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OpenCV how to use Sobel, Laplacian, Canny for edge detection, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can get something.

Brief introduction

The general steps of OpenCV edge detection are:

Filter

Enhancement

Detection

The commonly used edge detection operators and filters are:

Sobel operator

Laplacian operator

Canny operator

Scharr filter

The following uses Sobel, Laplacian and Canny operators for edge detection. The picture is a random download from the Internet.

Code import cv2#*Sobel Edge Detection * * def edge_sobel (src): kernelSize = (3,3) gausBlurImg = cv2.GaussianBlur (src, kernelSize, 0) # convert to grayscale image channels = src.shape [2] if channels > 1: src_gray = cv2.cvtColor (gausBlurImg Cv2.COLOR_RGB2GRAY) else: src_gray = src.clone () scale = 1 delta = 0 depth = cv2.CV_16S # find X direction gradient (create grad_x, grad_y matrix) grad_x = cv2.Sobel (src_gray, depth, 1,0) abs_grad_x = cv2.convertScaleAbs (grad_x) # find Y direction gradient grad_y = cv2.Sobel (src_gray, depth, 0 1) abs_grad_y = cv2.convertScaleAbs (grad_y) # merge gradient (approximate) edgeImg = cv2.addWeighted (abs_grad_x, 0.5, abs_grad_y, 0.5 0) return edgeImg#*Laplacian edge detection * * def edge_laplacian (src): scale = 1 delta = 0 depth = cv2.CV_16S if src.shape [2] > 1: src_gray = cv2.cvtColor (src Cv2.COLOR_RGB2GRAY) else: src_gray = src.clone () kernelSize = (3,3) gausBlurImg = cv2.GaussianBlur (src_gray, kernelSize, 0) laplacianImg = cv2.Laplacian (gausBlurImg, depth) KernelSize) edgeImg = cv2.convertScaleAbs (laplacianImg) return edgeImg#*Canny Edge Detection * * def edge_canny (src, threshold1, threshold2): kernelSize = (3,3) gausBlurImg = cv2.GaussianBlur (src, kernelSize, 0) edgeImg = cv2.Canny (gausBlurImg, threshold1) Threshold2) return edgeImg#* main function * * imgSrc = cv2.imread ("1.jpg") sobelImg = edge_sobel (imgSrc) laplacianImg = edge_laplacian (imgSrc) cannyImg = edge_canny (imgSrc, 20,60) cv2.imshow ("Origin", imgSrc) cv2.imshow ("Sobel", sobelImg) cv2.imshow ("Laplacian" LaplacianImg) cv2.imshow ("Canny", cannyImg) cv2.waitKey (0) cv2.destroyAllWindows () effect

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