【OpenCV3】图像轮廓查找与绘制——cv::findContours()与cv::drawContours()详解【轮廓】 - 轮廓

OpenCV3 图像轮廓 图像轮廓查找与绘制 findContours() drawContours()

OpenCV3之——查找并绘制轮廓findContours()和drawContours()，我们先来看看下面的基础示例：

#include
using namespace cv;
using namespace std;
int main() {
 Mat srcImage = imread("1.jpg", 0);
 imshow("原始图", srcImage);
 
 Mat dstImage = Mat::zeros(srcImage.rows, srcImage.cols, CV_8UC3);
 srcImage = srcImage > 119;//srcImage取大于阈值119的那部分
 imshow("取阈值后的原始图", srcImage);
 
 //定义轮廓和层次结构
 vector> contours;
 vector hierarchy;
 
 findContours(srcImage, contours, hierarchy, RETR_CCOMP, CHAIN_APPROX_SIMPLE);
 
 int index = 0;
 for (; index >= 0; index = hierarchy[index][0]) {
  Scalar color(rand() & 255, rand() & 255, rand() & 255);
  drawContours(dstImage, contours, index, color, CV_FILLED, 8, hierarchy);
 }
 
 imshow("轮廓图", dstImage);
 waitKey(0);
 return 0;
}
运行效果如下图：

再看下综合示例：

#include
#include
using namespace std;
using namespace cv;
 
#define WINDOW_NAME1 "原始窗口"
#define WINDOW_NAME2 "轮廓图"
 
//全局变量声明
Mat g_srcImage;
Mat g_grayImage;
int g_nThresh = 80;
int g_nThresh_max = 255;
RNG g_rng(12345);
Mat g_cannyMat_output;
vector> g_vContours;
vector g_vHierarchy;
//全局函数声明部分
void on_ThreshChange(int, void *);
 
int main() {
 system("color 1F");
 g_srcImage = imread("1.jpg", 1);
 if (!g_srcImage.data) {
  printf("图片读入错误！\n");
  return false;
 }
 cvtColor(g_srcImage, g_grayImage, COLOR_BGR2GRAY);
 blur(g_grayImage, g_grayImage, Size(3, 3));
 
 //创建窗口
 namedWindow(WINDOW_NAME1, WINDOW_AUTOSIZE);
 imshow(WINDOW_NAME1, g_srcImage);
 
 //创建滚动条并初始化
 createTrackbar("canny阈值", WINDOW_NAME1, &g_nThresh, g_nThresh_max, on_ThreshChange);
 on_ThreshChange(0, 0);
 waitKey(0);
 return 0;
}
 
void on_ThreshChange(int, void*) {
 //用Canny算子检测边缘
 Canny(g_grayImage, g_cannyMat_output, g_nThresh, g_nThresh * 2, 3);
 //寻找轮廓
 findContours(g_cannyMat_output, g_vContours, g_vHierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));
 //绘出轮廓
 Mat drawing = Mat::zeros(g_cannyMat_output.size(), CV_8UC3);
 for (int i = 0; i < g_vContours.size(); i++) {
  Scalar color = Scalar(g_rng.uniform(0, 255), g_rng.uniform(0, 255), g_rng.uniform(0, 255));
  drawContours(drawing, g_vContours, i, color, 2, 8, g_vHierarchy, 0, Point());
 }
 imshow(WINDOW_NAME2, drawing);
}
运行效果如下图：