OpenCV的Rect矩形类用法

摘自 https://blog.csdn.net/kh1445291129/article/details/51149849

//如果创建一个Rect对象rect(100, 50, 50, 100)，那么rect会有以下几个功能：

rect.area(); //返回rect的面积 5000

rect.size(); //返回rect的尺寸 [50 × 100]

rect.tl(); //返回rect的左上顶点的坐标 [100, 50]

rect.br(); //返回rect的右下顶点的坐标 [150, 150]

rect.width(); //返回rect的宽度 50

rect.height(); //返回rect的高度 100

rect.contains(Point(x, y)); //返回布尔变量，判断rect是否包含Point(x, y)点

//还可以求两个矩形的交集和并集

rect = rect1 & rect2;

rect = rect1 | rect2;

//还可以对矩形进行平移和缩放

rect = rect + Point(-100, 100); //平移，也就是左上顶点的x坐标-100，y坐标+100

rect = rect + Size(-100, 100); //缩放，左上顶点不变，宽度-100，高度+100

//还可以对矩形进行对比，返回布尔变量

rect1 == rect2;

rect1 != rect2;

//OpenCV里貌似没有判断rect1是否在rect2里面的功能，所以自己写一个吧

bool isInside(Rect rect1, Rect rect2)

{

return (rect1 == (rect1&rect2));

}

//OpenCV貌似也没有获取矩形中心点的功能，还是自己写一个

Point getCenterPoint(Rect rect)

{

Point cpt;

cpt.x = rect.x + cvRound(rect.width/2.0);

cpt.y = rect.y + cvRound(rect.height/2.0);

return cpt;

}

//围绕矩形中心缩放

Rect rectCenterScale(Rect rect, Size size)

{

rect = rect + size;

Point pt;

pt.x = cvRound(size.width/2.0);

pt.y = cvRound(size.height/2.0);

return (rect-pt);

}

Opencv 使用Rect选取与设置窗口ROI

文章链接： http://blog.csdn.net/yhl_leo/article/details/50593825

首先看一下Rect对象的定义：

typedef Rect_<int> Rect;

再看Rect_的定义：

/*!The 2D up-right rectangle classThe class represents a 2D rectangle with coordinates of the specified data type.Normally, cv::Rect ~ cv::Rect_<int> is used.
*/
template<typename _Tp> class Rect_
{
public:typedef _Tp value_type;//! various constructorsRect_();Rect_(_Tp _x, _Tp _y, _Tp _width, _Tp _height);Rect_(const Rect_& r);Rect_(const CvRect& r);Rect_(const Point_<_Tp>& org, const Size_<_Tp>& sz);Rect_(const Point_<_Tp>& pt1, const Point_<_Tp>& pt2);Rect_& operator = ( const Rect_& r );//! the top-left cornerPoint_<_Tp> tl() const;//! the bottom-right cornerPoint_<_Tp> br() const;//! size (width, height) of the rectangleSize_<_Tp> size() const;//! area (width*height) of the rectangle_Tp area() const;//! conversion to another data typetemplate<typename _Tp2> operator Rect_<_Tp2>() const;//! conversion to the old-style CvRectoperator CvRect() const;//! checks whether the rectangle contains the pointbool contains(const Point_<_Tp>& pt) const;_Tp x, y, width, height; //< the top-left corner, as well as width and height of the rectangle
};

从上面的定义至少可以发现两点：

一，类Rect_的类模板中的数据类型_Tp在Rect_<int>中被指定为整型；

二，从Rect_的构造函数可以看出，其形参列表一共有6种形式：

Rect_()，形参列表为空，即定义一个空窗口（默认值为：x=y=width=height=0）；
Rect_(_Tp _x, _Tp _y, _Tp _width, _Tp _height)，定义一个左上角点坐标为(_x, _y)的_width*_height矩形窗口；
Rect_(const Rect_& r)，使用其他的Rect_对象初始化；
Rect_(const CvRect& r)，使用CvRect对象初始化；
Rect_(const Point_<_Tp>& org, const Size_<_Tp>& sz)，分别将位置坐标(_x, _y)和窗口大小(_width, _height)用Point_和Size_对象初始化；
Rect_(const Point_<_Tp>& pt1, const Point_<_Tp>& pt2)，分别将坐标位置(_x, _y)和窗口大小(_width, _height)用Point_和Point_对象初始化。

在OpenCV库中，图像像素坐标与所在行列数的对应关系为：x -> col, y -> row, width -> cols, height -> rows

下面给出一段代码，基本可以把Rect的常见用法涵盖：

Mat image = imread("C:\\Users\\Leo\\Desktop\\lena.jpg");
Rect rect1(256, 256, 128, 128);
Rect rect2(224, 224, 128, 128);Mat roi1;
image(rect1).copyTo(roi1); // copy the region rect1 from the image to roi1
imshow("1", roi1);
waitKey(0);Mat roi2;
image(rect2).copyTo(roi2); // copy the region rect2 from the image to roi2
imshow("2", roi2);
waitKey(0);cv::Rect rect3 = rect1&rect2; // intersection of the two sets
Mat roi3;
image(rect3).copyTo(roi3);
imshow("3", roi3);
waitKey(0);Rect rect4 = rect1|rect2; // union of the two sets (the minimum bounding rectangle)
Mat roi4;
image(rect4).copyTo(roi4);
imshow("4", roi4);
waitKey(0);Rect rect5(10, 10, 128, 128);
roi1.copyTo(image(rect5)); // copy the region rect1 to the designated region in the image
imshow("5", image);
waitKey(0);

结果为：

vector<Rect> 使用

vector<vector<Point> >

https://docs.opencv.org/2.4/doc/tutorials/imgproc/shapedescriptors/bounding_rects_circles/bounding_rects_circles.html#bounding-rects-circles

Creating Bounding boxes and circles for contours

Goal

In this tutorial you will learn how to:

Use the OpenCV function boundingRect
Use the OpenCV function minEnclosingCircle

Theory

Code

This tutorial code’s is shown lines below. You can also download it from here

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>using namespace cv;
using namespace std;Mat src; Mat src_gray;
int thresh = 100;
int max_thresh = 255;
RNG rng(12345);/// Function header
void thresh_callback(int, void* );/** @function main */
int main( int argc, char** argv )
{/// Load source image and convert it to graysrc = imread( argv[1], 1 );/// Convert image to gray and blur itcvtColor( src, src_gray, CV_BGR2GRAY );blur( src_gray, src_gray, Size(3,3) );/// Create Windowchar* source_window = "Source";namedWindow( source_window, CV_WINDOW_AUTOSIZE );imshow( source_window, src );createTrackbar( " Threshold:", "Source", &thresh, max_thresh, thresh_callback );thresh_callback( 0, 0 );waitKey(0);return(0);
}/** @function thresh_callback */
void thresh_callback(int, void* )
{Mat threshold_output;vector<vector<Point> > contours;vector<Vec4i> hierarchy;/// Detect edges using Thresholdthreshold( src_gray, threshold_output, thresh, 255, THRESH_BINARY );/// Find contoursfindContours( threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );/// Approximate contours to polygons + get bounding rects and circlesvector<vector<Point> > contours_poly( contours.size() );vector<rect> boundRect( contours.size() );vector<Point2f>center( contours.size() );vector<float>radius( contours.size() );for( int i = 0; i < contours.size(); i++ ){ approxPolyDP( Mat(contours[i]), contours_poly[i], 3, true );boundRect[i] = boundingRect( Mat(contours_poly[i]) );minEnclosingCircle( (Mat)contours_poly[i], center[i], radius[i] );}/// Draw polygonal contour + bonding rects + circlesMat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );for( int i = 0; i< contours.size(); i++ ){Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );drawContours( drawing, contours_poly, i, color, 1, 8, vector<Vec4i>(), 0, Point() );rectangle( drawing, boundRect[i].tl(), boundRect[i].br(), color, 2, 8, 0 );circle( drawing, center[i], (int)radius[i], color, 2, 8, 0 );}/// Show in a windownamedWindow( "Contours", CV_WINDOW_AUTOSIZE );imshow( "Contours", drawing );
}

原文地址：https://blog.csdn.net/KYJL888/article/details/82217192

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OpenCV的Rect矩形类简介和使用