Opencv-Edge Detection

// ConsoleApplication3_6_23.cpp : Defines the entry point for the console application.//#include "stdafx.h"#include<opencv2/opencv.hpp>#include<iostream>using namespace std;using namespace cv;Mat src,dst,gray;int pro_type = 0;char* windowName = "demo";char* windowName1 = "demo_pro";void Image_pro(int,void*);int _tmain(int argc, _TCHAR* argv[]){src = imread("test.png");if(!src.data)return -1;namedWindow(windowName,CV_WINDOW_AUTOSIZE);imshow(windowName,src);GaussianBlur(src,src,Size(3,3),0,0,BORDER_DEFAULT);cvtColor(src,gray,CV_RGB2GRAY);namedWindow(windowName1,CV_WINDOW_AUTOSIZE);createTrackbar("Type : 0-sobel 1-laplace 2-canny /n",windowName1,&pro_type,2,Image_pro);Image_pro(0,0);waitKey(0);return 0;}void Image_pro(int,void*){Mat grd_x,grd_y;Mat abs_grd_x,abs_grd_y;Mat la_dst;switch (pro_type){case 0 :Sobel(gray,grd_x,CV_16S,1,0,3,1,0,BORDER_DEFAULT);convertScaleAbs(grd_x,abs_grd_x);Sobel(gray,grd_y,CV_16S,0,1,3,1,0,BORDER_DEFAULT);convertScaleAbs(grd_y,abs_grd_y);addWeighted(abs_grd_x,0.5,abs_grd_y,0.5,0,dst);break;case 1:Laplacian(gray,la_dst,CV_16S,3,1,0,BORDER_DEFAULT);convertScaleAbs(la_dst,dst);break;case 2:Canny(gray,dst,20,50 * 3,3);break;default:break;}imshow(windowName1,dst);}

Effect:

1,

Sobel( src_gray, grad_y, ddepth, 0, 1, 3, scale, delta, BORDER_DEFAULT );

This function accepts the following parameters:

• Src_gray: Input image in this example, element typeCv_8u
• Grad_x/Grad_y: Output image.
• Ddepth: Depth of the output image, setCv_16sAvoid overflow.
• X_order:XThe order of the direction.
• Y_order:YThe order of the direction.
• Scale,DeltaAndBorder_default: Use the default value
• 
  

2,

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

The function accepts the following parameters:

• Src_gray: Input image.
• DST: Output image
• Ddepth: Depth of the output image. Because the input image depth isCv_8u, Which must be defined hereDdepth=Cv_16sTo avoid overflow.
• Kernel_size: The kernel size of the Internally called Sobel operator, which is set to 3 in this example.
• Scale,DeltaAndBorder_default: Use the default value.
• 
  

Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );

Input parameters:

• Detected_edges: Original grayscale image
• Detected_edges: Output image (supports in-situ computation and can be input images)
• Lowthreshold: The value set by the user through trackbar.
• Highthreshold: Set to 3 times the low threshold value (recommended based on the Canny algorithm)
• Kernel_size: Set to 3 (Sobel kernel size, used internally)