效果图:

代码:
#include <opencv2/opencv.hpp>
#include <iostream>
#include <math.h>
using namespace cv;
using namespace std;
Mat src, dst,dst2;
//膨胀腐蚀的应用:消除噪声
int main()
{
//原图
src = imread(".//pic//ABC.png", IMREAD_UNCHANGED);
namedWindow("input image", CV_WINDOW_AUTOSIZE);
imshow("input image", src);
//转成灰度图
Mat gray_src;
cvtColor(src, gray_src, CV_BGR2GRAY);
imshow("gray image", gray_src);
//转成二值图
Mat binImg;
//255:二值图像的最大值
//ADAPTIVE_THRESH_MEAN_C:自适应方法
//THRESH_BINARY:阈值类型
//15:块大小
//取反可以把目标变白,灰度值大
adaptiveThreshold(~gray_src, binImg, 255, ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 15, 0);
imshow("bin image", binImg);
Mat tmp;
int s = 3;
Mat structureElement = getStructuringElement(MORPH_RECT, Size(s, s), Point(-1, -1));
erode(binImg, tmp, structureElement, Point(-1, -1));
imshow("腐蚀后的图", tmp);
dilate(tmp, dst, structureElement, Point(-1, -1));
dst = ~dst;
imshow("膨胀后的图", dst);
waitKey(0);
return 0;
}