• 26、【opencv入门】轮廓查找与绘制(4)——正外接矩形


    一、简介

    1、使用特定形状的轮廓包围

      在实际应用中, 经常会有将检测到的轮廓用多边形表示出来的需求, 提取包围轮廓的多边形也方便我们做进一步分析, 轮廓包围主要有一下几种: 轮廓外接矩形、轮廓最小外接矩形(旋转)、轮廓最小包围圆形、轮廓拟合椭圆、轮廓逼近多边形曲线

    2、轮廓外接矩形 --- boundingRect()

    1 CV_EXPORTS_W Rect boundingRect(InputArray points);

      points: 输入的二维点集, 可以填Mat类型或std::vector

      返回值: Rect类矩形对象

    示例:

     1 vector<Rect> boundRect(contours.size());//定义外接矩形集合
     2 int x0 = 0, y0 = 0, w0 = 0, h0 = 0;
     3 for(int i = 0; i < contours.size(); i++)
     4 {
     5     drawContours(dstImg, contours, i, Scalar(0, 0, 255), 2, 8);
     6     boundRect[i] = boundingRect(Mat(contours[i]));
     7     x0 = boundRect[i].x;
     8     y0 = boundRect[i].y;
     9     w0 = boundRect[i].width;
    10     h0 = boundRect[i].height;
    11     
    12     rectangle(dstImg, Point(x0, y0), Point(x0 + w0, y0 + h0), Scalar(0, 255, 0), 2, 8);
    13 }

    二、外接矩形的查找绘制

     1 //外接矩形的查找绘制
     2 #include "opencv2/opencv.hpp"
     3 
     4 using namespace cv;
     5 
     6 int main()
     7 {
     8     //外接矩形的查找绘制
     9     Mat srcImg =imread("2.jpg");
    10     imshow("src",srcImg);
    11     Mat dstImg = srcImg.clone();  //原图备份
    12     cvtColor(srcImg, srcImg, CV_BGR2GRAY); //转为灰度图
    13     threshold(srcImg, srcImg, 100, 255, CV_THRESH_BINARY); //二值化
    14 
    15     vector<vector<Point>> contours;  
    16     vector<Vec4i> hierarcy;
    17     findContours(srcImg, contours, hierarcy, CV_RETR_EXTERNAL, CHAIN_APPROX_NONE); //查找轮廓
    18     vector<Rect> boundRect(contours.size()); //定义外接矩形集合
    19     //drawContours(dstImg, contours, -1, Scalar(0, 0, 255), 2, 8);  //绘制轮廓
    20     int x0=0, y0=0, w0=0, h0=0;
    21     for(int i=0; i<contours.size(); i++)
    22     {
    23         boundRect[i] = boundingRect((Mat)contours[i]); //查找每个轮廓的外接矩形
    24         drawContours(dstImg, contours, i, Scalar(0, 0, 255), 2, 8);  //绘制轮廓
    25         x0 = boundRect[i].x;  //获得第i个外接矩形的左上角的x坐标
    26         y0 = boundRect[i].y; //获得第i个外接矩形的左上角的y坐标
    27         w0 = boundRect[i].width; //获得第i个外接矩形的宽度
    28         h0 = boundRect[i].height; //获得第i个外接矩形的高度
    29         rectangle(dstImg, Point(x0, y0), Point(x0+w0, y0+h0), Scalar(0, 255, 0), 2, 8); //绘制第i个外接矩形
    30     }
    31     imshow("boundRect", dstImg);
    32     waitKey(0); 
    33     return 0;
    34 }

    三、分割硬币轮廓并计数

     1 //分割硬币轮廓并计数
     2 #include "opencv2/opencv.hpp"
     3 #include<iostream>
     4 
     5 using namespace cv;
     6 using namespace std;
     7 
     8 int main()
     9 {
    10     //分割硬币轮廓
    11     Mat srcImg =imread("3.png");
    12     imshow("src", srcImg);
    13     Mat dstImg = srcImg.clone();  //原图备份
    14     cvtColor(srcImg, srcImg, CV_BGR2GRAY); //转为灰度图
    15     threshold(srcImg, srcImg, 100, 255, CV_THRESH_BINARY); //二值化
    16     Mat element = getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1)); //获得结构元素
    17     dilate(srcImg, srcImg, element); //膨胀操作
    18     imshow("dilate",srcImg);
    19 
    20     vector<vector<Point>> contours;  
    21     vector<Vec4i> hierarcy;
    22     findContours(srcImg, contours, hierarcy, CV_RETR_EXTERNAL, CHAIN_APPROX_NONE); //查找轮廓
    23     vector<Rect> boundRect(contours.size()); //定义外接矩形集合
    24     int x0=0, y0=0, w0=0, h0=0,num=0;
    25     for(int i=0; i<contours.size(); i++)
    26     {
    27         boundRect[i] = boundingRect((Mat)contours[i]); //查找每个轮廓的外接矩形
    28         drawContours(dstImg, contours, i, Scalar(0, 0, 255), 2, 8);  //绘制轮廓
    29         x0 = boundRect[i].x;  
    30         y0 = boundRect[i].y; 
    31         w0 = boundRect[i].width; 
    32         h0 = boundRect[i].height; 
    33         if(w0>30 && h0>30)//筛选
    34         {
    35             rectangle(dstImg, Point(x0, y0), Point(x0+w0, y0+h0), Scalar(0, 255, 0), 2, 8); //绘制第i个外接矩形
    36             num++;
    37         }
    38     }
    39     cout<<"硬币数量:"<<num;
    40     imshow("boundRect", dstImg);
    41     waitKey(0); 
    42     return 0;
    43 }

     四、简单车牌字符分隔

     1 //简单车牌字符分割
     2 #include "opencv2/opencv.hpp"
     3 
     4 using namespace cv;
     5 
     6 int main()
     7 {
     8     //---简单车牌字符分隔
     9     Mat srcImg =imread("12.jpg");
    10     Mat dstImg = srcImg.clone();  //原图备份
    11     medianBlur(srcImg, srcImg, 5);  //中值滤波
    12     cvtColor(srcImg, srcImg, CV_BGR2GRAY); //转为灰度图
    13     threshold(srcImg, srcImg, 100, 255, CV_THRESH_BINARY); //二值化
    14     imshow("threshold", srcImg);
    15     imwrite("F://car0.jpg", srcImg);
    16 
    17     vector<vector<Point>> contours;  
    18     vector<Vec4i> hierarcy;
    19     findContours(srcImg, contours, hierarcy, CV_RETR_TREE, CHAIN_APPROX_NONE); //查找所有轮廓
    20     vector<Rect> boundRect(contours.size()); //定义外接矩形集合
    21     int x0=0, y0=0, w0=0, h0=0;
    22     for(int i=0; i<contours.size(); i++)
    23     {
    24         boundRect[i] = boundingRect((Mat)contours[i]); //查找每个轮廓的外接矩形
    25         x0 = boundRect[i].x;  
    26         y0 = boundRect[i].y; 
    27         w0 = boundRect[i].width; 
    28         h0 = boundRect[i].height; 
    29         if(w0>srcImg.cols/12 && w0<srcImg.cols/5 && h0>srcImg.rows/6 && h0<srcImg.rows*5/6)
    30         {
    31             char pic_name[10];
    32             sprintf(pic_name, "F:\%d.bmp", i);
    33             Mat ROI = dstImg(Rect(x0, y0, w0, h0));
    34             imwrite(pic_name, ROI);
    35             rectangle(dstImg, Point(x0, y0), Point(x0+w0, y0+h0), Scalar(0, 255, 0), 2, 8); //绘制第i个外接矩形
    36         }
    37     }
    38     imshow("boundRect", dstImg);
    39     waitKey(0);
    40     return 0;
    41 }


     

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  • 原文地址:https://www.cnblogs.com/Long-w/p/9668497.html
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