Mounted on Ubuntu 18.04 OpenCV 4 (C ++ and Python)

 

OpenCV on November 20 announced the OpenCV-3.4.4 and OpenCV-4.0.0. These versions have a lot of bug fixes and other changes. Release Highlights are as follows:

• OpenCV is now C ++ 11 libraries need to meet the C ++ 11 standard compilers. The minimum required CMake version has been upgraded to 3.5.1.
• Many C API from OpenCV 1.x has been removed.
• Persistent (storage and loading structured data in XML, YAML or JSON) is the core module has been completely re-implemented in C ++, and also lost C API.
• Adding a new module G-API, it can be very effective as based on the image processing pipeline of the graphics engine.
• dnn module now includes experimental Vulkan backend and support network ONNX format.
• Kinect Fusion popular algorithms have been implemented and optimized (the OpenCL) for the CPU and the GPU
  the QR code detector and decoder module has been added to objdetect.
• DIS highly efficient and high quality dense optical flow algorithm proceeds to opencv_contrib from the video module.

In this article, we will provide a bash script, used on Ubuntu 18.04 installed OpenCV-4.0 (C ++ and Python 3.6). We will also briefly studied to understand the contents of the script. Note that this script will install OpenCV in the local directory, rather than the entire system.

Seeking Ubuntu 16.04 the installation script ? Take a look at this blog .

1. Installation OpenCV 4.0

Step 0: Choose the version you want to install OpenCV

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echo "OpenCV installation by learnOpenCV.com" # Define OpenCV Version to install cvVersion= "master"

We will also clean up the builddirectory and create installationa directory.

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# Clean build directories rm -rf opencv /build rm -rf opencv_contrib /build

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# Create directory for installation mkdir installation mkdir installation /OpenCV- "$cvVersion"

Finally, we will be the current working directory is stored in the cwdvariable. We will in this blog, this directory is referred OpenCV_Home_Dir .

1 2	# Save current working directory cwd=$( pwd )

Step 1: Update package

1 2	sudo apt -y update sudo apt -y upgrade

If you still can not install OpenCV on your system, but want to start using it, we recommend using our pre-installed mirror docker OpenCV, Dlib, miniconda and jupyter notebook and this blog other dependencies described .

Step 2: Install the OS library

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sudo apt -y remove x264 libx264-dev   ## Install dependencies sudo apt -y install build-essential checkinstall cmake pkg-config yasm sudo apt -y install git gfortran sudo apt -y install libjpeg8-dev libpng-dev   sudo apt -y install software-properties-common sudo add-apt-repository "deb http://security.ubuntu.com/ubuntu xenial-security main" sudo apt -y update   sudo apt -y install libjasper1 sudo apt -y install libtiff-dev   sudo apt -y install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev sudo apt -y install libxine2-dev libv4l-dev cd /usr/include/linux sudo ln -s -f .. /libv4l1-videodev .h videodev.h cd "$cwd"   sudo apt -y install libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev sudo apt -y install libgtk2.0-dev libtbb-dev qt5-default sudo apt -y install libatlas-base-dev sudo apt -y install libfaac-dev libmp3lame-dev libtheora-dev sudo apt -y install libvorbis-dev libxvidcore-dev sudo apt -y install libopencore-amrnb-dev libopencore-amrwb-dev sudo apt -y install libavresample-dev sudo apt -y install x264 v4l-utils   # Optional dependencies sudo apt -y install libprotobuf-dev protobuf-compiler sudo apt -y install libgoogle-glog-dev libgflags-dev sudo apt -y install libgphoto2-dev libeigen3-dev libhdf5-dev doxygen

On Ubuntu 18.04 looking for OpenCV 3.4.4 of the installation script ? Take a look at this blog .

Step 3: Install Python library

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sudo apt -y install python3-dev python3-pip sudo -H pip3 install -U pip numpy sudo apt -y install python3-testresources

We will also install virtualenvand virtualenvwrappermodules to create a virtual Python environment.

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cd $cwd ############ For Python 3 ############ # create virtual environment python3 -m venv OpenCV- "$cvVersion" -py3 echo "# Virtual Environment Wrapper" >> ~/.bashrc echo "alias workoncv-$cvVersion=\"source $cwd/OpenCV-$cvVersion-py3/bin/activate\"" >> ~/.bashrc source "$cwd" /OpenCV- "$cvVersion" -py3 /bin/activate   # now install python libraries within this virtual environment pip install wheel numpy scipy matplotlib scikit-image scikit-learn ipython dlib    # quit virtual environment deactivate

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Download the installation script

Step 4: Download and opencv_contrib opencv

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

Step 5: Using the Compiler contrib module and install OpenCV

First, we navigate to the build directory.

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cd opencv mkdir build cd build

Next, we began to compile and install process.

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cmake -D CMAKE_BUILD_TYPE=RELEASE \              -D CMAKE_INSTALL_PREFIX=$cwd /installation/OpenCV- "$cvVersion" \              -D INSTALL_C_EXAMPLES=ON \              -D INSTALL_PYTHON_EXAMPLES=ON \              -D WITH_TBB=ON \              -D WITH_V4L=ON \              -D OPENCV_PYTHON3_INSTALL_PATH=$cwd /OpenCV- $cvVersion-py3 /lib/python3 .5 /site-packages \          -D WITH_QT=ON \          -D WITH_OPENGL=ON \          -D OPENCV_EXTRA_MODULES_PATH=../.. /opencv_contrib/modules \          -D BUILD_EXAMPLES=ON ..

对于OpenCV的系统范围安装， 请将 CMAKE_INSTALL_PREFIX 更改为CMAKE_INSTALL_PREFIX = / usr / local \。

1 2	make -j4 make install

2.如何在C ++中使用OpenCV

使用CMakeLists.txt

CMakeLists.txt的基本结构如下：

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cmake_minimum_required(VERSION 3.1) # Enable C++11 set (CMAKE_CXX_STANDARD 11) set (CMAKE_CXX_STANDARD_REQUIRED TRUE)

您必须设置OpenCV_DIR，如下所示。

1	SET(OpenCV_DIR <OpenCV_Home_Dir> /installation/OpenCV-master/lib/cmake/opencv4 )

确保使用正确的路径替换OpenCV_Home_Dir。例如，在我的情况下：

1	SET(OpenCV_DIR /home/hp/OpenCV_installation/installation/OpenCV-master/lib/cmake/opencv4 )

完成CMakeLists.txt后，请按照以下步骤操作。

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mkdir build && cd build cmake .. cmake --build . --config Release

这将在构建目录中生成可执行文件。

3.如何在Python中使用OpenCV

要使用使用Python脚本安装的OpenCV版本，首先要激活正确的Python虚拟环境。

对于OpenCV-4：Python 3

1	workon OpenCV-master-py3

激活虚拟环境后，即可进入Python shell并测试OpenCV版本。

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ipython import cv2 print(cv2.__version__)

希望这个脚本证明对你有用:)。请继续关注更多有趣的内容。如有任何疑问，请随时在下方发表评论，我们会尽快回复您。

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