5.4用形态学滤波器检测边缘和角点

主要参考：http://blog.csdn.net/thefutureisour/article/details/7574819

对于检测边缘，用morphologyEx函数就可以了，（cvMorphologyEx中形态操作的类型: CV_MOP_OPEN - 开运算 CV_MOP_CLOSE - 闭运算 CV_MOP_GRADIENT - 形态梯度 CV_MOP_TOPHAT - "顶帽" CV_MOP_BLACKHAT - "黑帽" ） 参数CV_MOP_GRADIENT - 形态梯度 大致就是检测到图像的变化的直线。  检测角点没有特定函数，就是对图像应用不同的结构元素膨胀腐蚀，然后做差分

//morphoFeatures.h

#if ! defined MORPHOF
#define MORPHOF

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

using namespace cv;

class MorphoFeatures
{
private:
	//产生二值图像的门限
	int threshold;
	//结构元
	Mat cross;
	Mat diamond;
	Mat square;
	Mat x;
	//对图像二值化
	void applyThreshold(Mat &result)
	{
		if(threshold>0)
			cv::threshold(result,result,threshold,255,THRESH_BINARY_INV);//,THRESH_BINARY_INV);
	}


public:
	//构造函数
	MorphoFeatures():threshold(-1),
		cross(5,5,CV_8U,Scalar(0)),
		diamond(5,5,CV_8U,Scalar(255)),
		square(5,5,CV_8U,Scalar(255)),
		x(5,5,CV_8U,Scalar(0))
	{
		//创建十字型结构元
		for(int i = 0; i < 5; i++)
		{
			cross.at<uchar>(2,i) = 255;
			cross.at<uchar>(i,2) = 255;
		}

		//创建菱形结构元：手动画，只需要把不是菱形的部分变白即可
		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;

		//创建X形
		for(int i = 0; i < 5; i++)
		{
			//主对角线
			x.at<uchar>(i,i) = 255;
			//副对角线
			x.at<uchar>(4-i,i) = 255;
		}

	}

	//设置门限函数
	void setThreshold(int t)
	{
		threshold = t;
	}

	//获取当前门限
	int getThreshold() const
	{
		return threshold;
	}

	//检测直线函数
	Mat getEdges(const Mat &image)
	{
		Mat result;
		//获取图像的梯度
		morphologyEx(image,result,cv::MORPH_GRADIENT,Mat());
		//imshow("检测直线",result);
		//结果二值化
		applyThreshold(result);
		return result;
	}

	//检测角点函数
	Mat getCorners(const Mat &image)
	{
		Mat result;
		dilate(image,result,cross);
		erode(result,result,diamond);
		Mat result2;
		dilate(image,result2,x);
		erode(result2,result2,square);
		absdiff(result2,result,result);
		applyThreshold(result);
		return result;
	}

	//在角点处画圆  morpho.drawOnImage(corners,image);
	void drawOnImage(const Mat &binary,Mat &image)
	{
		Mat_<uchar>::const_iterator it = binary.begin<uchar>();
		Mat_<uchar>::const_iterator itend = binary.end<uchar>();
		for(int i = 0;it != itend;++it,++i)
		{
			if(!*it)  //是黑点就执行
				circle(image,Point(i%image.step,i/image.step),5,Scalar(255,0,0));  //牛逼的坐标表达形式
		}
	}

};



#endif

以下是主函数：

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

int main()
{

	Mat image = imread("C:\\Users\\Administrator\\Desktop\\工作\\testp\\building.jpg",0);
	if(!image.data)
		return -1;
	imshow("源图像",image);

	MorphoFeatures morpho;
	morpho.setThreshold(40);

	//获取边沿
	Mat edges;
	edges = morpho.getEdges(image);
	imshow("边沿",edges);

	//获取角点
	morpho.setThreshold(-1);
	Mat corners;
	corners = morpho.getCorners(image);
//	imshow("corners",corners);
	morphologyEx(corners,corners,MORPH_TOPHAT,Mat()); //;顶帽
	//imshow("corners",corners);
	threshold(corners,corners,40,255,THRESH_BINARY_INV);
	//imshow("角点",corners);
	//imshow("corners",corners);
	//展示图片上的角点
	morpho.drawOnImage(corners,image);
	imshow("图片上的角点",image);


	waitKey(0);
	return 0;
}