findContours 发现边缘
cv::findContours(
InputOutputArray binImg,
OutputArrayOfArrays contours,
OutputArray, hierachy
int mode,
int method,
Point offset=Point()
)
drawContours 绘制边缘
drawContours(
InputOutputArray binImg,
OutputArrayOfArrays contours,
Int contourIdx
const Scalar & color,
int thickness,
int lineType ,
InputArray hierarchy,
int maxlevel,
Point offset=Point()
大致流程
- 输入图像转为灰度图像cvtColor
- 一系列降噪处理
- 一系列图像的增强
- 一系列阈值处理
- 使用Canny进行边缘提取,得到二值图像
- 使用findContours寻找轮廓
- 使用drawContours绘制轮廓
示例
#include <opencv2/opencv.hpp>
#include <iostream>
#include <math.h>
using namespace std;
using namespace cv;
Mat src, dst;
const char* output_win = "findcontours-demo";
int threshold_value = 100;
int threshold_max = 255;
RNG rng;
void Demo_Contours(int, void*);
int main(int argc, char** argv) {
src = imread("D:/vcprojects/images/happyfish.png");
if (src.empty()) {
printf("could not load image...\n");
return -1;
}
namedWindow("input-image");
namedWindow(output_win);
imshow("input-image", src);
cvtColor(src, src, CV_BGR2GRAY);
const char* trackbar_title = "Threshold Value:";
createTrackbar(trackbar_title, output_win, &threshold_value, threshold_max, Demo_Contours);
Demo_Contours(0, 0);
waitKey(0);
return 0;
}
void Demo_Contours(int, void*) {
Mat canny_output;
vector<vector<Point>> contours;
vector<Vec4i> hierachy;
Canny(src, canny_output, threshold_value, threshold_value * 2, 3, false);
findContours(canny_output, contours, hierachy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));
dst = Mat::zeros(src.size(), CV_8UC3);
RNG rng(12345);
for (size_t i = 0; i < contours.size(); i++) {
Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
drawContours(dst, contours, i, color, 2, 8, hierachy, 0, Point(0, 0));
}
imshow(output_win, dst);
}