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;

}