opencv/samples/cpp/tutorial_code/ImgTrans/Laplace_Demo.cpp

/**
 * @file Laplace_Demo.cpp
 * @brief Sample code showing how to detect edges using the Laplace operator
 * @author OpenCV team
 */

#include "opencv2/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"

using namespace cv;

/**
 * @function main
 */
int main( int, char** argv )
{

  Mat src, src_gray, dst;
  int kernel_size = 3;
  int scale = 1;
  int delta = 0;
  int ddepth = CV_16S;
  const char* window_name = "Laplace Demo";

  /// Load an image
  src = imread( argv[1], IMREAD_COLOR );

  if( src.empty() )
    { return -1; }

  /// Remove noise by blurring with a Gaussian filter
  GaussianBlur( src, src, Size(3,3), 0, 0, BORDER_DEFAULT );

  /// Convert the image to grayscale
  cvtColor( src, src_gray, COLOR_RGB2GRAY );

  /// Create window
  namedWindow( window_name, WINDOW_AUTOSIZE );

  /// Apply Laplace function
  Mat abs_dst;

  Laplacian( src_gray, dst, ddepth, kernel_size, scale, delta, BORDER_DEFAULT );
  convertScaleAbs( dst, abs_dst );

  /// Show what you got
  imshow( window_name, abs_dst );

  waitKey(0);

  return 0;
}