opencv 6 图像轮廓与图像分割修复 1 查找并绘制轮廓 寻找物体的凸包

查找并绘制轮廓

寻找轮廓（findContours）函数

绘制轮廓（drawContours()函数）

基础实例程序：轮廓查找

#include <opencv2/opencv.hpp>
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
using namespace cv;
using namespace std;

//-----------------------------------【main( )函数】--------------------------------------------

//		描述：控制台应用程序的入口函数，我们的程序从这里开始
//-------------------------------------------------------------------------------------------------
int main(int argc, char** argv)
{
	// 【1】载入原始图，且必须以二值图模式载入
	Mat srcImage = imread("1.jpg", 0);
	imshow("原始图", srcImage);

	//【2】初始化结果图
	Mat dstImage = Mat::zeros(srcImage.rows, srcImage.cols, CV_8UC3);

	//【3】srcImage取大于阈值119的那部分
	srcImage = srcImage > 119;
	imshow("取阈值后的原始图", srcImage);

	//【4】定义轮廓和层次结构
	vector<vector<Point> > contours;
	vector<Vec4i> hierarchy;

	//【5】查找轮廓
	
	//此句代码的OpenCV3版为：
	findContours(srcImage, contours, hierarchy, RETR_CCOMP, CHAIN_APPROX_SIMPLE);

	// 【6】遍历所有顶层的轮廓， 以随机颜色绘制出每个连接组件颜色
	int index = 0;
	for (; index >= 0; index = hierarchy[index][0])
	{
		Scalar color(rand() & 255, rand() & 255, rand() & 255);
		
		drawContours(dstImage, contours, index, color, FILLED, 8, hierarchy);
	}

	//【7】显示最后的轮廓图
	imshow("轮廓图", dstImage);

	waitKey(0);

}

综合实例程序(加blur，canny和滑动条）：

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
using namespace cv;
using namespace std;


//-----------------------------------【宏定义部分】-------------------------------------------- 
//		描述：定义一些辅助宏 
//------------------------------------------------------------------------------------------------ 
#define WINDOW_NAME1 "【原始图窗口】"			//为窗口标题定义的宏 
#define WINDOW_NAME2 "【轮廓图】"					//为窗口标题定义的宏 


//-----------------------------------【全局变量声明部分】--------------------------------------
//		描述：全局变量的声明
//-----------------------------------------------------------------------------------------------
Mat g_srcImage;
Mat g_grayImage;
int g_nThresh = 80;
int g_nThresh_max = 255;
RNG g_rng(12345);
Mat g_cannyMat_output;
vector<vector<Point>> g_vContours;
vector<Vec4i> g_vHierarchy;


//-----------------------------------【全局函数声明部分】--------------------------------------
//		描述：全局函数的声明
//-----------------------------------------------------------------------------------------------
static void ShowHelpText();
void on_ThreshChange(int, void*);


//-----------------------------------【main( )函数】--------------------------------------------
//		描述：控制台应用程序的入口函数，我们的程序从这里开始执行
//-----------------------------------------------------------------------------------------------
int main(int argc, char** argv)
{
	//【0】改变console字体颜色
	system("color 1F");

	//【0】显示欢迎和帮助文字
	ShowHelpText();

	// 加载源图像
	g_srcImage = imread("1.jpg", 1);
	if (!g_srcImage.data) { printf("读取图片错误，请确定目录下是否有imread函数指定的图片存在~！ 
"); return false; }

	// 转成灰度并模糊化降噪
	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);
}

//-----------------------------------【on_ThreshChange( )函数】------------------------------  
//      描述：回调函数
//----------------------------------------------------------------------------------------------  
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));//任意值
		drawContours(drawing, g_vContours, i, color, 2, 8, g_vHierarchy, 0, Point());
	}

	// 显示效果图
	imshow(WINDOW_NAME2, drawing);
}


//-----------------------------------【ShowHelpText( )函数】----------------------------------  
//      描述：输出一些帮助信息  
//----------------------------------------------------------------------------------------------  
static void ShowHelpText()
{
	//输出欢迎信息和OpenCV版本
	
	printf("

			   当前使用的OpenCV版本为：" CV_VERSION);
	printf("

  ----------------------------------------------------------------------------
");

	//输出一些帮助信息  
	printf("

	欢迎来到【在图形中寻找轮廓】示例程序~

");
	printf("

	按键操作说明: 

"
		"		键盘按键任意键- 退出程序

"
		"		滑动滚动条-改变阈值
");
}

寻找物体的凸包

寻找凸包（convexHull()函数）

基础示例程序：凸包检测基础

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <iostream>
using namespace cv;
using namespace std;

//-----------------------------------【ShowHelpText( )函数】----------------------------------
//          描述：输出一些帮助信息
//----------------------------------------------------------------------------------------------
static void ShowHelpText()
{
	//输出欢迎信息和OpenCV版本
	
	printf("

			   当前使用的OpenCV版本为：" CV_VERSION);
	printf("

  ----------------------------------------------------------------------------
");
	//输出一些帮助信息
	printf("
	欢迎来到【凸包检测】示例程序~

");
	printf("
	按键操作说明: 

"
		"		键盘按键【ESC】、【Q】、【q】- 退出程序

"
		"		键盘按键任意键 - 重新生成随机点，并进行凸包检测
");

}


//--------------------------------------【main( )函数】-----------------------------------------
//          描述：控制台应用程序的入口函数，我们的程序从这里开始执行
//-----------------------------------------------------------------------------------------------
int main()
{
	//改变console字体颜色
	system("color 1F");

	//显示帮助文字
	ShowHelpText();

	//初始化变量和随机值
	Mat image(600, 600, CV_8UC3);
	RNG& rng = theRNG();

	//循环，按下ESC,Q,q键程序退出，否则有键按下便一直更新
	while (1)
	{
		//参数初始化
		char key;//键值
		int count = (unsigned)rng % 100 + 3;//随机生成点的数量
		vector<Point> points; //点值

		//随机生成点坐标
		for (int i = 0; i < count; i++)
		{
			Point point;
			point.x = rng.uniform(image.cols / 4, image.cols * 3 / 4);
			point.y = rng.uniform(image.rows / 4, image.rows * 3 / 4);

			points.push_back(point);
		}

		//检测凸包
		vector<int> hull;
		convexHull(Mat(points), hull, true);

		//绘制出随机颜色的点
		image = Scalar::all(0);
		for (int i = 0; i < count; i++)
			circle(image, points[i], 3, Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255)), FILLED, LINE_AA);

		//准备参数
		int hullcount = (int)hull.size();//凸包的边数
		Point point0 = points[hull[hullcount - 1]];//连接凸包边的坐标点

		//绘制凸包的边
		for (int i = 0; i < hullcount; i++)
		{
			Point point = points[hull[i]];
			line(image, point0, point, Scalar(255, 255, 255), 2, LINE_AA);
			point0 = point;
		}

		//显示效果图
		imshow("凸包检测示例", image);

		//按下ESC,Q,或者q，程序退出
		key = (char)waitKey();
		if (key == 27 || key == 'q' || key == 'Q')
			break;
	}

	return 0;
}

综合实例程序：寻找和绘制物体的凸包

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
using namespace cv;
using namespace std;


//-----------------------------------【宏定义部分】-------------------------------------------- 
//  描述：定义一些辅助宏 
//------------------------------------------------------------------------------------------------ 
#define WINDOW_NAME1 "【原始图窗口】"					//为窗口标题定义的宏 
#define WINDOW_NAME2 "【效果图窗口】"					//为窗口标题定义的宏 



//-----------------------------------【全局变量声明部分】--------------------------------------
//  描述：全局变量的声明
//-----------------------------------------------------------------------------------------------
Mat g_srcImage; Mat g_grayImage;
int g_nThresh = 50;
int g_maxThresh = 255;
RNG g_rng(12345);
Mat srcImage_copy = g_srcImage.clone();
Mat g_thresholdImage_output;
vector<vector<Point> > g_vContours;
vector<Vec4i> g_vHierarchy;


//-----------------------------------【全局函数声明部分】--------------------------------------
//   描述：全局函数的声明
//-----------------------------------------------------------------------------------------------

void on_ThreshChange(int, void*);


//-----------------------------------【main( )函数】------------------------------------------
//   描述：控制台应用程序的入口函数，我们的程序从这里开始执行
//-----------------------------------------------------------------------------------------------
int main()
{

	// 加载源图像
	g_srcImage = imread("1.jpg", 1);

	// 将原图转换成灰度图并进行模糊降
	cvtColor(g_srcImage, g_grayImage, COLOR_BGR2GRAY);
	blur(g_grayImage, g_grayImage, Size(3, 3));

	// 创建原图窗口并显示
	namedWindow(WINDOW_NAME1, WINDOW_AUTOSIZE);
	imshow(WINDOW_NAME1, g_srcImage);

	//创建滚动条
	createTrackbar(" 阈值:", WINDOW_NAME1, &g_nThresh, g_maxThresh, on_ThreshChange);
	on_ThreshChange(0, 0);//调用一次进行初始化

	waitKey(0);
	return(0);
}

//-----------------------------------【thresh_callback( )函数】----------------------------------  
//      描述：回调函数
//----------------------------------------------------------------------------------------------  
void on_ThreshChange(int, void*)
{
	// 对图像进行二值化，控制阈值
	threshold(g_grayImage, g_thresholdImage_output, g_nThresh, 255, THRESH_BINARY);

	// 寻找轮廓
	findContours(g_thresholdImage_output, g_vContours, g_vHierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));

	// 遍历每个轮廓，寻找其凸包
	vector<vector<Point> >hull(g_vContours.size());
	for (unsigned int i = 0; i < g_vContours.size(); i++)
	{
		convexHull(Mat(g_vContours[i]), hull[i], false);
	}

	// 绘出轮廓及其凸包
	Mat drawing = Mat::zeros(g_thresholdImage_output.size(), CV_8UC3);
	for (unsigned 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, 1, 8, vector<Vec4i>(), 0, Point());
		drawContours(drawing, hull, i, color, 1, 8, vector<Vec4i>(), 0, Point());
	}

	// 显示效果图
	imshow(WINDOW_NAME2, drawing);
}

HSV学习链接https://blog.csdn.net/coldwindha/article/details/82080176