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;
}