文章目录
-
- [1. 使用矩形将图像中某个区域置为黑色](#1. 使用矩形将图像中某个区域置为黑色)
- [2. cv::Rect 类介绍](#2. cv::Rect 类介绍)
1. 使用矩形将图像中某个区域置为黑色
推荐参考博客:OpenCV实现将任意形状ROI区域置黑(多边形区域置黑)
比较常用的是使用 Rect 矩形实现该功能,代码如下:
cpp
#include <opencv2\opencv.hpp>
int main() {
std::string filePath = "img.png";
cv::Mat img = cv::imread(filePath);
//创建矩形
int x = img.cols / 2; // x 对应列坐标
int y = img.rows / 2; // y 对应行坐标
int width = 150;
int height = 80;
cv::Rect rect(x, y, width, height);
//将矩形贴到img中,并将矩形区域置为黑色
cv::Mat subImg = img(rect);
subImg.setTo(0);
cv::imwrite("img_rect.png", img);
return 0;
}
效果如下:
2. cv::Rect 类介绍
推荐参考博客:OpenCV 中 cv::Rect 矩形类用法
cv::Rect 用于创建矩形,API 参数如下:
bash
int x; // 左上角 x 坐标,对应列坐标
int y; // 左上角 y 坐标,对应列坐标
int width; // 宽
int height; // 高
源码如下:
cpp
template<typename _Tp> class Rect_
{
public:
typedef _Tp value_type;
//! default constructor
Rect_();
Rect_(_Tp _x, _Tp _y, _Tp _width, _Tp _height);
Rect_(const Rect_& r);
Rect_(Rect_&& r) CV_NOEXCEPT;
Rect_(const Point_<_Tp>& org, const Size_<_Tp>& sz);
Rect_(const Point_<_Tp>& pt1, const Point_<_Tp>& pt2);
Rect_& operator = ( const Rect_& r );
Rect_& operator = ( Rect_&& r ) CV_NOEXCEPT;
//! the top-left corner
Point_<_Tp> tl() const;
//! the bottom-right corner
Point_<_Tp> br() const;
//! size (width, height) of the rectangle
Size_<_Tp> size() const;
//! area (width*height) of the rectangle
_Tp area() const;
//! true if empty
bool empty() const;
//! conversion to another data type
template<typename _Tp2> operator Rect_<_Tp2>() const;
//! checks whether the rectangle contains the point
bool contains(const Point_<_Tp>& pt) const;
_Tp x; //!< x coordinate of the top-left corner
_Tp y; //!< y coordinate of the top-left corner
_Tp width; //!< width of the rectangle
_Tp height; //!< height of the rectangle
};
typedef Rect_<int> Rect2i;
typedef Rect_<float> Rect2f;
typedef Rect_<double> Rect2d;
typedef Rect2i Rect;