OpenCV - Calculating edge strength of image

Question

I am new to image processing and I need to calculate the strength of edges present in an image. Assume a situation where you have an image and you add blur effect to that image. The strength of the edges of these two images are different. I need to calculate that edge strength for both images separately.

So far I have got the canny edge detection of the image using the code below.

  Mat src1;
  src1 = imread("D.PNG", CV_LOAD_IMAGE_COLOR);
  namedWindow("Original image", CV_WINDOW_AUTOSIZE);
  imshow("Original image", src1);
  Mat gray, edge, draw;
  cvtColor(src1, gray, CV_BGR2GRAY);
  Canny(gray, edge, 50, 150, 3);
  edge.convertTo(draw, CV_8U);
  namedWindow("image", CV_WINDOW_AUTOSIZE);
  imshow("image", draw);
  waitKey(0);
  return 0;

Is there any method to calculate of the strength of this edge image..?

Answer 1

mean will give you the mean value of your image. If you're using Canny as above you can do:

Scalar pixelMean = mean(draw);

To get the mean of only the edge pixels, you would use the image as the mask as well:

Scalar edgeMean = mean(draw, draw);

Unfortunately, since Canny sets all edge pixels to 255 , your mean will always be 255 . If this is the measure you're looking for, you'll probably want to use Sobel (after Gaussian Blur) and calculate the gradients to get the relative edge strengths.