来自Mat图像的OpenCV子图像 [英] OpenCV sub-image from a Mat image

问题描述

可能重复：

了解openCV 2.4的感兴趣区域

我想从图像（Mat格式）获取子图像（由下面红色框所包围的子图像）。我如何做到这一点？

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?

这里是我迄今为止的进展：

here's my progress so far:

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);
}

推荐答案

（在你的情况下，轮廓对应于手）。
然后，计算此轮廓的边界矩形。
最后，从中创建一个新的矩阵头。

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.

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);

警告：在这种情况下，miniMat是imgray的子​​区域。这意味着如果你修改前者，你也修改后者。使用 miniMat.copyTo（anotherMat）可以避免这种情况。

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.

我希望它有帮助，
祝你好运

I hope it helped, Good luck

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