OpenCV display image test OK

Now I have tried Section 1.2's using OpenCV with gcc and CMake and found everything OK, except that I blindly copied the program and cmake files without understanding what they are doing.


OpneCV Tutorial 1.2 Using OpenCV with gcc and CMake

...

Steps

Create a program using OpenCV

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

#include <cv.h>

#include <highgui.h>

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:

project( DisplayImage )

find_package( OpenCV REQUIRED )

add_executable( DisplayImage DisplayImage )

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.

.END

pi@raspberrypi ~/fongvision/DisplayImage $ ls

CMakeCache.txt  cmake_install.cmake  DisplayImage      Makefile
CMakeFiles      CMakeLists.txt       DisplayImage.cpp  TestImage.jpg


pi@raspberrypi ~/fongvision/DisplayImage $ cat DisplayImage.cpp

#include <cv.h>
#include <highgui.h>

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;

  }


pi@raspberrypi ~/fongvision/DisplayImage $ cat CMakeLists.txt

project( DisplayImage )
find_package( OpenCV REQUIRED )
add_executable( DisplayImage DisplayImage )

target_link_libraries( DisplayImage ${OpenCV_LIBS} )

.END