腐蚀和膨胀属于形态学操作。
腐蚀和膨胀
腐蚀是指：将卷积核B滑过图像A，找出卷积核区域内最小像素值作为锚点像素值。这一操作可以扩大低像素值区域。
膨胀是指：将卷积核B滑过图像A，找出卷积核区域内最大像素值作为锚点像素值。这一操作可以缩小低像素值区域。
通过前面的卷积可以看出，膨胀相当于“最大值”滤波器，腐蚀相当于”最小值“滤波器。滤波器的形状我们可以自己定义。
其他形态学操作
开运算
先对图像腐蚀，再膨胀
[ exttt{dst} = mathrm{open} ( exttt{src} , exttt{element} )= mathrm{dilate} ( mathrm{erode} ( exttt{src} , exttt{element} ))
]
闭运算
先膨胀再腐蚀
[ exttt{dst} = mathrm{close} ( exttt{src} , exttt{element} )= mathrm{erode} ( mathrm{dilate} ( exttt{src} , exttt{element} ))
]
形态梯度
膨胀图和腐蚀图之差
[ exttt{dst} = mathrm{morph\_grad} ( exttt{src} , exttt{element} )= mathrm{dilate} ( exttt{src} , exttt{element} )- mathrm{erode} ( exttt{src} , exttt{element} )
]
顶冒
原图和开运算图之差
[ exttt{dst} = mathrm{tophat} ( exttt{src} , exttt{element} )= exttt{src} - mathrm{open} ( exttt{src} , exttt{element} )
]
黑冒
闭运算结果和原图之差
[ exttt{dst} = mathrm{blackhat} ( exttt{src} , exttt{element} )= mathrm{close} ( exttt{src} , exttt{element} )- exttt{src}
]
实验代码
常用函数
Mat getStructuringElement(int shape, Size ksize, Point anchor=Point(-1,-1))
获取卷积核，卷积核中，对应形状位置的元素都为1.
shape:
MORPH_RECT:矩形
MORPH_ELLIPSE:椭圆
MORPH_CROSS:十字形
ksize:
核大小
void morphologyEx(InputArray src, OutputArray dst, int op, InputArray kernel, Point anchor=Point(-1,-1), int iterations=1, int borderType=BORDER_CONSTANT, const Scalar& borderValue=morphologyDefaultBorderValue() )
src:输入图像
dst:结果图像
op:操作MORPH_OPEN开运算，MORPH_CLOSE闭运算、MORPH_GRADIENT形态梯度、MORPH_TOPHAT钉帽、MORPH_BLACKHAT黑冒
代码
#include <iostream>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
using namespace std;
int main(int argc, char* argv[]){
const char* path = "";
Mat img = imread(path);
if (!img.data){
cout << "Wrong Image" << endl;
return -1;
}
Mat kern = getStructuringElement(MORPH_RECT, Size(5, 5));
Mat erosion_img, dilate_img;
//腐蚀
erode(img, erosion_img, kern);
//膨胀
dilate(img, dilate_img, kern);
imshow("original image", img);
imshow("erosion image", erosion_img);
imshow("dilate image", dilate_img);
Mat open_mat, close_mat, gradient_mat, tophat_mat, blackhat_mat;
morphologyEx(img, open_mat, MORPH_OPEN, kern);
morphologyEx(img, close_mat, MORPH_CLOSE, kern);
morphologyEx(img, gradient_mat, MORPH_GRADIENT, kern);
morphologyEx(img, tophat_mat, MORPH_TOPHAT, kern);
morphologyEx(img, blackhat_mat, MORPH_BLACKHAT, kern);
imshow("Opening", open_mat);
imshow("Closing", close_mat);
imshow("Grandient", gradient_mat);
imshow("Tohat", tophat_mat);
imshow("Black", blackhat_mat);
cvWaitKey(0);
return 0;
}