opencv2使用形态学滤波对图像进行边缘及角点检測

#if !defined MORPHOF
#define MORPHOF

#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>

class MorphoFeatures {

private:

// threshold to produce binary image
int threshold;
// structuring elements used in corner detection
cv::Mat cross;
cv::Mat diamond;
cv::Mat square;
cv::Mat x;

void applyThreshold(cv::Mat& result) {

// Apply threshold on result
if (threshold>0)
cv::threshold(result, result, threshold, 255, cv::THRESH_BINARY_INV);
}

public:

MorphoFeatures() : threshold(-1), cross(5,5,CV_8U,cv::Scalar(0)),
diamond(5,5,CV_8U,cv::Scalar(1)),
square(5,5,CV_8U,cv::Scalar(1)),
x(5,5,CV_8U,cv::Scalar(0)){

// Creating the cross-shaped structuring element
for (int i=0; i<5; i++) {

cross.at<uchar>(2,i)= 1;
cross.at<uchar>(i,2)= 1;
}

// Creating the diamond-shaped structuring element
diamond.at<uchar>(0,0)= 0;
diamond.at<uchar>(0,1)= 0;
diamond.at<uchar>(1,0)= 0;
diamond.at<uchar>(4,4)= 0;
diamond.at<uchar>(3,4)= 0;
diamond.at<uchar>(4,3)= 0;
diamond.at<uchar>(4,0)= 0;
diamond.at<uchar>(4,1)= 0;
diamond.at<uchar>(3,0)= 0;
diamond.at<uchar>(0,4)= 0;
diamond.at<uchar>(0,3)= 0;
diamond.at<uchar>(1,4)= 0;

// Creating the x-shaped structuring element
for (int i=0; i<5; i++) {

x.at<uchar>(i,i)= 1;
x.at<uchar>(4-i,i)= 1;
}
}

void setThreshold(int t) {

threshold= t;
}

int getThreshold() const {

return threshold;
}

cv::Mat getEdges(const cv::Mat &image) {

// Get the gradient image
cv::Mat result;
cv::morphologyEx(image,result,cv::MORPH_GRADIENT,cv::Mat());

// Apply threshold to obtain a binary image
applyThreshold(result);

return result;
}

cv::Mat getCorners(const cv::Mat &image) {

cv::Mat result;

// Dilate with a cross
cv::dilate(image,result,cross);

// Erode with a diamond
cv::erode(result,result,diamond);

cv::Mat result2;
// Dilate with a X
cv::dilate(image,result2,x);

// Erode with a square
cv::erode(result2,result2,square);

// Corners are obtained by differencing
// the two closed images
cv::absdiff(result2,result,result);

// Apply threshold to obtain a binary image
applyThreshold(result);

return result;
}

void drawOnImage(const cv::Mat& binary, cv::Mat& image) {

cv::Mat_<uchar>::const_iterator it= binary.begin<uchar>();
cv::Mat_<uchar>::const_iterator itend= binary.end<uchar>();

// for each pixel
for (int i=0; it!= itend; ++it,++i) {
if (!*it)
cv::circle(image,cv::Point(i%image.step,i/image.step),5,cv::Scalar(255,0,0));
}
}
};

#endif

#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include "morphoFeatures.h"

int main()
{
// Read input image
cv::Mat image= cv::imread("d:/test/opencv/building.jpg",0);
if (!image.data)
return 0;

// Display the image
cv::namedWindow("Image");
cv::imshow("Image",image);

// Create the morphological features instance
MorphoFeatures morpho;
morpho.setThreshold(40);

// Get the edges
cv::Mat edges;
edges= morpho.getEdges(image);

// Display the edge image
cv::namedWindow("Edge Image");
cv::imshow("Edge Image",edges);

// Get the corners
morpho.setThreshold(-1);
cv::Mat corners;
corners= morpho.getCorners(image);
cv::morphologyEx(corners,corners,cv::MORPH_TOPHAT,cv::Mat());
cv::threshold(corners, corners, 40, 255, cv::THRESH_BINARY_INV);

// Display the corner image
cv::namedWindow("Corner Image");
cv::imshow("Corner Image",corners);

// Display the corner on the image
morpho.drawOnImage(corners,image);
cv::namedWindow("Corners on Image");
cv::imshow("Corners on Image",image);

cv::waitKey();

return 0;
}