Using OpenCV with gcc and CMake

Note

 

We assume that you have successfully installed OpenCV in your workstation.

• The easiest way of using OpenCV in your code is to use CMake. A few advantages (taken from the Wiki):
  1. No need to change anything when porting between Linux and Windows
  2. Can easily be combined with other tools by CMake( i.e. Qt, ITK and VTK )
• If you are not familiar with CMake, checkout the tutorial on its website.

Steps

Create a program using OpenCV

Let’s use a simple program such as DisplayImage.cpp shown below.

#include <stdio.h>#include <opencv2/opencv.hpp>using namespace cv;int main( int argc, char** argv ){  Mat image;  image = imread( argv[1], 1 );  if( argc != 2 || !image.data )    {      printf( "No image data \n" );      return -1;    }  namedWindow( "Display Image", CV_WINDOW_AUTOSIZE );  imshow( "Display Image", image );  waitKey(0);  return 0;}

Create a CMake file

Now you have to create your CMakeLists.txt file. It should look like this:

cmake_minimum_required(VERSION 2.8)project( DisplayImage )find_package( OpenCV REQUIRED )add_executable( DisplayImage DisplayImage.cpp )target_link_libraries( DisplayImage ${OpenCV_LIBS} )

Generate the executable

This part is easy, just proceed as with any other project using CMake:

cd <DisplayImage_directory>cmake .make

Result

By now you should have an executable (called DisplayImage in this case). You just have to run it giving an image location as an argument, i.e.:

./DisplayImage lena.jpg

You should get a nice window as the one shown below: