da/dad/samples_2cpp_2snippets_2edge_8cpp-example.html

#include "opencv2/core/utility.hpp"

#include "opencv2/imgproc.hpp"

#include "opencv2/imgcodecs.hpp"

#include "opencv2/highgui.hpp"


#include <stdio.h>


using namespace cv;

using namespace std;


int edgeThresh = 1;

int edgeThreshScharr=1;


Mat image, gray, blurImage, edge1, edge2, cedge;


const char* window_name1 = "Edge map : Canny default (Sobel gradient)";

const char* window_name2 = "Edge map : Canny with custom gradient (Scharr)";


// define a trackbar callback

static void onTrackbar(int, void*)

{

    blur(gray, blurImage, Size(3,3));


 // Run the edge detector on grayscale

    Canny(blurImage, edge1, edgeThresh, edgeThresh*3, 3);

    cedge = Scalar::all(0);


    image.copyTo(cedge, edge1);

    imshow(window_name1, cedge);


 Mat dx,dy;

    Scharr(blurImage,dx,CV_16S,1,0);

    Scharr(blurImage,dy,CV_16S,0,1);

    Canny( dx,dy, edge2, edgeThreshScharr, edgeThreshScharr*3 );

    cedge = Scalar::all(0);

    image.copyTo(cedge, edge2);

    imshow(window_name2, cedge);

}


static void help(const char** argv)

{

    printf("\nThis sample demonstrates Canny edge detection\n"

 "Call:\n"

 "    %s [image_name -- Default is fruits.jpg]\n\n", argv[0]);

}


const char* keys =

{

 "{help h||}{@image |fruits.jpg|input image name}"

};


int main( int argc, const char** argv )

{

    help(argv);

 CommandLineParser parser(argc, argv, keys);

 string filename = parser.get<string>(0);


    image = imread(samples::findFile(filename), IMREAD_COLOR);

 if(image.empty())

    {

        printf("Cannot read image file: %s\n", filename.c_str());

        help(argv);

 return -1;

    }

    cedge.create(image.size(), image.type());

 cvtColor(image, gray, COLOR_BGR2GRAY);


 // Create a window

 namedWindow(window_name1, 1);

 namedWindow(window_name2, 1);


 // create a toolbar

 createTrackbar("Canny threshold default", window_name1, &edgeThresh, 100, onTrackbar);

 createTrackbar("Canny threshold Scharr", window_name2, &edgeThreshScharr, 400, onTrackbar);


 // Show the image

    onTrackbar(0, 0);


 // Wait for a key stroke; the same function arranges events processing

 waitKey(0);


 return 0;

}

cv::CommandLineParser
Designed for command line parsing.
Definition utility.hpp:915

cv::Mat
Comma-separated Matrix Initializer.
Definition mat.hpp:964

cv::Mat::copyTo
void copyTo(OutputArray m) const
Copies the matrix to another one.

cv::Mat::create
void create(int rows, int cols, int type)
Allocates new array data if needed.

cv::Size_
Template class for specifying the size of an image or rectangle.
Definition types.hpp:338

CV_16S
#define CV_16S
Definition interface.h:57

cv::waitKey
int waitKey(int delay=0)
Waits for a pressed key.

cv::namedWindow
void namedWindow(const String &winname, int flags=WINDOW_AUTOSIZE)
Creates a window.

cv::createTrackbar
int createTrackbar(const String &trackbarname, const String &winname, int *value, int count, TrackbarCallback onChange=0, void *userdata=0)
Creates a trackbar and attaches it to the specified window.

cv::imread
Mat imread(const String &filename, int flags=IMREAD_COLOR_BGR)
Loads an image from a file.

cv::cvtColor
void cvtColor(InputArray src, OutputArray dst, int code, int dstCn=0, AlgorithmHint hint=cv::ALGO_HINT_DEFAULT)
Converts an image from one color space to another.

highgui.hpp

main
int main(int argc, char *argv[])
Definition highgui_qt.cpp:3

imgcodecs.hpp

imgproc.hpp

cv
Definition core.hpp:107

std
STL namespace.

utility.hpp