opencv 6 圖像輪廓與圖像分割修復 1 查找並繪制輪廓 尋找物體的凸包

查找並繪制輪廓

尋找輪廓（findContours）函數

繪制輪廓（drawContours()函數）

基礎實例程序：輪廓查找

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

//-----------------------------------【main( )函數】--------------------------------------------

//		描述：控制台應用程序的入口函數，我們的程序從這里開始
//-------------------------------------------------------------------------------------------------
int main(int argc, char** argv)
{
	// 【1】載入原始圖，且必須以二值圖模式載入
	Mat srcImage = imread("1.jpg", 0);
	imshow("原始圖", srcImage);

	//【2】初始化結果圖
	Mat dstImage = Mat::zeros(srcImage.rows, srcImage.cols, CV_8UC3);

	//【3】srcImage取大於閾值119的那部分
	srcImage = srcImage > 119;
	imshow("取閾值后的原始圖", srcImage);

	//【4】定義輪廓和層次結構
	vector<vector<Point> > contours;
	vector<Vec4i> hierarchy;

	//【5】查找輪廓
	
	//此句代碼的OpenCV3版為：
	findContours(srcImage, contours, hierarchy, RETR_CCOMP, CHAIN_APPROX_SIMPLE);

	// 【6】遍歷所有頂層的輪廓， 以隨機顏色繪制出每個連接組件顏色
	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】顯示最后的輪廓圖
	imshow("輪廓圖", dstImage);

	waitKey(0);

}

綜合實例程序(加blur，canny和滑動條）：

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


//-----------------------------------【宏定義部分】-------------------------------------------- 
//		描述：定義一些輔助宏 
//------------------------------------------------------------------------------------------------ 
#define WINDOW_NAME1 "【原始圖窗口】"			//為窗口標題定義的宏 
#define WINDOW_NAME2 "【輪廓圖】"					//為窗口標題定義的宏 


//-----------------------------------【全局變量聲明部分】--------------------------------------
//		描述：全局變量的聲明
//-----------------------------------------------------------------------------------------------
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;


//-----------------------------------【全局函數聲明部分】--------------------------------------
//		描述：全局函數的聲明
//-----------------------------------------------------------------------------------------------
static void ShowHelpText();
void on_ThreshChange(int, void*);


//-----------------------------------【main( )函數】--------------------------------------------
//		描述：控制台應用程序的入口函數，我們的程序從這里開始執行
//-----------------------------------------------------------------------------------------------
int main(int argc, char** argv)
{
	//【0】改變console字體顏色
	system("color 1F");

	//【0】顯示歡迎和幫助文字
	ShowHelpText();

	// 加載源圖像
	g_srcImage = imread("1.jpg", 1);
	if (!g_srcImage.data) { printf("讀取圖片錯誤，請確定目錄下是否有imread函數指定的圖片存在~！ \n"); return false; }

	// 轉成灰度並模糊化降噪
	cvtColor(g_srcImage, g_grayImage, COLOR_BGR2GRAY);
	blur(g_grayImage, g_grayImage, Size(3, 3));

	// 創建窗口
	namedWindow(WINDOW_NAME1, WINDOW_AUTOSIZE);
	imshow(WINDOW_NAME1, g_srcImage);

	//創建滾動條並初始化
	createTrackbar("canny閾值", WINDOW_NAME1, &g_nThresh, g_nThresh_max, on_ThreshChange);
	on_ThreshChange(0, 0);

	waitKey(0);
	return(0);
}

//-----------------------------------【on_ThreshChange( )函數】------------------------------  
//      描述：回調函數
//----------------------------------------------------------------------------------------------  
void on_ThreshChange(int, void*)
{

	// 用Canny算子檢測邊緣
	Canny(g_grayImage, g_cannyMat_output, g_nThresh, g_nThresh * 2, 3);

	// 尋找輪廓
	findContours(g_cannyMat_output, g_vContours, g_vHierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));

	// 繪出輪廓
	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());
	}

	// 顯示效果圖
	imshow(WINDOW_NAME2, drawing);
}


//-----------------------------------【ShowHelpText( )函數】----------------------------------  
//      描述：輸出一些幫助信息  
//----------------------------------------------------------------------------------------------  
static void ShowHelpText()
{
	//輸出歡迎信息和OpenCV版本
	
	printf("\n\n\t\t\t   當前使用的OpenCV版本為：" CV_VERSION);
	printf("\n\n  ----------------------------------------------------------------------------\n");

	//輸出一些幫助信息  
	printf("\n\n\t歡迎來到【在圖形中尋找輪廓】示例程序~\n\n");
	printf("\n\n\t按鍵操作說明: \n\n"
		"\t\t鍵盤按鍵任意鍵- 退出程序\n\n"
		"\t\t滑動滾動條-改變閾值\n");
}

尋找物體的凸包

尋找凸包（convexHull()函數）

基礎示例程序：凸包檢測基礎

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

//-----------------------------------【ShowHelpText( )函數】----------------------------------
//          描述：輸出一些幫助信息
//----------------------------------------------------------------------------------------------
static void ShowHelpText()
{
	//輸出歡迎信息和OpenCV版本
	
	printf("\n\n\t\t\t   當前使用的OpenCV版本為：" CV_VERSION);
	printf("\n\n  ----------------------------------------------------------------------------\n");
	//輸出一些幫助信息
	printf("\n\t歡迎來到【凸包檢測】示例程序~\n\n");
	printf("\n\t按鍵操作說明: \n\n"
		"\t\t鍵盤按鍵【ESC】、【Q】、【q】- 退出程序\n\n"
		"\t\t鍵盤按鍵任意鍵 - 重新生成隨機點，並進行凸包檢測\n");

}


//--------------------------------------【main( )函數】-----------------------------------------
//          描述：控制台應用程序的入口函數，我們的程序從這里開始執行
//-----------------------------------------------------------------------------------------------
int main()
{
	//改變console字體顏色
	system("color 1F");

	//顯示幫助文字
	ShowHelpText();

	//初始化變量和隨機值
	Mat image(600, 600, CV_8UC3);
	RNG& rng = theRNG();

	//循環，按下ESC,Q,q鍵程序退出，否則有鍵按下便一直更新
	while (1)
	{
		//參數初始化
		char key;//鍵值
		int count = (unsigned)rng % 100 + 3;//隨機生成點的數量
		vector<Point> points; //點值

		//隨機生成點坐標
		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);
		}

		//檢測凸包
		vector<int> hull;
		convexHull(Mat(points), hull, true);

		//繪制出隨機顏色的點
		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);

		//准備參數
		int hullcount = (int)hull.size();//凸包的邊數
		Point point0 = points[hull[hullcount - 1]];//連接凸包邊的坐標點

		//繪制凸包的邊
		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;
		}

		//顯示效果圖
		imshow("凸包檢測示例", 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;
}

綜合實例程序：尋找和繪制物體的凸包

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


//-----------------------------------【宏定義部分】-------------------------------------------- 
//  描述：定義一些輔助宏 
//------------------------------------------------------------------------------------------------ 
#define WINDOW_NAME1 "【原始圖窗口】"					//為窗口標題定義的宏 
#define WINDOW_NAME2 "【效果圖窗口】"					//為窗口標題定義的宏 



//-----------------------------------【全局變量聲明部分】--------------------------------------
//  描述：全局變量的聲明
//-----------------------------------------------------------------------------------------------
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;


//-----------------------------------【全局函數聲明部分】--------------------------------------
//   描述：全局函數的聲明
//-----------------------------------------------------------------------------------------------

void on_ThreshChange(int, void*);


//-----------------------------------【main( )函數】------------------------------------------
//   描述：控制台應用程序的入口函數，我們的程序從這里開始執行
//-----------------------------------------------------------------------------------------------
int main()
{

	// 加載源圖像
	g_srcImage = imread("1.jpg", 1);

	// 將原圖轉換成灰度圖並進行模糊降
	cvtColor(g_srcImage, g_grayImage, COLOR_BGR2GRAY);
	blur(g_grayImage, g_grayImage, Size(3, 3));

	// 創建原圖窗口並顯示
	namedWindow(WINDOW_NAME1, WINDOW_AUTOSIZE);
	imshow(WINDOW_NAME1, g_srcImage);

	//創建滾動條
	createTrackbar(" 閾值:", WINDOW_NAME1, &g_nThresh, g_maxThresh, on_ThreshChange);
	on_ThreshChange(0, 0);//調用一次進行初始化

	waitKey(0);
	return(0);
}

//-----------------------------------【thresh_callback( )函數】----------------------------------  
//      描述：回調函數
//----------------------------------------------------------------------------------------------  
void on_ThreshChange(int, void*)
{
	// 對圖像進行二值化，控制閾值
	threshold(g_grayImage, g_thresholdImage_output, g_nThresh, 255, THRESH_BINARY);

	// 尋找輪廓
	findContours(g_thresholdImage_output, g_vContours, g_vHierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));

	// 遍歷每個輪廓，尋找其凸包
	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);
	}

	// 繪出輪廓及其凸包
	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());
	}

	// 顯示效果圖
	imshow(WINDOW_NAME2, drawing);
}

HSV學習鏈接https://blog.csdn.net/coldwindha/article/details/82080176