## 1. Download

Download the two zip packages and unzip them.

## 2. Cmake

 1 2  cd opencv-4.2.0 mkdir build && cd build 

If you are simply using the C++ version of opencv for cpu, you can use the following cmake command

  1 2 3 4 5 6 7 8 9 10 11 12 13  cmake -D CMAKE_BUILD_TYPE=RELEASE \ -D CMAKE_INSTALL_PREFIX=/home/test/opt/opencv \ -D WITH_CUDA=OFF \ -D WITH_IPP=OFF \ -D OPENCV_EXTRA_MODULES_PATH=/home/test/opencv/opencv_contrib-4.2.0/modules \ -D OPENCV_GENERATE_PKGCONFIG=ON \ -D BUILD_opencv_python3=OFF \ -D BUILD_opencv_python2=OFF \ -D BUILD_opencv_hdf=OFF \ -D BUILD_EXAMPLES=ON .. make -j48 make install 

After installation, there will be an OpenCVConfig.cmake file in /home/test/opt/opencv/lib64/cmake/opencv4/ which tells cmake where to find the opencv libraries we compiled ourselves.

## 2.1 Adding to the system environment

Add the following variables to ~/.bashrc.

 1 2  export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/home/findhao/opt/opencv4.5.0/lib64/pkgconfig export LD_LIBRARY_PATH=/home/findhao/opt/opencv4.5.0/lib64/:$LD_LIBRARY_PATH 

## 3. Compile the program using opencv

smooth.cpp

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27  #include #include "opencv2/imgproc.hpp" #include "opencv2/imgcodecs.hpp" #include "opencv2/highgui.hpp" using namespace std; using namespace cv; /// Global Variables int DELAY_CAPTION = 1500; int DELAY_BLUR = 100; int MAX_KERNEL_LENGTH = 31; Mat src; Mat dst; char window_name[] = "Smoothing Demo"; int main( int argc, char ** argv ) { /// Load the source image const char* filename = argc >=2 ? argv[1] : "lena.jpg"; src = imread( "/home/test/tmp/test/lena.jpg", IMREAD_COLOR ); if (src.empty()) { printf(" Error opening image\n"); printf(" Usage:\n %s [image_name-- default lena.jpg] \n", argv[0]); return EXIT_FAILURE; } GaussianBlur( src, dst, Size( 13, 13 ), 0, 0 ); imwrite("out.jpg", dst); return 0; } 

CMakeList.txt

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32  # cmake needs this line cmake_minimum_required(VERSION 3.1) # Enable C++11 set(CMAKE_CXX_STANDARD 11) set(CMAKE_CXX_STANDARD_REQUIRED TRUE) # Define project name project(smooth) # Find OpenCV, you may need to set OpenCV_DIR variable # to the absolute path to the directory containing OpenCVConfig.cmake file # via the command line or GUI set(OpenCV_DIR /home/test/opt/opencv/lib/cmake/opencv4/) find_package(OpenCV REQUIRED) # If the package has been found, several variables will # be set, you can find the full list with descriptions # in the OpenCVConfig.cmake file. # Print some message showing some of them message(STATUS "OpenCV library status:") message(STATUS " config: ${OpenCV_DIR}") message(STATUS " version:${OpenCV_VERSION}") message(STATUS " libraries: ${OpenCV_LIBS}") message(STATUS " include path:${OpenCV_INCLUDE_DIRS}") add_definitions("-Wall -g") # Declare the executable target built from your sources add_executable(smooth smooth.cpp) # Link your application with OpenCV libraries target_link_libraries(smooth PRIVATE \${OpenCV_LIBS}) 

Just compile the smooth program with cmake and run it.

Referenece ttps://www.findhao.net/academic/2570.html