content: /**
   * @file Filter2D_demo.java
   * @brief Sample code that shows how to implement your own linear filters by using filter2D function
   */
  
  import org.opencv.core.*;
  import org.opencv.core.Point;
  import org.opencv.highgui.HighGui;
  import org.opencv.imgcodecs.Imgcodecs;
  import org.opencv.imgproc.Imgproc;
  
  class Filter2D_DemoRun {
  
      public void run(String[] args) {
          // Declare variables
          Mat src, dst = new Mat();
  
          Mat kernel = new Mat();
          Point anchor;
          double delta;
          int ddepth;
          int kernel_size;
          String window_name = "filter2D Demo";
  
          //! [load]
          String imageName = ((args.length > 0) ? args[0] : "../data/lena.jpg");
  
          // Load an image
          src = Imgcodecs.imread(imageName, Imgcodecs.IMREAD_COLOR);
  
          // Check if image is loaded fine
          if( src.empty() ) {
              System.out.println("Error opening image!");
              System.out.println("Program Arguments: [image_name -- default ../data/lena.jpg] \n");
              System.exit(-1);
          }
          //! [load]
  
          //! [init_arguments]
          // Initialize arguments for the filter
          anchor = new Point( -1, -1);
          delta = 0.0;
          ddepth = -1;
          //! [init_arguments]
  
          // Loop - Will filter the image with different kernel sizes each 0.5 seconds
          int ind = 0;
          while( true )
          {
              //! [update_kernel]
              // Update kernel size for a normalized box filter
              kernel_size = 3 + 2*( ind%5 );
              Mat ones = Mat.ones( kernel_size, kernel_size, CvType.CV_32F );
              Core.multiply(ones, new Scalar(1/(double)(kernel_size*kernel_size)), kernel);
              //! [update_kernel]
  
              //! [apply_filter]
              // Apply filter
              Imgproc.filter2D(src, dst, ddepth , kernel, anchor, delta, Core.BORDER_DEFAULT );
              //! [apply_filter]
              HighGui.imshow( window_name, dst );
  
              int c = HighGui.waitKey(500);
              // Press 'ESC' to exit the program
              if( c == 27 )
              { break; }
  
              ind++;
          }
  
          System.exit(0);
      }
  }
  
  public class Filter2D_Demo {
      public static void main(String[] args) {
          // Load the native library.
          System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
          new Filter2D_DemoRun().run(args);
      }
  }
  