轮廓特征属性及应用(四)——正外接矩形
1.轮廓正外接矩形——boundingRect（）
2.完成了三个小应用：正外接矩形的查找绘制、分割硬币轮廓、简单车牌字符分割
先上ppt：
代码：
正外接矩形的查找绘制：
///正外接矩形的查找绘制
#include "opencv2/opencv.hpp"
using namespace cv;
#include <iostream>
using namespace std;
int main()
{
//1.查找轮廓
//1.1查找轮廓前的预处理（灰度图，阈值化）
Mat srcImg = imread("12.jpg",CV_LOAD_IMAGE_COLOR);
imshow("srcImg", srcImg);
Mat copyImg = srcImg.clone();
cvtColor(srcImg,srcImg,CV_BGR2GRAY);
threshold(srcImg,srcImg,100,255,CV_THRESH_BINARY);
imshow("threshold",srcImg);
vector <vector<Point>> contours;
vector<Vec4i> hierarcy;//没用到
//1.2查找轮廓
findContours(srcImg,contours,CV_RETR_EXTERNAL,CV_CHAIN_APPROX_NONE);//最外层轮廓
//1.3绘制所有轮廓
drawContours(copyImg,contours,-1,Scalar(0,255,0),1,8);
//2.由轮廓确定正外接矩形
int width = 0;
int height = 0;
int x = 0;
int y = 0;
//2.1 定义Rect类型的vector容器boundRect存放正外接矩形，初始化大小为contours.size()即轮廓个数
vector<Rect> boundRect(contours.size());
//2.2 遍历每个轮廓
for (int i = 0; i < contours.size(); i++)
{
//2.3由轮廓（点集）确定出正外接矩形
boundRect[i] = boundingRect(Mat(contours[i]));
//2.4获得正外接矩形的左上角坐标及宽高
width = boundRect[i].width;
height = boundRect[i].height;
x = boundRect[i].x;
y = boundRect[i].y;
//2.5用画矩形方法绘制正外接矩形
rectangle(copyImg,Rect(x,y,width,height),Scalar(0,0,255),1,8);
}
imshow("轮廓和正外接矩形", copyImg);
waitKey(0);
return 0;
}
运行结果：
分割硬币轮廓：
///分割硬币轮廓
#include "opencv2/opencv.hpp"
using namespace cv;
#include <iostream>
using namespace std;
int main()
{
//1.查找轮廓
//1.1查找轮廓前的预处理（灰度图，阈值化）
Mat srcImg = imread("33.png",CV_LOAD_IMAGE_COLOR);
imshow("srcImg", srcImg);
Mat copyImg = srcImg.clone();
cvtColor(srcImg,srcImg,CV_BGR2GRAY);
threshold(srcImg,srcImg,100,255,CV_THRESH_BINARY);
imshow("threshold",srcImg);
//*1.2增加了膨胀和腐蚀
//因为有一个轮廓有断点，导致外接矩形是两个小的而不是一个整的，故要膨胀，将断点连起来
//1.2.1定义kernel
Mat kernel = getStructuringElement(MORPH_RECT,Size(5,5),Point(-1,-1));
//1.2.2膨胀
dilate(srcImg,srcImg,kernel,Point(-1,-1));
//1.2.3腐蚀
erode(srcImg,srcImg,kernel,Point(-1,-1));
imshow("膨胀和腐蚀", srcImg);
//1.3查找轮廓
vector <vector<Point>> contours;
vector<Vec4i> hierarcy;//没用到
findContours(srcImg,contours,CV_RETR_EXTERNAL,CV_CHAIN_APPROX_NONE);//最外层轮廓
//1.4绘制所有轮廓
drawContours(copyImg,contours,-1,Scalar(0,255,0),1,8);
//2.由轮廓确定正外接矩形
int width = 0;
int height = 0;
int x = 0;
int y = 0;
//2.1 定义Rect类型的vector容器boundRect存放正外接矩形，初始化大小为contours.size()即轮廓个数
vector<Rect> boundRect(contours.size());
//2.2 遍历每个轮廓
for (int i = 0; i < contours.size(); i++)
{
//2.3由轮廓（点集）确定出正外接矩形
boundRect[i] = boundingRect(Mat(contours[i]));
//2.4获得正外接矩形的左上角坐标及宽高
width = boundRect[i].width;
height = boundRect[i].height;
x = boundRect[i].x;
y = boundRect[i].y;
//*2.5 对正外接矩形进行筛选（过滤掉小的）
if (width>40 && height > 40)
{
//2.6用画矩形方法绘制正外接矩形
rectangle(copyImg, Rect(x, y, width, height), Scalar(0, 0, 255), 1, 8);
}
}
imshow("轮廓和正外接矩形", copyImg);
waitKey(0);
return 0;
}
运行结果：
简单车牌字符分割：
///简单车牌字符分割
#include "opencv2/opencv.hpp"
using namespace cv;
#include <iostream>
using namespace std;
int main()
{
//1.查找轮廓
//1.1查找轮廓前的预处理（灰度图，阈值化）
Mat srcImg = imread("Car.jpg", CV_LOAD_IMAGE_COLOR);
imshow("srcImg", srcImg);
Mat copyImg = srcImg.clone();
cvtColor(srcImg, srcImg, CV_BGR2GRAY);
threshold(srcImg, srcImg, 100, 255, CV_THRESH_BINARY);
imshow("threshold", srcImg);
//1.2查找轮廓
vector <vector<Point>> contours;
vector<Vec4i> hierarcy;//没用到
findContours(srcImg, contours, CV_RETR_LIST, CV_CHAIN_APPROX_NONE);//所有轮廓
//1.3绘制所有轮廓
drawContours(copyImg, contours, -1, Scalar(0, 255, 0), 1, 8);
//2.由轮廓确定正外接矩形
int width = 0;
int height = 0;
int x = 0;
int y = 0;
//2.1 定义Rect类型的vector容器boundRect存放正外接矩形，初始化大小为contours.size()即轮廓个数
vector<Rect> boundRect(contours.size());
//2.2 遍历每个轮廓
for (int i = 0; i < contours.size(); i++)
{
//2.3由轮廓（点集）确定出正外接矩形
boundRect[i] = boundingRect(Mat(contours[i]));
//2.4获得正外接矩形的左上角坐标及宽高
width = boundRect[i].width;
height = boundRect[i].height;
x = boundRect[i].x;
y = boundRect[i].y;
//*2.5 对正外接矩形进行筛选（过滤掉过小及过大的）
if (width>(1.0 / 12)*srcImg.cols && width<(1.0 / 7)*srcImg.cols
&&height >(1.0 / 6)*srcImg.rows&& height < (5.0 / 6)*srcImg.rows)
{
//2.6用画矩形方法绘制正外接矩形
rectangle(copyImg, Rect(x, y, width, height), Scalar(0, 0, 255), 1, 8);
//*2.7 通过ROI保存分割出的车牌字符
//2.7.1 定义ROI
Mat ROI = copyImg(Rect(x,y,width,height));
//2.7.2 通过sprintf格式化文件存储名name
char name[20] = {0};
sprintf(name,"E:\\temp\\%d.jpg",i);
//2.7.3 写ROI到本地
imwrite(name,ROI);
}
}
imshow("轮廓和正外接矩形", copyImg);
waitKey(0);
return 0;
}
运行结果：
