opencv-图像抠图

首先将原图像灰度化，二值化，然后提取轮廓，进行排除、去噪处理之后用drawContours()函数把轮廓填充为白色。具体做法是：

Mat hole(res.size(), CV_8U, Scalar(0)); //新建一个黑色的遮罩图层

cv::drawContours(hole, contours1, -1, Scalar(255), CV_FILLED); //在遮罩图层上，将轮廓里面的空间用白色像素填充

之后将原图用copyTo()函数叠加到遮罩图层上，就大功告成了。

#include "opencv2/imgproc.hpp"#include "opencv2/highgui.hpp"#include <iostream>using namespace cv;using namespace std;void main() {Mat original = imread("D:\\res.png");namedWindow("My original");imshow("My original", original);Mat gray = original;cv::cvtColor(gray, gray, CV_RGB2GRAY);//灰度化int thresh_size = (100 / 4) * 2 + 1; //自适应二值化阈值adaptiveThreshold(gray, gray, 255, CV_ADAPTIVE_THRESH_GAUSSIAN_C, CV_THRESH_BINARY_INV, thresh_size, thresh_size / 3);morphologyEx(gray, gray, MORPH_OPEN, Mat());//形态学开运算去噪点vector<vector<Point> > contours;cv::findContours(gray, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_NONE); //找轮廓vector<vector<Point>> contours1;for (int i = 0; i < contours.size(); ++i){if (contours[i].size() > 200)//将比较小的轮廓剔除掉{contours1.push_back(contours[i]);}}/*可以加入以下功能*///vector<vector<Point>> contours2;//vector<Point> approx_poly;//存放顶点//for (int i = 0; i < contours1.size(); ++i)//{//double eps = contours1[i].size()*0.08;//精度//approxPolyDP(contours1[i], approx_poly, eps, true);//用另一条顶点较少的曲线来逼近一条曲线或者一个多边形//if ((approx_poly.size() != 4) || (!isContourConvex(approx_poly)))//提取只有4个顶点的轮廓和凸多边形//{//continue;//}//else {//contours2.push_back(contours1[i]);//}//}Mat hole(gray.size(), CV_8U, Scalar(0)); //遮罩图层cv::drawContours(hole, contours1, -1, Scalar(255), CV_FILLED); //在遮罩图层上，用白色像素填充轮廓namedWindow("My hole");imshow("My hole", hole);Mat crop(original.rows, original.cols, CV_8UC3);original.copyTo(crop, hole);//将原图像拷贝进遮罩图层namedWindow("My warpPerspective");imshow("My warpPerspective", crop);waitKey(0);}