samples/cpp/tutorial_code/ImgProc/Pyramids/Pyramids.cpp

An example using pyrDown and pyrUp functions

 
#include "iostream"
#include "opencv2/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
 
using namespace std;
using namespace cv;
 
const char* window_name = "Pyramids Demo";
 
int main( int argc, char** argv )
{
 cout << "\n Zoom In-Out demo \n "
 "------------------ \n"
 " * [i] -> Zoom in \n"
 " * [o] -> Zoom out \n"
 " * [ESC] -> Close program \n" << endl;
 
 const char* filename = argc >=2 ? argv[1] : "chicky_512.png";
 
 // Loads an image
 Mat src = imread( samples::findFile( filename ) );
 
 // Check if image is loaded fine
 if(src.empty()){
 printf(" Error opening image\n");
 printf(" Program Arguments: [image_name -- default chicky_512.png] \n");
 return EXIT_FAILURE;
 }
 
 for(;;)
 {
 imshow( window_name, src );
 char c = (char)waitKey(0);
 
 if( c == 27 )
 { break; }
 else if( c == 'i' )
 { pyrUp( src, src, Size( src.cols*2, src.rows*2 ) );
 printf( "** Zoom In: Image x 2 \n" );
 }
 else if( c == 'o' )
 { pyrDown( src, src, Size( src.cols/2, src.rows/2 ) );
 printf( "** Zoom Out: Image / 2 \n" );
 }
 }
 
 return EXIT_SUCCESS;
}