1、contourArea函数
函数作用
主要用于计算图像轮廓的面积
2、contourArea函数调用形式
C++: double contourArea(InputArray contour, bool oriented=false )
参数详解:
InputArray contour:输入的点,一般是图像的轮廓点
bool oriented=false:表示某一个方向上轮廓的的面积值,顺时针或者逆时针,一般选择默认false
3、opencv代码:
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include
#include
#include
using namespace cv;
using namespace std;
Mat src; Mat src_gray;
int thresh = 100;
int max_thresh = 255;
RNG rng(12345);
/// 函数声明
void thresh_callback(int, void*);
/** @主函数 */
int main(int argc, char** argv)
{
/// 读入原图像, 返回3通道图像数据
src = imread("D:6.jpg", 1);
/// 把原图像转化成灰度图像并进行平滑
cvtColor(src, src_gray, CV_BGR2GRAY);
blur(src_gray, src_gray, Size(3, 3));
/// 创建新窗口
char* source_window = "Source";
namedWindow(source_window, CV_WINDOW_AUTOSIZE);
imshow(source_window, src);
createTrackbar(" Canny thresh:", "Source", &thresh, max_thresh, thresh_callback);
thresh_callback(0, 0);
waitKey(0);
return(0);
}
/** @thresh_callback 函数 */
void thresh_callback(int, void*)
{
Mat canny_output;
vector > contours;
vector hierarchy;
/// 使用Canndy检测边缘
Canny(src_gray, canny_output, thresh, thresh * 2, 3);
/// 找到轮廓
findContours(canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));
/// 计算矩
vector mu(contours.size());
for (int i = 0; i < contours.size(); i++)
{
mu[i] = moments(contours[i], false);
}
/// 计算中心矩:
vector mc(contours.size());
for (int i = 0; i < contours.size(); i++)
{
mc[i] = Point2f(mu[i].m10 / mu[i].m00, mu[i].m01 / mu[i].m00);
}
/// 绘制轮廓
Mat drawing = Mat::zeros(canny_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, i, color, 2, 8, hierarchy, 0, Point());
circle(drawing, mc[i], 4, color, -1, 8, 0);
}
/// 显示到窗口中
namedWindow("Contours", CV_WINDOW_AUTOSIZE);
imshow("Contours", drawing);
/// 通过m00计算轮廓面积并且和OpenCV函数比较
printf("\t Info: Area and Contour Length \n");
for (int i = 0; i< contours.size(); i++)
{
printf(" * Contour[%d] - Area (M_00) = %.2f - Area OpenCV: %.2f - Length: %.2f \n", i, mu[i].m00, contourArea(contours[i]), arcLength(contours[i], true));
Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
drawContours(drawing, contours, i, color, 2, 8, hierarchy, 0, Point());
circle(drawing, mc[i], 4, color, -1, 8, 0);
}
}