El Bruno

Hi !

The Canny edge detection is one the most popular algorithms, and it’s also +30 years old.

The Canny edge detector is an edge detection operator that uses a multi-stage algorithm to detect a wide range of edges in images. It was developed by John F. Canny in 1986.

OpenCV includes the Canny algorithm as part of the base set of operations to perform on an image. You only need 2 lines of code to get this output.

The OpenCV canny tutorial (see references) explain the different steps to detect edges:

• Noise Reduction
• Finding Intensity Gradient of the Image
• Non-maximum Suppression
• Hysteresis Thresholding

I’ll keep this simple, just sharing the code !

	using OpenCvSharp;
	var capture = new VideoCapture(0);
	var window = new Window("El Bruno – OpenCVSharp Effects demo");
	var image = new Mat();
	var imageNew = new Mat();
	bool applyCanny = false;
	bool run = true;
	while (run)
	{
	capture.Read(image);
	if (image.Empty()) break;
	if (applyCanny)
	imageNew = applyCannyEffect(image);
	else
	imageNew = image.Clone();
	window.ShowImage(imageNew);
	switch ((char)Cv2.WaitKey(100))
	{
	case (char)27: // Esc – Exit
	run = false;
	break;
	case 'c':
	applyCanny = !applyCanny;
	break;
	}
	}
	Mat applyCannyEffect(Mat image)
	{
	var newImage = new Mat();
	Cv2.Canny(image, newImage, 50, 200);
	return newImage;
	}

view raw opencvsharpnet5cannyeffect.cs hosted with ❤ by GitHub

That’s all for today!

References

• OpenCVSharp, https://github.com/shimat/opencvsharp
• Wikipedia, Canny Edge Detector
• OpenCV, Canny tutorial