C++ 来自 Mat 图像的 OpenCV 子图像
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OpenCV sub-image from a Mat image
提问by Og Namdik
Possible Duplicate:
Understanding region of interest in openCV 2.4
可能的重复：
了解 openCV 2.4 中的兴趣区域
i want to get a sub-image (the one bounded by the red box below) from an image (Mat format). how do i do this?
我想从图像（Mat 格式）中获取子图像（由下面的红色框包围的图像）。我该怎么做呢？
here's my progress so far:
这是我到目前为止的进展：
include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
using namespace std;
using namespace cv;
int main()
{
Mat imgray, thresh;
vector<vector<Point> >contours;
vector<Point> cnt;
vector<Vec4i> hierarchy;
Point leftmost;
Mat im = imread("igoy1.jpg");
cvtColor(im, imgray, COLOR_BGR2GRAY);
threshold(imgray, thresh, 127, 255, 0);
findContours(thresh, contours, hierarchy, RETR_TREE,CHAIN_APPROX_SIMPLE);
}
回答by Quentin Geissmann
You can start picking a contour (in your case, the contour corresponding to the hand). Then, you calculate the bounding rectangle for this contour. Finally you make a new matrix header from it.
您可以开始选择轮廓（在您的情况下，是与手相对应的轮廓）。然后，您计算此轮廓的边界矩形。最后，您可以从中创建一个新的矩阵标题。
int n=0;// Here you will need to define n differently (for instance pick the largest contour instead of the first one)
cv::Rect rect(contours[n]);
cv::Mat miniMat;
miniMat = imgray(rect);
Warning:In this case, miniMat is a subregion of imgray. This means that if you modify the former, you also modify the latter. Use miniMat.copyTo(anotherMat)to avoid this.
警告：在这种情况下，miniMat 是 imgray 的一个子区域。这意味着如果你修改前者，你也会修改后者。使用miniMat.copyTo(anotherMat)避免这种情况。
I hope it helped, Good luck
我希望它有帮助，祝你好运
