先看效果

直接上原始碼：

// change_img_size.cpp : 定義控制檯應用程式的入口點。
//


#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

#include <iostream>
#include <stdio.h>

using namespace cv;
using namespace std;

int main(int argc, char* argv[])
{
    Mat imgSrc = imread("d:\\image\\1.jpg",1);
    imshow("sourceImg", imgSrc);
    Mat img_gray;
    cvtColor(imgSrc, img_gray, CV_BGR2GRAY);
    threshold(img_gray, img_gray, 100, 255, CV_THRESH_BINARY_INV);
    imshow("thresholdImg", img_gray);
    vector<vector<cv::Point> > contours;
    vector<Vec4i> hierarchy;
    findContours(img_gray, contours, hierarchy,
        CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE );
    Mat img1;
    Mat img2;
    Mat img3;
    Mat img4;
    Mat img5;


    for(int i=0; i<contours.size();i++)
    {
        Rect rect = boundingRect(Mat(contours[i]));
        rectangle(imgSrc, rect.tl(), rect.br(),Scalar(255,0,0));
        Mat roi = imgSrc(rect);
        switch(i)
        {
        case 1:
            roi.convertTo(img1, roi.type());
        case 4:
            roi.convertTo(img2, roi.type());
        case 5:
            roi.convertTo(img3, roi.type());
        case 7:
            roi.convertTo(img4, roi.type());
        case 8:
            roi.convertTo(img5, roi.type());
            
        }
    }
    imshow("img1",img1);
    imshow("img2",img2);
    imshow("img3",img3);
    imshow("img4",img4);
    imshow("img5",img5);
    imshow("contoursImg", imgSrc);


    
    waitKey(0);

    return 0;
}