from https://www.vultr.com/docs/how-to-install-opencv-on-centos-7

How to Install OpenCV on CentOS 7

Published on: Mon, Oct 23, 2017 at 2:41 pm EST

CentOS System Admin



OpenCV, also known as Open Source Computer Vision Library, is an open source cross-platform computer vision algorithm library. Nowadays, OpenCV is being widely used in all kind of visual processing areas, such as facial recognition, gesture recognition, human-computer interaction, Object identification, motion tracking, etc.

OpenCV can be deployed on various platforms, including Windows, Linux, Android, iOS, etc. In this article, I will show you how to compile and install OpenCV 3.3.0, the latest stable release of OpenCV at the time I wrote this article, on the CentOS 7 x64 operating system.

Prerequisites

A Vultr CentOS 7 x64 server instance.
Logging in as root.
The server instance has been updated to the latest stable status.


Step 1: Install dependencies for OpenCV

Use the following commands to install all required dependencies for compiling OpenCV:
yum groupinstall "Development Tools" -y
yum install cmake gcc gtk2-devel numpy pkconfig -y


Step 2: Download the OpenCV 3.3.0 archive

Download and uncompress OpenCV 3.3.0 archive as below:
cd
wget https://github.com/opencv/opencv/archive/3.3.0.zip
unzip 3.3.0.zip


Step 3: Compile and install OpenCV 3.3.0

Use the following commands to compile and install OpenCV, and compiled OpenCV files will be saved in the /usr/local directory.
cd opencv-3.3.0
mkdir build
cd build
cmake -D CMAKE_BUILD_TYPE=DEBUG -D CMAKE_INSTALL_PREFIX=/usr/local ..
make
make install


Step 4: Configure required variables

In addtion to compiling and installing files, you need to specify path info for pkgconfig and OpenCV:
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig/
echo '/usr/local/lib/' >> /etc/ld.so.conf.d/opencv.conf
ldconfig


Step 5 (optional): Run tests

To test your OpenCV installation, you can download extra test data from OpenCV extra repository:
cd
git clone https://github.com/opencv/opencv_extra.git
export OPENCV_TEST_DATA_PATH=/root/opencv_extra/testdata


In the cmake build directory, you will find several test executables named in the same kind of format opencv_test_*. Run any one you are interested in to perform a test. For example:
cd /root/opencv-3.3.0/build/bin
ls
./opencv_test_photo


This concludes the tutorial. Thanks for reading.


サンプルプログラムのコンパイル


g++ test.cpp -I/usr/local/include/opencv2 -I/usr/local/include/opencv -L/usr/local/lib -lopencv_core -lopencv_imgcodecs -lopencv_highgui