and OpenCV-4 for Ubuntu 16.04 as described in this article.

Step 1: Update packages

sudo apt-get update
sudo apt-get upgrade

Step 2: Install OS libraries

Remove any previous installations of x264</h3>
sudo apt-get remove x264 libx264-dev

We will Install dependencies now

sudo apt-get install build-essential checkinstall cmake pkg-config yasm
sudo apt-get install git gfortran
sudo apt-get install libjpeg8-dev libjasper-dev libpng12-dev

# If you are using Ubuntu 14.04
sudo apt-get install libtiff4-dev
# If you are using Ubuntu 16.04
sudo apt-get install libtiff5-dev

sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev
sudo apt-get install libxine2-dev libv4l-dev
sudo apt-get install libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev
sudo apt-get install qt5-default libgtk2.0-dev libtbb-dev
sudo apt-get install libatlas-base-dev
sudo apt-get install libfaac-dev libmp3lame-dev libtheora-dev
sudo apt-get install libvorbis-dev libxvidcore-dev
sudo apt-get install libopencore-amrnb-dev libopencore-amrwb-dev
sudo apt-get install x264 v4l-utils

# Optional dependencies
sudo apt-get install libprotobuf-dev protobuf-compiler
sudo apt-get install libgoogle-glog-dev libgflags-dev
sudo apt-get install libgphoto2-dev libeigen3-dev libhdf5-dev doxygen

Step 3: Install Python libraries

sudo apt-get install python-dev python-pip python3-dev python3-pip
sudo -H pip2 install -U pip numpy
sudo -H pip3 install -U pip numpy

We will use Virtual Environment to install Python libraries. It is generally a good practice in order to separate your project environment and global environment.

# Install virtual environment
sudo pip2 install virtualenv virtualenvwrapper
sudo pip3 install virtualenv virtualenvwrapper
echo "# Virtual Environment Wrapper"  >> ~/.bashrc
echo "source /usr/local/bin/virtualenvwrapper.sh" >> ~/.bashrc
source ~/.bashrc

############ For Python 2 ############
# create virtual environment
mkvirtualenv facecourse-py2 -p python2
workon facecourse-py2

# now install python libraries within this virtual environment
pip install numpy scipy matplotlib scikit-image scikit-learn ipython

# quit virtual environment
deactivate
######################################

############ For Python 3 ############
# create virtual environment
mkvirtualenv facecourse-py3 -p python3
workon facecourse-py3

# now install python libraries within this virtual environment
pip install numpy scipy matplotlib scikit-image scikit-learn ipython

# quit virtual environment
deactivate
######################################

Step 4: Download OpenCV and OpenCV_contrib

We will download opencv and opencv_contrib packages from their GitHub repositories.

Step 4.1: Download opencv from Github

git clone https://github.com/opencv/opencv.git
cd opencv
git checkout 3.3.1
cd ..
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Step 4.2: Download opencv_contrib from Github

git clone https://github.com/opencv/opencv_contrib.git
cd opencv_contrib
git checkout 3.3.1
cd ..

Step 5: Compile and install OpenCV with contrib modules

Step 5.1: Create a build directory

cd opencv
mkdir build
cd build

Step 5.2: Run CMake

cmake -D CMAKE_BUILD_TYPE=RELEASE \
      -D CMAKE_INSTALL_PREFIX=/usr/local \
      -D INSTALL_C_EXAMPLES=ON \
      -D INSTALL_PYTHON_EXAMPLES=ON \
      -D WITH_TBB=ON \
      -D WITH_V4L=ON \
      -D WITH_QT=ON \
      -D WITH_OPENGL=ON \
      -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \
      -D BUILD_EXAMPLES=ON ..

Step 5.3: Compile and Install

# find out number of CPU cores in your machine
nproc
# substitute 4 by output of nproc
make -j4
sudo make install
sudo sh -c 'echo "/usr/local/lib" >> /etc/ld.so.conf.d/opencv.conf'
sudo ldconfig

Step 5.4: Create symlink in virtual environment

Depending upon Python version you have, paths would be different. OpenCV’s Python binary (cv2.so) can be installed either in directory site-packages or dist-packages. Use the following command to find out the correct location on your machine.

find /usr/local/lib/ -type f -name "cv2*.so"

It should output paths similar to one of these (or two in case OpenCV was compiled for both Python2 and Python3):

############ For Python 2 ############
## binary installed in dist-packages
/usr/local/lib/python2.6/dist-packages/cv2.so
/usr/local/lib/python2.7/dist-packages/cv2.so
## binary installed in site-packages
/usr/local/lib/python2.6/site-packages/cv2.so
/usr/local/lib/python2.7/site-packages/cv2.so

############ For Python 3 ############
## binary installed in dist-packages
/usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-x86_64-linux-gnu.so
/usr/local/lib/python3.6/dist-packages/cv2.cpython-36m-x86_64-linux-gnu.so
## binary installed in site-packages
/usr/local/lib/python3.5/site-packages/cv2.cpython-35m-x86_64-linux-gnu.so
/usr/local/lib/python3.6/site-packages/cv2.cpython-36m-x86_64-linux-gnu.so

Double check the exact path on your machine before running the following commands

############ For Python 2 ############
cd ~/.virtualenvs/facecourse-py2/lib/python2.7/site-packages
ln -s /usr/local/lib/python2.7/dist-packages/cv2.so cv2.so

############ For Python 3 ############
cd ~/.virtualenvs/facecourse-py3/lib/python3.6/site-packages
ln -s /usr/local/lib/python3.6/dist-packages/cv2.cpython-36m-x86_64-linux-gnu.so cv2.so

Step 6: Test OpenCV3

We will test a red eye remover application written in OpenCV to test our C++ and Python installations. Download RedEyeRemover.zip and extract it into a folder.

Step 6.1: Test C++ code

Move inside extracted folder, compile and run.

# compile
# There are backticks ( ` ) around pkg-config command not single quotes
g++ -std=c++11 removeRedEyes.cpp `pkg-config --libs --cflags opencv` -o removeRedEyes
# run
./removeRedEyes

Step 6.2: Test Python code

Activate Python virtual environment

############ For Python 2 ############
workon facecourse-py2

############ For Python 3 ############
workon facecourse-py3

Quick Check

# open ipython (run this command on terminal)
ipython
# import cv2 and print version (run following commands in ipython)
import cv2
print cv2.__version__
# If OpenCV3 is installed correctly,
# above command should give output 3.3.1
# Press CTRL+D to exit ipython

Run RedEyeRemover demo

python removeRedEyes.py

Now you can exit from Python virtual environment.

deactivate

Whenever you are going to run Python scripts which use OpenCV you should activate the virtual environment we created, using workon command.



Comments

  1. Hi,

    Thanks for posting this. I am working through it, not done yet. I have one question or correction. In the following excerpt should “.bash_profile” be changed to “.bashrc” After all you just put new lines into .bashrc and the script can’t assume .bash_profile exists. Better to source the file that exist than the file that does not.

    *******Here is the context******

    # Install virtual environment
    sudo pip2 install virtualenv virtualenvwrapper
    sudo pip3 install virtualenv virtualenvwrapper
    echo “# Virtual Environment Wrapper” >> ~/.bashrc
    echo “source /usr/local/bin/virtualenvwrapper.sh” >> ~/.bashrc
    source ~/.bash_profile

    Reply

  2. Hi,

    Very good explanation !

    If I want to use only C++ ? What the libs that I don´t need to install ?
    My intention is minimize the required memory for a embedded application (like beaglebone, raspberry).

    Thanks

    Reply

    • If you only want to install for C++, you should follow steps: 2.1, 2.2, 4.1, 4.2, 5.1, 5.2, 5.3.

      Reply

  3. Hi I have QT 5 and QT creator 4 is already installed my system when I follow the steps above I have this error..

    Could not find a package configuration file provided by “Qt5Core” with any
    of the following names:

    Qt5CoreConfig.cmake
    qt5core-config.cmake

    Add the installation prefix of “Qt5Core” to CMAKE_PREFIX_PATH or set
    “Qt5Core_DIR” to a directory containing one of the above files. If
    “Qt5Core” provides a separate development package or SDK, be sure it has
    been installed.
    Call Stack (most recent call first):
    CMakeLists.txt:556 (include)

    CMake Warning at cmake/OpenCVFindLibsGUI.cmake:19 (find_package):
    By not providing “FindQt5Gui.cmake” in CMAKE_MODULE_PATH this project has
    asked CMake to find a package configuration file provided by “Qt5Gui”, but
    CMake did not find one.

    Could not find a package configuration file provided by “Qt5Gui” with any
    of the following names:

    Qt5GuiConfig.cmake
    qt5gui-config.cmake

    Add the installation prefix of “Qt5Gui” to CMAKE_PREFIX_PATH or set
    “Qt5Gui_DIR” to a directory containing one of the above files. If “Qt5Gui”
    provides a separate development package or SDK, be sure it has been
    installed.
    Call Stack (most recent call first):
    CMakeLists.txt:556 (include)

    and cmake says

    — Configuring incomplete, errors occurred!

    what can I do?

    Reply

    • You may not have qtbase5-dev and its dependencies installed or they are not in path. If you installed qt5 using apt-get, run sudo apt install qtbase5-dev. It will install the missing packages.

      Reply

  4. I am not seeing the cv.so in site-packages area.
    find /usr/local/lib/ -type f -name “cv2*.so”
    /usr/local/lib/python2.7/dist-packages/cv2.so
    /usr/local/lib/python3.4/dist-packages/cv2.cpython-34m.so

    The site-packages dir is empty.

    What could be wrong?

    I am installing this on Ubuntu 14.04

    Reply

    • Python modules are installed either in site-packages or dist-packages. So you can use /usr/local/lib/python2.7/dist-packages/cv2.so and /usr/local/lib/python3.4/dist-packages/cv2.cpython-34m.so paths as well to create a symlink.

      Reply

  5. Hi,
    I have been trying to install this on my ubuntu machine but no luck. facing dependancy issue. will you help me ?
    error —
    sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev
    Reading package lists… Done
    Building dependency tree
    Reading state information… Done
    Some packages could not be installed. This may mean that you have
    requested an impossible situation or if you are using the unstable
    distribution that some required packages have not yet been created
    or been moved out of Incoming.
    The following information may help to resolve the situation:

    The following packages have unmet dependencies:
    libavcodec-dev : Depends: libavutil-dev (= 7:2.8.6-1ubuntu2) but it is not going to be installed
    Depends: libswresample-dev (= 7:2.8.6-1ubuntu2) but it is not going to be installed
    libavformat-dev : Depends: libavformat-ffmpeg56 (= 7:2.8.6-1ubuntu2) but 7:2.8.11-0ubuntu0.16.04.1 is to be installed
    Depends: libavutil-dev (= 7:2.8.6-1ubuntu2) but it is not going to be installed
    Depends: libswresample-dev (= 7:2.8.6-1ubuntu2) but it is not going to be installed
    libswscale-dev : Depends: libavutil-dev (= 7:2.8.6-1ubuntu2) but it is not going to be installed
    Depends: libswscale-ffmpeg3 (= 7:2.8.6-1ubuntu2) but 7:2.8.11-0ubuntu0.16.04.1 is to be installed
    E: Unable to correct problems, you have held broken packages.

    Reply

    • This is a tricky situation.
      Run these commands
      sudo apt-get autoremove
      sudo apt-get clean
      sudo apt-get autoclean
      sudo apt-get update
      sudo apt-get upgrade

      If this doesn’t solve your problem, I suggest that you should take help from someone who knows about Ubuntu and has fixed this problem earlier. You will find a lot of solutions on internet to solve this, don’t try those solutions unless you exactly know what those commands do.

      Reply

  7. Hello,
    I’m a student, pursuing Masters degree in India. As a part of my curriculum, I’m working in a project that requires OpenCV library. I use Python 2.7.12 in Linux Environment Ubuntu 16.04. I was following the above mentioned steps and it worked fine till Step 5.3. At step 5.3 I faced an error. And I couldn’t solve it. I’ve attached the screenshots of the error message. Please help me. Thank you.
    Screenshot_1: https://uploads.disquscdn.com/images/c026873e202f5c32becb93a9428577693761142a7399ab5ffcca7ff490b55964.png
    Screenshot_2: https://uploads.disquscdn.com/images/8ca270455b81e218a0bbf4b9fbe0215552f9a5fccd55c87665a2f447c28514fb.png

    Reply

  9. Hi! I’, trying to install OpenCV 3.3.0 but I get an error while make-ing:
    “CMake Error at cuda_compile_generated_gpu_mat.cu.o.cmake:266”

    I’ve got CUDA 8 installed, its path set in PATH variable accordingly.
    I googled this error but I can’t find a working solution. I see quite a lot of people solved it by adding “set(NVCC_FLAGS_EXTRA ${NVCC_FLAGS_EXTRA} -D_FORCE_INLINES)” to openvc/cmake/OpenCVDetectCUDA.cmake but the patch is already there.

    The only difference I see from this tutorial is that I’m using Anaconda environments instead of virtualenv but I don’t expect that to be the problem.
    One doubt: I have already installed opencv2 using conda, to be used in Python 3. Maybe some conflict?

    Any suggestion?

    Reply

    • i also had issues building with anaconda in the path, then i removed it from env, and then it built successfully in a new terminal without anaconda in the env.

      Reply

  10. Hi,

    I’m having a problem in the step 3.

    ############ For Python 2 ############
    # create virtual environment
    mkvirtualenv facecourse-py2 -p python2

    Output:

    Running virtualenv with interpreter /home/user/anaconda2/bin/python2
    New python executable in /home/user/.virtualenvs/facecourse-py2/bin/python2
    Not overwriting existing python script /home/user/.virtualenvs/facecourse-py2/bin/python (you must use /home/user/.virtualenvs/facecourse-py2/bin/python2)
    Installing setuptools, pip, wheel…
    Complete output from command /home/user/.virtua…urse-py2/bin/python2 – setuptools pip wheel:
    Exception:
    Traceback (most recent call last):
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/basecommand.py”, line 215, in main
    status = self.run(options, args)
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/commands/install.py”, line 272, in run
    with self._build_session(options) as session:
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/basecommand.py”, line 72, in _build_session
    insecure_hosts=options.trusted_hosts,
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/download.py”, line 329, in __init__
    self.headers[“User-Agent”] = user_agent()
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/download.py”, line 69, in user_agent
    “python”: platform.python_version(),
    File “/home/user/anaconda2/lib/python2.7/platform.py”, line 1470, in python_version
    return _sys_version()[1]
    File “/home/user/anaconda2/lib/python2.7/platform.py”, line 1422, in _sys_version
    repr(sys_version))
    ValueError: failed to parse CPython sys.version: ‘2.7.12 (default, Nov 19 2016, 06:48:10) n[GCC 5.4.0 20160609]’
    Traceback (most recent call last):
    File “”, line 23, in
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/__init__.py”, line 233, in main
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/basecommand.py”, line 251, in main
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/basecommand.py”, line 72, in _build_session
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/download.py”, line 329, in __init__
    File “/usr/local/lib/python3.5/dist-packages/virtualenv_support/pip-9.0.1-py2.py3-none-any.whl/pip/download.py”, line 69, in user_agent
    File “/home/user/anaconda2/lib/python2.7/platform.py”, line 1470, in python_version
    return _sys_version()[1]
    File “/home/user/anaconda2/lib/python2.7/platform.py”, line 1422, in _sys_version
    repr(sys_version))
    ValueError: failed to parse CPython sys.version: ‘2.7.12 (default, Nov 19 2016, 06:48:10) n[GCC 5.4.0 20160609]’
    —————————————-
    …Installing setuptools, pip, wheel…done.
    Traceback (most recent call last):
    File “/usr/local/lib/python3.5/dist-packages/virtualenv.py”, line 2328, in
    main()
    File “/usr/local/lib/python3.5/dist-packages/virtualenv.py”, line 713, in main
    symlink=options.symlink)
    File “/usr/local/lib/python3.5/dist-packages/virtualenv.py”, line 945, in create_environment
    download=download,
    File “/usr/local/lib/python3.5/dist-packages/virtualenv.py”, line 901, in install_wheel
    call_subprocess(cmd, show_stdout=False, extra_env=env, stdin=SCRIPT)
    File “/usr/local/lib/python3.5/dist-packages/virtualenv.py”, line 797, in call_subprocess
    % (cmd_desc, proc.returncode))
    OSError: Command /home/user/.virtua…urse-py2/bin/python2 – setuptools pip wheel failed with error code 1

    Thank you a lot,

    and sorry if the question is too obvious.

    Reply

      • Iam actually using Ubuntu 17.04 and at step 5.2 ,I’m getting an error.
        Error(CMake Error: The source directory “/home/manikanta/opencv” does not appear to contain CMakeLists.txt.
        Specify –help for usage, or press the help button on the CMake GUI.)

        Please help me with this.

        Reply

  13. Hello, Please help, I’m getting this error when I run ‘import cv2’ in ipython. (Step 6.2)

    —————————————————————————
    ImportError Traceback (most recent call last)
    in ()
    —-> 1 import cv2

    ImportError: /opt/ros/kinetic/lib/python2.7/dist-packages/cv2.so: undefined symbol: PyCObject_Type
    ——————————————————————————-
    I have followed the procedure for Python 3.6 in this tutorial, but python 2.7 might have already been installed when i was working on earlier project. What do I do now? Should I start the procedure all over again? But if that is so, then what uninstallation commands do I have to run?

    Reply

    • Or let me know how to uninstall all the installed packages so that I can start from scratch again. I’ll try installing both simultaneously this time.

      Reply

      • Hey,
        I ran the step 5.4 for Python 2.7 and it worked. But “import cv2” (Step 6.2) only works on Python 2.7 now, I don’t know how to change the default setting and set it up with Python 3 although.
        For your problem, I think running Step 5.4 properly again should work.

        Reply

  14. This tutorial was very useful for me, but seems a luxury configuration:

    * gfortran is not necessary for ocv (it is necessary for R, a statistical environment … and for me)

    * yasm is not necessary.

    *checkinstall is not necessary at all (except if one wants to make one’s build a Debian package : this might be useful if one has a lot of PCs, with about the same hardware and does not want to recompile on each and every PC )

    * if protobuf is not install, opencv provides a substitute; same thing happens with jasper (BTW : does libjasper-dev exist on every ubuntu ; my virtual ubuntu 17 could not apt-get it … libopencorexxxs do not seem necessary, either..

    Reply

  15. But why using a virtual environment? Can’t we install this to just use normally like other packages?

    Reply

  16. I cannot get the RemoveRedEyes example to compile. I get the following error:

    /usr/bin/ld: warning: libIlmImf.so.6, needed by /usr/local/lib/libopencv_imgcodecs.so, not found (try using -rpath or -rpath-link)
    /usr/bin/ld: warning: libHalf.so.6, needed by /usr/local/lib/libopencv_imgcodecs.so, not found (try using -rpath or -rpath-link)

    I did a search on my system for these library files and found:

    libIlmImf-2_2.so.22 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libIlmImf-2_2.so.22
    libHalf.so.12 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libHalf.so.12

    I tried linking these libraries with the -L flag and get:

    /usr/bin/ld: cannot find -libIlmImf
    /usr/bin/ld: cannot find -libHalf

    What should I do now? I’m kind of lost…

    Reply

  17. This tutorial works great.
    The only problem is I don’t get the prompt back after running the example programs.

    Reply

    • I am curious about this myself. I didn’t do it but it still worked. Maybe on some distributions it won’t compile otherwise.

      Reply

  19. works like charm….Really helped to install C++, Python 2.7, 3.5 OpenCV in Ubuntu 16.04 in one go.

    Reply

  20. Hello, Thanks for Tuto !
    To the step

    Step 6.2: Test Python code
    The test work for python 2 but not for python 3, how can i fix that ? cv2 is not found for python 3 on ipyhon.
    Thanks in advance !

    Reply

  22. Hi I am using ubuntu 16.04, where i have installed Anaconda3 and by creating conda env i have installed tensorflow,cuda,cuDNN and openCV 3.3.0 (using pip).

    Then i import cv2 in python 3.5 most of the things works fine. but cv2.VideoCapture(0) returns false.

    here is my code: (to capture video from webcam of my laptop)
    ”
    import numpy as np
    import cv2

    cap = cv2.VideoCapture(0)
    fourcc = cv2.VideoWriter_fourcc(*’XVID’)
    out = cv2.VideoWriter(‘output.avi’,fourcc, 20.0, (640,480))

    while(True):
    ret, frame = cap.read()
    print(ret)
    cv2.imshow(‘frame’,frame)
    if cv2.waitKey(1) & 0xFF == ord(‘q’):
    break

    cap.release()
    cv2.destroyAllWindows()
    ”

    And here is error i am getting.
    https://uploads.disquscdn.com/images/430b8fb6beeafd6bd3a964159fa1c27bf84a54c9fb0fa48aaa71e8ecb215e776.png

    if anyone could solve this problem it will be very very appreciated.

    Reply

  23. don’t know why I’m getting this error help me to fix this please (I don’t have any GPU instlled in my computer )
    In file included from /home/nikhil/opencv/modules/stitching/include/opencv2/stitching.hpp:49:0,
    from /home/nikhil/opencv/modules/stitching/src/precomp.hpp:59,
    from /home/nikhil/opencv/build/modules/stitching/opencv_stitching_pch_dephelp.cxx:1:
    /home/nikhil/opencv/modules/stitching/include/opencv2/stitching/detail/matchers.hpp:52:42: fatal error: opencv2/xfeatures2d/cuda.hpp: No such file or directory
    compilation terminated.
    modules/stitching/CMakeFiles/opencv_stitching_pch_dephelp.dir/build.make:62: recipe for target ‘modules/stitching/CMakeFiles/opencv_stitching_pch_dephelp.dir/opencv_stitching_pch_dephelp.cxx.o’ failed
    make[2]: *** [modules/stitching/CMakeFiles/opencv_stitching_pch_dephelp.dir/opencv_stitching_pch_dephelp.cxx.o] Error 1
    CMakeFiles/Makefile2:20627: recipe for target ‘modules/stitching/CMakeFiles/opencv_stitching_pch_dephelp.dir/all’ failed
    make[1]: *** [modules/stitching/CMakeFiles/opencv_stitching_pch_dephelp.dir/all] Error 2
    make[1]: *** Waiting for unfinished jobs….
    [ 21%] Linking CXX static library ../../lib/libopencv_test_optflow_pch_dephelp.a
    [ 21%] Built target opencv_test_optflow_pch_dephelp
    [ 21%] Linking CXX static library ../../lib/libopencv_optflow_pch_dephelp.a
    [ 21%] Built target opencv_optflow_pch_dephelp
    [ 21%] Linking CXX static library ../../lib/libopencv_sfm_pch_dephelp.a
    [ 21%] Built target opencv_sfm_pch_dephelp
    Makefile:162: recipe for target ‘all’ failed
    make: *** [all] Error 2

    Reply

  26. Hey, Thank you for great tutorial. I have one problem. I completed all the steps and I also have “cv2” files available in my build folder but when I import cv2, it again gives me same error that no module named cv2. Check screenshots for reference.

    https://uploads.disquscdn.com/images/faedde628d001933e6c4db7a6c2371443e06b7997e8f4a63da3a270b816ac10b.png https://uploads.disquscdn.com/images/8c3f005471fcc0f54f5bb96d5726b66503fd582591ce0e12a2244dec9049e6ac.png

    Reply

      • Hello, my raspberry just finished compiling and installing.

        When I try to import cv2 in python3 I get this:
        >>> import cv2
        Illegal instruction

        and I have this in he build directory:
        grep -A99 Python version_string.tmp
        ” Python 3:n”
        ” Interpreter: /usr/bin/python3 (ver 3.5.3)n”
        …
        ” Python (for build): /usr/bin/python2.7n”

        Do you have any suggestion, if I did anything wrong?

        Reply

        • Before you import cv2. Did you install python_opencv?
          It is looks like you installed the module for python 2, but are trying to run it from python 3
          pip3 install opencv-python

          Reply

          • My other comment is waiting for approval, but in the meantime I found something (which is sad story for me, but): I had to add the deb-multimedia repository to install some prerequisites… and I read somewhere it’s not intended to work with arm6 (which my pi 1 B based on)

          • OIC. U r using rapsberry pi 1. But not rpi 3. The rpi 1B is 32-bit. R u using Debian Stretch? .

          • It’s a Raspbian Stretch.
            I have a banana pi m2 berry too with an Ubuntu mate image but there I faced issues earlier which seems harder to solve so I gave up.
            Now I’ll try the banana again with Raspbian, at least if the compile works it won1t take more than 24 hours 😀

          • Right, but there I face other issues, based on similar error messages discussed on some forums I guess the QT5 version available from the repo is too old (). Tried with -j1 but it didn’t help. It’s been told to be fixed in latest version of openCV but maybe that works properly with QT5.9 which has no available build for arm (at least I didn’t find and I don’t really want to compile everything)

          • That’s shouldn’t be a deal breaker. I just need to know how to make sure python 3 is not summoned but python 2.7 is. Any idea? Since you mentioned the user was trying to run it from Python 3

          • Python 2 is differentiated from Python 3. The Python 2 will be fading out in 2019. The commands is not the same as Python 3.

          • Python 2 is differentiated from Python 3. The Python 2 will be fading out in 2019. The commands is not the same as Python 3.

          • hey Nishanth I m having same problem could you tell me how you solved it??

          • Hey – I wasnt able to get helpful inputs to solve the above problem. Since its a conflict, and after a couple of hours of trying unsuccessfully, I got desperate, I proceeded to bravely delete all python installations except python 2.7 from my system by rm -rf the library folders. I WOULDNT recommend the rm -rf way at all but sometimes i feel its the only way to effectively deal with residual installs and it worked for me.

            Next, I deleted the ‘build’ folder in order to restart this installation and switched to using Adrian’s install method from:
            https://www.pyimagesearch.com/2016/10/24/ubuntu-16-04-how-to-install-opencv/

            I faced stdin issues and HDF5 not available issues (after 70%-80% of compiling done) which I am guessing you might too post solving the python conflict. If you do please add the last two lines mentioned below:

            cmake -D CMAKE_BUILD_TYPE=RELEASE
            -D CMAKE_INSTALL_PREFIX=/usr/local
            -D INSTALL_PYTHON_EXAMPLES=ON
            -D INSTALL_C_EXAMPLES=OFF
            -D OPENCV_EXTRA_MODULES_PATH=~/opencv_contrib-3.1.0/modules
            -D PYTHON_EXECUTABLE=~/.virtualenvs/cv/bin/python
            -D BUILD_EXAMPLES=ON
            -D ENABLE_PRECOMPILED_HEADERS=OFF
            -D WITH_HDF5=OFF ..

            second last line: solves the stdin error
            last line: solves the hdf5 not found error.
            Also dont forget to run the above command with the ‘..’ at the last line.

          • Hey – I wasnt able to get helpful inputs to solve the above problem. Since its a conflict, and after a couple of hours of trying unsuccessfully, I got desperate, I proceeded to bravely delete all python installations except python 2.7 from my system by rm -rf the library folders. I WOULDNT recommend the rm -rf way at all but sometimes i feel its the only way to effectively deal with residual installs and it worked for me.

            Next, I deleted the ‘build’ folder in order to restart this installation and switched to using Adrian’s install method from:
            https://www.pyimagesearch.com/2016/10/24/ubuntu-16-04-how-to-install-opencv/

            I faced stdin issues and HDF5 not available issues (after 70%-80% of compiling done) which I am guessing you might too post solving the conflict. If you do please follow these steps:

            cmake -D CMAKE_BUILD_TYPE=RELEASE
            -D CMAKE_INSTALL_PREFIX=/usr/local
            -D INSTALL_PYTHON_EXAMPLES=ON
            -D INSTALL_C_EXAMPLES=OFF
            -D OPENCV_EXTRA_MODULES_PATH=~/opencv_contrib-3.1.0/modules
            -D PYTHON_EXECUTABLE=~/.virtualenvs/cv/bin/python
            -D BUILD_EXAMPLES=ON
            -D ENABLE_PRECOMPILED_HEADERS=OFF
            -D WITH_HDF5=OFF ..

            second last line: solves the stdin error
            last line: solves the hdf5 not found error.
            Also dont forget to run the above command with the ‘..’ at the last line.

  27. 4.12.2017
    A well written tutorial. I would like to see a Debian Stretch version
    so I could try it on a Raspberry Pi 3.
    You flash Advert is annoying – one must reload the page after it starts.

    Reply

  29. Hi, Thanks for article. I’m using Ubuntu 14.04 and I followed all the steps and installed OpenCV 3.

    I get a lot of error when compiling cpp example. Given below is the log (trimmed a lot of errors for easy readability). I was able to run removeRedEyes.py successfully.

    Given below is the log (appologies for the huge log). Appreciate any pointers on what could be going wrong.

    [email protected]:~/Downloads/RedEyeRemover$ g++-4.8 -std=c++11 removeRedEyes.cpp `pkg-config –libs –cflags opencv` -o removeRedEyes
    /usr/local/lib/libopencv_imgcodecs.a(grfmt_jpeg.cpp.o): In function `cv::my_jpeg_load_dht(jpeg_decompress_struct*, unsigned char*, JHUFF_TBL**, JHUFF_TBL**) [clone .constprop.40]’:
    grfmt_jpeg.cpp:(.text.unlikely._ZN2cvL16my_jpeg_load_dhtEP22jpeg_decompress_structPhPP9JHUFF_TBLS5_.constprop.40+0x11e): undefined reference to `jpeg_alloc_huff_table’
    /usr/local/lib/libopencv_imgcodecs.a(grfmt_jpeg.cpp.o): In function `cv::JpegEncoder::write(cv::Mat const&, std::vector<int, std::allocator > const&)’:
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0xd8): undefined reference to `jpeg_CreateCompress’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0xe5): undefined reference to `jpeg_std_error’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0x2b3): undefined reference to `jpeg_set_defaults’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0x2cf): undefined reference to `jpeg_set_quality’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0x2fc): undefined reference to `jpeg_quality_scaling’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0x30a): undefined reference to `jpeg_quality_scaling’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0x34c): undefined reference to `jpeg_default_qtables’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0x35e): undefined reference to `jpeg_start_compress’
    grfmt_jpeg.cpp:(.text._ZN2cv11JpegEncoder5writeERKNS_3MatERKSt6vectorIiSaIiEE+0x3e2):

    …..
    …..
    ….

    (.text._ZL42OPENCL_FN_clEnqueueNDRangeKernel_switch_fnP17_cl_command_queueP10_cl_kerneljPKmS4_S4_jPKP9_cl_eventPS6_+0x18e): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL42OPENCL_FN_clEnqueueNDRangeKernel_switch_fnP17_cl_command_queueP10_cl_kerneljPKmS4_S4_jPKP9_cl_eventPS6_+0x262): undefined reference to `dlclose’
    /usr/local/lib/libopencv_core.a(opencl_core.cpp.o): In function `OPENCL_FN_clEnqueueFillBuffer_switch_fn(_cl_command_queue*, _cl_mem*, void const*, unsigned long, unsigned long, unsigned long, unsigned int, _cl_event* const*, _cl_event**)’:
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueFillBuffer_switch_fnP17_cl_command_queueP7_cl_memPKvmmmjPKP9_cl_eventPS6_+0x34): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueFillBuffer_switch_fnP17_cl_command_queueP7_cl_memPKvmmmjPKP9_cl_eventPS6_+0x175): undefined reference to `dlopen’
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueFillBuffer_switch_fnP17_cl_command_queueP7_cl_memPKvmmmjPKP9_cl_eventPS6_+0x18e): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueFillBuffer_switch_fnP17_cl_command_queueP7_cl_memPKvmmmjPKP9_cl_eventPS6_+0x262): undefined reference to `dlclose’
    /usr/local/lib/libopencv_core.a(opencl_core.cpp.o): In function `OPENCL_FN_clEnqueueCopyImage_switch_fn(_cl_command_queue*, _cl_mem*, _cl_mem*, unsigned long const*, unsigned long const*, unsigned long const*, unsigned int, _cl_event* const*, _cl_event**)’:
    opencl_core.cpp:(.text._ZL38OPENCL_FN_clEnqueueCopyImage_switch_fnP17_cl_command_queueP7_cl_memS2_PKmS4_S4_jPKP9_cl_eventPS6_+0x34): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL38OPENCL_FN_clEnqueueCopyImage_switch_fnP17_cl_command_queueP7_cl_memS2_PKmS4_S4_jPKP9_cl_eventPS6_+0x175): undefined reference to `dlopen’
    opencl_core.cpp:(.text._ZL38OPENCL_FN_clEnqueueCopyImage_switch_fnP17_cl_command_queueP7_cl_memS2_PKmS4_S4_jPKP9_cl_eventPS6_+0x18e): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL38OPENCL_FN_clEnqueueCopyImage_switch_fnP17_cl_command_queueP7_cl_memS2_PKmS4_S4_jPKP9_cl_eventPS6_+0x262): undefined reference to `dlclose’
    /usr/local/lib/libopencv_core.a(opencl_core.cpp.o): In function `OPENCL_FN_clEnqueueCopyBuffer_switch_fn(_cl_command_queue*, _cl_mem*, _cl_mem*, unsigned long, unsigned long, unsigned long, unsigned int, _cl_event* const*, _cl_event**)’:
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueCopyBuffer_switch_fnP17_cl_command_queueP7_cl_memS2_mmmjPKP9_cl_eventPS4_+0x34): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueCopyBuffer_switch_fnP17_cl_command_queueP7_cl_memS2_mmmjPKP9_cl_eventPS4_+0x175): undefined reference to `dlopen’
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueCopyBuffer_switch_fnP17_cl_command_queueP7_cl_memS2_mmmjPKP9_cl_eventPS4_+0x18e): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL39OPENCL_FN_clEnqueueCopyBuffer_switch_fnP17_cl_command_queueP7_cl_memS2_mmmjPKP9_cl_eventPS4_+0x262): undefined reference to `dlclose’
    /usr/local/lib/libopencv_core.a(opencl_core.cpp.o): In function `OPENCL_FN_clLinkProgram_switch_fn(_cl_context*, unsigned int, _cl_device_id* const*, char const*, unsigned int, _cl_program* const*, void (*)(_cl_program*, void*), void*, int*)’:
    opencl_core.cpp:(.text._ZL33OPENCL_FN_clLinkProgram_switch_fnP11_cl_contextjPKP13_cl_device_idPKcjPKP11_cl_programPFvS8_PvESB_Pi+0x33): undefined reference to `dlsym’
    opencl_core.cpp:(.text._ZL33OPENCL_FN_clLinkProgram_switch_fnP11_cl_contextjPKP13_cl_device_idPKcjPKP11_cl_programPFvS8_PvESB_Pi+0x175): undefined reference to `dlopen’
    opencl_core.cpp:

    …
    …
    …

    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal12magnitude32fEPKfS2_Pfi+0xcc): undefined reference to `ippicvsMagnitude_32f’
    /usr/local/lib/libopencv_core.a(mathfuncs_core.dispatch.cpp.o): In function `cv::hal::magnitude64f(double const*, double const*, double*, int)’:
    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal12magnitude64fEPKdS2_Pdi+0xcc): undefined reference to `ippicvsMagnitude_64f’
    /usr/local/lib/libopencv_core.a(mathfuncs_core.dispatch.cpp.o): In function `cv::hal::invSqrt32f(float const*, float*, int)’:
    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal10invSqrt32fEPKfPfi+0x4e): undefined reference to `ippicvsInvSqrt_32f_A21′
    /usr/local/lib/libopencv_core.a(mathfuncs_core.dispatch.cpp.o): In function `cv::hal::invSqrt64f(double const*, double*, int)’:
    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal10invSqrt64fEPKdPdi+0x4e): undefined reference to `ippicvsInvSqrt_64f_A50′
    /usr/local/lib/libopencv_core.a(mathfuncs_core.dispatch.cpp.o): In function `cv::hal::exp32f(float const*, float*, int)’:
    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal6exp32fEPKfPfi+0x4e): undefined reference to `ippicvsExp_32f_A21′
    /usr/local/lib/libopencv_core.a(mathfuncs_core.dispatch.cpp.o): In function `cv::hal::exp64f(double const*, double*, int)’:
    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal6exp64fEPKdPdi+0x4e): undefined reference to `ippicvsExp_64f_A50′
    /usr/local/lib/libopencv_core.a(mathfuncs_core.dispatch.cpp.o): In function `cv::hal::log32f(float const*, float*, int)’:
    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal6log32fEPKfPfi+0x4e): undefined reference to `ippicvsLn_32f_A21′
    /usr/local/lib/libopencv_core.a(mathfuncs_core.dispatch.cpp.o): In function `cv::hal::log64f(double const*, double*, int)’:
    mathfuncs_core.dispatch.cpp:(.text._ZN2cv3hal6log64fEPKdPdi+0x4e): undefined reference to `ippicvsLn_64f_A50′

    Reply

  30. Hello! Thanks for the easy to follow tutorial. However, I am facing an issue with installation. The system I am using is Ubuntu 17.10 with the following kernel details:
    “Linux aditya 4.13.0-19-generic #22-Ubuntu SMP Mon Dec 4 11:58:07 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux”.

    The g++ version that I am using as default with the Ubuntu is “g++ (Ubuntu 7.2.0-8ubuntu3) 7.2.0
    Copyright (C) 2017 Free Software Foundation, Inc.”

    I have nvidia GPU and CUDA 9.0. The samples given with cuda are running nicely. However, compilation (“make”) of opencv shows that compilation is not possible :
    ”
    [ 10%] Building NVCC (Device) object modules/core/CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_gpu_mat.cu.o
    nvcc warning : The ‘compute_20’, ‘sm_20’, and ‘sm_21’ architectures are deprecated, and may be removed in a future release (Use -Wno-deprecated-gpu-targets to suppress warning).
    In file included from /usr/include/cuda_runtime.h:78:0,
    from :0:
    /usr/include/host_config.h:119:2: error: #error — unsupported GNU version! gcc versions later than 5 are not supported!
    #error — unsupported GNU version! gcc versions later than 5 are not supported!
    ^~~~~
    CMake Error at cuda_compile_generated_gpu_mat.cu.o.cmake:208 (message):
    Error generating
    /home/vega/openCV_SOURCE/opencv/build/modules/core/CMakeFiles/cuda_compile.dir/src/cuda/./cuda_compile_generated_gpu_mat.cu.o

    modules/core/CMakeFiles/opencv_core.dir/build.make:63: recipe for target ‘modules/core/CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_gpu_mat.cu.o’ failed
    make[2]: *** [modules/core/CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_gpu_mat.cu.o] Error 1
    CMakeFiles/Makefile2:2718: recipe for target ‘modules/core/CMakeFiles/opencv_core.dir/all’ failed
    make[1]: *** [modules/core/CMakeFiles/opencv_core.dir/all] Error 2
    Makefile:162: recipe for target ‘all’ failed
    make: *** [all] Error 2
    ”

    Please help me to proceed with compilation.
    Thank You.
    Abhijit

    Reply

  32. Hello, I meet some problems with the video. Here is the code below and it does work except the output is v4l2: pixel format of incoming image is unsupported by OpenCV. Is there any solution?

    #include “opencv2/opencv.hpp”

    using namespace cv;

    int main(int, char**)
    {
    VideoCapture cap(0); // open the default camera
    if(!cap.isOpened()) // check if we succeeded
    return -1;

    Mat edges;
    namedWindow(“edges”,1);
    for(;;)
    {
    Mat frame;
    cap >> frame; // get a new frame from camera
    cvtColor(frame, edges, COLOR_BGR2GRAY);
    GaussianBlur(edges, edges, Size(7,7), 1.5, 1.5);
    Canny(edges, edges, 0, 30, 3);
    imshow(“edges”, edges);
    if(waitKey(30) >= 0) break;
    }
    // the camera will be deinitialized automatically in VideoCapture destructor
    return 0;
    }

    Reply

  35. I’m installing opencv on raspberry pi 2 model B. “make -j(nproc)” gets stuck at certain percentage (27%). I rebooted it and run the process again at it got stuck at same spot. (At the time of writing), I’m running it with only “make”. It’s too slow. Can you provide a solution or direction?

    Reply

    • There is no obvious solution, as RAM is too small to have it compiled.

      Running with “only” make maybe sufficient (only one process is using RAM) and you can have your RPi compiling during night.

      If this is not enough (RAM+swap too small) you can have a greater swap file (on an external disk, minimizing risks of SD card being worn) the following way:

      * remove built in swap (on the SD card : 100 M are used, which is not enough)

      sudo swapoff -a

      prepare a new swap file (ca 1G), on an external disk

      dd if=/dev/zero of=/path/to/new/swap/SWP bs=1k count=800k

      (form memory)

      mkswap /path/to/new/swap/SWP

      These former 2 commands are used only once, at swap file generation

      The following one is used only when one needs swap file

      sudo swapon /path/to/new/swap/SWP
      then, launch compilation (beware it may be very long)

      Other solution is to have a look at dphys (wraps swapon/swapoff) but the idea is the same.

      Reply

  37. Hi,

    I’m getting the following error when I’m trying to use opencv for a different application, kindly help:

    undefined reference to `cv::VideoCapture::retrieve(cv::_OutputArray const&, int)’
    CMakeFiles/vbtracker-cam.dir/TestStandalone.cpp.o: In function `Main::Main()’:

    Reply

  38. Nice, except that I kept getting the error:

    ./removeRedEyes: error while loading shared libraries: libopencv_highgui.so.3.4: cannot open shared object file: No such file or directory

    After some searching I found out that OpenCV libraries got installed here: /usr/local/lib/x86_64-linux-gnu/

    so I had to update this command with the actual library path:

    sudo sh -c ‘echo “/usr/local/lib/x86_64-linux-gnu” >> /etc/ld.so.conf.d/opencv.conf’

    Now it is working! Thanks!

    Reply

  39. I have done all the steps and everything runs fine but at the end when I run find /usr/local/lib/ -type f -name “cv2*.so”
    Nothing is printed out and I am unable to import cv2 or opencv2 in python3. I have tried repeating the whole installation steps but same result again.
    I guess the problem is for those people who don’t want to use virtual environment. Can u please give this liberty not to install virtual environment and plz no anaconda suggestions (don’t want to install a package (anaconda) to run another package (python)) ?

    Reply

      • I skipped it but the problem was there that no cv2 file was appearing in dist packages. so after another attempt from the start and using git clone https://github.com/opencv/opencv.git with specific destination directory worked for me. sounds weird but worked on my system.
        I’d recommend installing opencv before tensorflow unlike me who did the opposite. I don’t know what confict that might cause but since we change PATH and LD_LIBRARY_PATH settings during tensorflow installation in ubuntu so that could also be the reason.

        Reply

          • i am using python3 and the opencv version installed is 3.3.1 as it was suggested in the tutorial. do you suggest to use command pip3 to update to the newer one ? and if so what other changes ?

          • OpenCV 3.3.1 is outdated. The OpenCV release is 3.4.1, Can you install 3.4.1?
            BTW, change this 3.3.1 to 3.4.1
            Yes you can do pip3 too,

          • so if i use pip3 install opencv-python, would I need to re-set the PATH settings?
            I am new in Ubuntu and python so not sure if this step would need further tweaking…
            I appreciate your assistance in this matter.

  43. I have followed the steps ( omited python libraries and examples and openGL, i want just c++ ) but i got error at 84%
    [ 84%] Built target opencv_videostab
    Makefile:160: recipe for target ‘all’ failed
    make: *** [all] Error 2

    What is happening? How can i fix this?

    Reply

  44. Hi, I think there is an error in line 20.
    Maybe you mean libfaad-dev (with ‘d’ instead of ‘c’).

    Thanks!

    Reply

  45. hey am following the above instructions, till Step 5.2 i am able to it from there onwards i got stuck
    I think in 5.3 some details are missing .

    Reply

  46. Just in case you had problems with libtiff on Ubuntu 17.10 OpenCV 4.1 adding
    -D BUILD_TIFF=ON to cmake will do the trick

    cmake -D CMAKE_BUILD_TYPE=RELEASE
    -D CMAKE_INSTALL_PREFIX=/usr/local
    -D INSTALL_C_EXAMPLES=ON
    -D INSTALL_PYTHON_EXAMPLES=ON
    -D WITH_TBB=ON
    -D WITH_V4L=ON
    -D WITH_QT=ON
    -D WITH_OPENGL=ON
    -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules
    -D BUILD_TIFF=ON
    -D BUILD_EXAMPLES=ON ..

    http://answers.opencv.org/question/35642/libtiff_40-link-errors/

    Reply

  47. Just in case you had problems with libtiff on Ubuntu 17.10 OpenCV 4.1 adding
    -D BUILD_TIFF=ON to cmake will do the trick

    http://answers.opencv.org/question/35642/libtiff_40-link-errors/

    cmake -D CMAKE_BUILD_TYPE=RELEASE
    -D CMAKE_INSTALL_PREFIX=/usr/local
    -D INSTALL_C_EXAMPLES=ON
    -D INSTALL_PYTHON_EXAMPLES=ON
    -D WITH_TBB=ON
    -D WITH_V4L=ON
    -D WITH_QT=ON
    -D WITH_OPENGL=ON
    -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules
    -D WITH_TIFF=ON
    -D BUILD_TIFF=ON
    -D BUILD_EXAMPLES=ON ..

    Reply

  49. I was following the installation guideline.After I installed,I was checking for the C++ outup and got this error

    removeRedEyes.cpp: In function ‘int main(int, char**)’:
    removeRedEyes.cpp:30:38: error: ‘CV_LOAD_IMAGE_COLOR’ was not declared in this scope
    Mat img = imread(“red_eyes2.jpg”,CV_LOAD_IMAGE_COLOR);
    ^~~~~~~~~~~~~~~~~~~
    removeRedEyes.cpp:30:38: note: suggested alternative: ‘CV_HAL_DFT_STAGE_COLS’
    Mat img = imread(“red_eyes2.jpg”,CV_LOAD_IMAGE_COLOR);
    ^~~~~~~~~~~~~~~~~~~
    CV_HAL_DFT_STAGE_COLS
    I am using Ubuntu 18.04 but my python version works well.If anybody could help me to sought this out.

    Reply

  53. When trying to install virtual environment on pip I’m getting an error message saying ‘ The directory ‘/home/kshama/.cache/pip/http’ or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo’s -H flag.
    The directory ‘/home/kshama/.cache/pip’ or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo’s -H flag.’ How to enable cache for the parent directory ? Someone help please

    Reply

  58. This is the only working tutorial for OpenCV + Ubuntu 16.04 that I’ve found!

    Alas, I would like to use an IDE to code. Is there a tutorial for setting up OpenCV with any decent IDE?

    Reply

  59. I try to import the the cv2 library, like in the examples, but it returns the error message No module named ‘cv2’. Any idea what can i have done wrong? Thanks.

    Reply

  60. hi… during installation of opencv in ubuntu….

    cmake -D CMAKE_BUILD_TYPE=RELEASE
    -D CMAKE_INSTALL_PREFIX=/usr/local
    -D INSTALL_C_EXAMPLES=ON
    -D INSTALL_PYTHON_EXAMPLES=ON
    -D WITH_TBB=ON
    -D WITH_V4L=ON
    -D WITH_QT=ON
    -D WITH_OPENGL=ON
    -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules
    -D BUILD_EXAMPLES=ON ..

    after executing above step following issue is occur…

    Configuring incomplete, errors occurred!
    See also “/home/user/opencv/build/CMakeFiles/CMakeOutput.log”.
    See also “/home/user/opencv/build/CMakeFiles/CMakeError.log”.

    plz help….
    thanks….

    Reply

  61. Hi, I’m using Ubuntu for windows and and having an error when running the python script:
    QXcbConnection: Could not connect to display
    Anybody have any ideas?

    Reply

  63. When I run workon facecourse-py3, I get the error, virtualenvwrapper.user_scripts could not run “/home/sverma/.virtualenvs/preactivate”: [Errno 8] Exec format error
    virtualenvwrapper.user_scripts could not run “/home/sverma/.virtualenvs/facecourse-py3/bin/preactivate”: [Errno 8] Exec format error

    Reply

  64. I got “nproc” as 4. Then I tried the “make -j4” which ran till 64% and gave errors.

    collect2: error: ld returned 1 exit status
    modules/viz/CMakeFiles/opencv_test_viz.dir/build.make:238: recipe for target ‘bin/opencv_test_viz’ failed
    make[2]: *** [bin/opencv_test_viz] Error 1
    CMakeFiles/Makefile2:5804: recipe for target ‘modules/viz/CMakeFiles/opencv_test_viz.dir/all’ failed
    make[1]: *** [modules/viz/CMakeFiles/opencv_test_viz.dir/all] Error 2
    make[1]: *** Waiting for unfinished jobs….
    [ 64%] Built target example_datasets_ir_affine
    [ 64%] Built target example_datasets_or_mnist
    [ 64%] Built target example_datasets_tr_svt
    Makefile:160: recipe for target ‘all’ failed
    make: *** [all] Error 2

    Reply

  65. Hi, I have problem with step 5.2, please see the follow codes:

    ========================================
    Configuring incomplete, errors occurred!
    See also “/home/steven/opencv/build/CMakeFiles/CMakeOutput.log”.
    See also “/home/steven/opencv/build/CMakeFiles/CMakeError.log”.
    ========================================

    Could you please help me?

    Thank you very much!
    Steven

    https://uploads.disquscdn.com/images/54113cb7488a7db6d0075c3fe69739904c8f7b1bd5023537276c1352b5c7f5b9.png

    Reply

  67. I am facing problem with linking, my program is not compiling and giving the following error,
    Just invested my 3-4 hrs but no success, please help.

    All the steps were followed on Ubuntu18.04

    [email protected]:~/Downloads/RedEyeRemover$ g++ -std=c++11 removeRedEyes.cpp `pkg-config –libs –cflags opencv` -o removeRedEyes
    /tmp/ccQgjaHc.o: In function `main’:
    removeRedEyes.cpp:(.text+0x2e6): undefined reference to `cv::imread(cv::String const&, int)’
    removeRedEyes.cpp:(.text+0x33d): undefined reference to `cv::CascadeClassifier::CascadeClassifier(cv::String const&)’
    removeRedEyes.cpp:(.text+0xb8e): undefined reference to `cv::imshow(cv::String const&, cv::_InputArray const&)’
    removeRedEyes.cpp:(.text+0xbf4): undefined reference to `cv::imshow(cv::String const&, cv::_InputArray const&)’
    /tmp/ccQgjaHc.o: In function `cv::String::String(char const*)’:
    removeRedEyes.cpp:(.text._ZN2cv6StringC2EPKc[_ZN2cv6StringC5EPKc]+0x54): undefined reference to `cv::String::allocate(unsigned long)’
    /tmp/ccQgjaHc.o: In function `cv::String::~String()’:
    removeRedEyes.cpp:(.text._ZN2cv6StringD2Ev[_ZN2cv6StringD5Ev]+0x14): undefined reference to `cv::String::deallocate()’
    /tmp/ccQgjaHc.o: In function `cv::String::operator=(cv::String const&)’:
    removeRedEyes.cpp:(.text._ZN2cv6StringaSERKS0_[_ZN2cv6StringaSERKS0_]+0x28): undefined reference to `cv::String::deallocate()’
    collect2: error: ld returned 1 exit status

    Reply

  68. I’m trying to install OpenCV 3.3.1 on Ubuntu 18.04 with Python version is 3.6.4 in Anacoda, following this blog “Install OpenCV3 on Ubuntu | Learn OpenCV”. However it does NOT working out for the compiling at step 5.3: make -j4 with the following errors. (nproc =4 in my computer)
    —
    collect2: error: ld returned 1 exit status
    modules/plot/CMakeFiles/example_plot_plot_demo.dir/build.make:100: recipe for target ‘bin/example_plot_plot_demo’ failed
    make[2]: *** [bin/example_plot_plot_demo] Error 1
    CMakeFiles/Makefile2:4766: recipe for target ‘modules/plot/CMakeFiles/example_plot_plot_demo.dir/all’ failed
    make[1]: *** [modules/plot/CMakeFiles/example_plot_plot_demo.dir/all] Error 2
    [ 44%] Linking CXX executable ../../bin/example_surface_matching_ppf_normal_computation
    [ 44%] Built target example_surface_matching_ppf_normal_computation
    Makefile:162: recipe for target ‘all’ failed
    make: *** [all] Error 2
    —
    Anyone can help me on this issue? thanks.

    Reply

  69. i built myself opencv-4.0 and I have already opencv-3.4.1 so in that case how to configure pkg-config, ideal case to have both pkg-config opencv341 and opencv40

    after install i followed
    make install
    sh -c ‘echo “/usr/local/lib” >> /etc/ld.so.conf’
    ldconfig

    and pkg-config seems not updated

    Reply

  70. Hello, Excellent script. The only issue is that I am not able to compile OpenCV with OpenGL support on ARM board (ODROID XU-4) for a possible conflict with different versions of openGL installed, for instance OpenGL-ES. Do you have any suggestions for solving this problem?

    Reply

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