②OpenCV的5个经典例程

<二>经典例子

这一次这几个例子要我自己一下子写出来应该是不可能的，先主要感受以下OpenCV的一些有趣的功能吧。（溜走

（1）彩色目标跟踪：Camshift

①Cameshift算法：根据鼠标框区域的色度光谱来进行摄像头读入的视频目标追踪。
②代码和示例往往能够更生动形象的进行理解
注：代码来源于OpenCV官方例程，每个用户的下载里面都有，这里的代码文件名为：camshiftdemo.cpp。

#include <opencv2/core/utility.hpp>
#include "opencv2/video/tracking.hpp"
#include "opencv2/imgproc.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"

#include <iostream>
#include <ctype.h>

using namespace cv;
using namespace std;

Mat image;

bool backprojMode = false;
bool selectObject = false;
int trackObject = 0;
bool showHist = true;
Point origin;
Rect selection;
int vmin = 10, vmax = 256, smin = 30;

// User draws box around object to track. This triggers CAMShift to start tracking
static void onMouse(int event, int x, int y, int, void*)
{
	if (selectObject)
	{
		selection.x = MIN(x, origin.x);
		selection.y = MIN(y, origin.y);
		selection.width = std::abs(x - origin.x);
		selection.height = std::abs(y - origin.y);

		selection &= Rect(0, 0, image.cols, image.rows);
	}

	switch (event)
	{
	case EVENT_LBUTTONDOWN:
		origin = Point(x, y);
		selection = Rect(x, y, 0, 0);
		selectObject = true;
		break;
	case EVENT_LBUTTONUP:
		selectObject = false;
		if (selection.width > 0 && selection.height > 0)
			trackObject = -1;   // Set up CAMShift properties in main() loop
		break;
	}
}

string hot_keys =
"\n\nHot keys: \n"
"\tESC - quit the program\n"
"\tc - stop the tracking\n"
"\tb - switch to/from backprojection view\n"
"\th - show/hide object histogram\n"
"\tp - pause video\n"
"To initialize tracking, select the object with mouse\n";

static void help()
{
	cout << "\nThis is a demo that shows mean-shift based tracking\n"
		"You select a color objects such as your face and it tracks it.\n"
		"This reads from video camera (0 by default, or the camera number the user enters\n"
		"Usage: \n"
		"   ./camshiftdemo [camera number]\n";
	cout << hot_keys;
}

const char* keys =
{
	"{help h | | show help message}{@camera_number| 0 | camera number}"
};

int main(int argc, const char** argv)
{
	VideoCapture cap;
	Rect trackWindow;
	int hsize = 16;
	float hranges[] = { 0,180 };
	const float* phranges = hranges;
	CommandLineParser parser(argc, argv, keys);
	if (parser.has("help"))
	{
		help();
		return 0;
	}
	int camNum = parser.get<int>(0);
	cap.open(camNum);

	if (!cap.isOpened())
	{
		help();
		cout << "***Could not initialize capturing...***\n";
		cout << "Current parameter's value: \n";
		parser.printMessage();
		return -1;
	}
	cout << hot_keys;
	namedWindow("Histogram", 0);
	namedWindow("CamShift Demo", 0);
	setMouseCallback("CamShift Demo", onMouse, 0);
	createTrackbar("Vmin", "CamShift Demo", &vmin, 256, 0);
	createTrackbar("Vmax", "CamShift Demo", &vmax, 256, 0);
	createTrackbar("Smin", "CamShift Demo", &smin, 256, 0);

	Mat frame, hsv, hue, mask, hist, histimg = Mat::zer