OpenCV学习(十一)之随机数生成器RNG

超、凢脫俗 2022-08-05 20:28 555阅读 0赞

OpenCV中C++的RNG类可以压缩一个64位的i整数并可以得到scalar和array的随机数。目前的版本支持均匀分布随机数和Gaussian分布随机数。随机数的产生采用的是Multiply-With-Carry算法和Ziggurat算法。其构造函数的初始化可以传入一个64位的整型参数作为随机数产生器的初值。next可以取出下一个随机数，uniform函数可以返回指定范围的随机数，gaussian函数返回一个高斯随机数，fill则用随机数填充矩阵等等。

以下测试程序分别测试了RNG类中各个函数的用法以及解释了各个参数的意思，重点都在注释里。此外测试程序后半部分也大概介绍了c版本的随机数产生器，如cvRNG、cvRandArr、cvRandInt、cvRandReal等。由于理解还能力有限，个别函数还是不太清楚。

实验环境：VS2010 + OpenCV2.4.9.0

#include <iostream>
    #include "cv.h"
    #include "highgui.h"
    
    using namespace cv;
    using namespace std;
    
    int main(int argc,char** argv)
    {
    	RNG rng;
    	// always produces 0
    	//RNG::uniform(int,int)
    	//因为只会去整数，所以只产生0
    	double a = rng.uniform(0,1);
    	
    	//produces double from[0,1)
    	double a1 = rng.uniform((double)0,(double)1);
    
    	//produces float from[0,1)
    	double b = rng.uniform(0.f,1.f);
    
    	//produces double from[0,1)
    	double c = rng.uniform(0.,1.);
    
    	//may cause compiler error because of ambiguity:
    	//RNG:: uniform(0,(int)0.999999) ? or RNG::unigorm((double)0,0.999999)
    	//double d = rng.uniform(0,0.999999);所以先注释起来吧 O(∩_∩)O
    	cout << "a = " << a << endl;
    	cout << "a1 = " << a1 << endl;
    	cout << "b = " << b << endl;
    	cout << "c = " << c << endl;
    	//cout << "d = " << d << endl;
    
    	/*-------- returns the next random number sampled from the Gaussian distribution-------
    	*	double RNG:: gaussian( double sigma)
    	*	sigma – standard deviation(标准差) of the distribution
    	------------------------------------------------------------------------------------*/
    	double g = rng.gaussian(2);
    	cout << "g = " << g << endl;
    
    	/*-------- returns the next random number(还不理解这个“下一个”是指什么？) -------------------
    	*	unsigned int RNG:: next()
    	*	The method updates the state using the MWC algorithm and
    		returns the next 32-bit random number
    	------------------------------------------------------------------------------------*/
    	int n = rng.next();
    	cout << "n = " << n << endl;
    
    	/*-------- RNG::operator T returns the next random number of the specified type ---------
    	*	RNG:: operator uchar()
    	*	RNG:: operator schar()
    	*	RNG:: operator ushort()
    	*	RNG:: operator short int()
    	*	RNG:: operator int()
    	*	RNG:: operator unsigned int()
    	*	RNG:: operator float()
    	*	RNG:: operator double()
    	*	返回指定类型的下一个随机数。对于int型，返回可用数据类型范围内的随机数，对于float型，
    		返回[0,1)范围的随机数
    	------------------------------------------------------------------------------------*/
    	int n1 = rng.operator int();
    	cout << "n1 = " << n1 << endl;
    
    	float f = rng.operator float();
    	cout << "f = " << f << endl;
    
    	/*-------- RNG::operator () returns the next random number -----------------------
    	*	unsigned int RNG:: operator() ()  == RNG::next() 两个函数相同
    	*	unsigned int RNG:: operator() (unsigned int N) 注意括号
    	*	return the result in the range [0,N)
    	------------------------------------------------------------------------------------*/
    	int o = rng.operator ()();
    	int o1 = rng.operator() (50);
    	cout << "o = " << o << endl << "o1 = " << o1 << endl;
    
    	/*---------------------- fills arrays with random numbers.------------------------
    	*	 void RNG:: fill( InputOutputArray mat, int distType, InputArray a,
    							InputArray b, bool saturateRange=false )函数原型
    	*	mat – 2D or N-dimensional matrix; currently matrices with more than 4 channels 
    		are not supported by the methods, use Mat::reshape() as a possible workaround
    		说明了输入矩阵的形式，目前尚不支持4通道以上的矩阵，如果超过了，需要调用reshape()函数
    		进行变更
    	*	distribution type, RNG::UNIFORM or RNG::NORMAL 分布的类型(均匀或高斯)
    	*	a – first distribution parameter; in case of the uniform distribution, this is an
    		inclusive lower boundary, in case of the normal distribution, this is a mean value
    		当为均匀分布时，a为下界(闭区间),当为高斯分布时，表示均值
    	*	b – second distribution parameter; in case of the uniform distribution, this is a 
    		non-inclusive upper boundary, in case of the normal distribution, this is a standard deviation 
    		(diagonal of the standard deviation matrix or the full standard deviation matrix)
    		当为均匀分布时，a为上界(开区间),当为高斯分布时，表示标准差
    	*	saturateRange – pre-saturation flag; for uniform distribution only; if true, the method will
    		first convert a and b to the acceptable value range (according to the mat datatype) and
    		then will generate uniformly distributed random numbers within the range [saturate(a),
    		saturate(b)) , if saturateRange=false, the method will generate uniformly distributed
    		random numbers in the original range [a, b) and then will saturate them, it means, for example, 
    		that theRNG().fill(mat_8u, RNG::UNIFORM, -DBL_MAX, DBL_MAX) will likely produce array mostly
    		filled with 0’s and 255’s, since the range (0, 255) is significantly smaller than [-DBL_MAX, DBL_MAX)
    		意思是：此变量只针对均匀分布有效。当为真的时候，会先把产生随机数的范围变换到数据类型的范围，
    		再产生随机数；如果为假，会先产生随机数，再进行截断到数据类型的有效区间。请看以下fillM1和
    		fillM2的例子并观察结果
    	------------------------------------------------------------------------------------*/
    	Mat_<int>fillM(3,3);
    	rng.fill(fillM,RNG::UNIFORM,1,1000);
    	cout << "filM = " << fillM << endl << endl;
    
    	Mat fillM1(3,3,CV_8U);
    	rng.fill(fillM1,RNG::UNIFORM,1,1000,TRUE);
    	cout << "filM1 = " << fillM1 << endl << endl;
    
    	//fillM1产生的数据都在[0,，255)内，且小于255；
    	//fillM2产生的数据虽然也在同样范围内，但是由于用了截断操作，所以很多数据都是255,
    	//因为CV_8U的有效范围就是0~255
    	//所以我认为最好的方式就是事先想好需要的数据类型和范围，再设置为FALSE(默认值)
    	Mat fillM2(3,3,CV_8U);
    	rng.fill(fillM2,RNG::UNIFORM,1,1000,FALSE);
    	cout << "filM2 = " << fillM2 << endl << endl;
    
    	/*------- uniformly-distributed random number or an array of random numbers----
    	*	randu(dst, low, high) 
    	*	dst – output array of random numbers; 
    	*	low – inclusive lower boundary of the generated random numbers;
    	*	high - exclusive upper boundary of the generated random numbers;
    	-----------------------------------------------------------------------------*/
    	Mat_<int>randuM(3,3);
    	randu(randuM,Scalar(0),Scalar(255));
    	cout << "randuM = " << randuM << endl << endl;
    
    	/*---------------normally distributed random numbers-------------------
    	*	randn(dst, mean, stddev)(也叫高斯分布)
    	*	dst – output array of random numbers; 
    		the array must be pre-allocated and have 1 to 4 channels;
    	*	mean(均值) – mean value (expectation) of the generated random numbers
    	*	stddev - standard deviation(标准差) of the generated random numbers; it can be either a vector
    		(in which case a diagonal standard deviation matrix is assumed) or a square matrix
    	-----------------------------------------------------------------------------*/
    	Mat_<int>randnM(3,3);
    	randn(randnM,0,1);
    	cout << "randnM = " << randnM << endl << endl;
    
    	/*-----------------Shuffles the array elements randomly(产生随机打乱的矩阵)---------------
    	*	randShuffle( InputOutputArray dst, double iterFactor=1., RNG* rng=0 )
    	*	dst -  input/output numerical 1D array;
    	*	iterFactor - scale factor that determines the number of random swap operations;
    	*	rng -  optional random number generator used for shuffling; if it is zero, 
    		theRNG()() is used instead;
    	*	The function randShuffle shuffles the specified 1D array by randomly choosing 
    		pairs of elements and swapping them. The number of such swap operations will be
    		dst.rows*dst.cols*iterFactor 
    	-----------------------------------------------------------------------------*/
    	Mat_<int>randShufM(4,1);
    	randShuffle(randShufM,1,0);
    	cout << "randShufM = " << randShufM << endl << endl;
    	//还不太会用...
    
    	/*------------------------下面介绍一下C版的随机数产生器的相关函数---------------*/
    
    	/*------- initializes a random number generator state(初始化随机数生成器状态)-----
    	*	 CvRNG cvRNG( int64 seed=-1) 函数原型
    	*	seed – 64-bit value used to initiate a random sequence
    		64-bit的值用来初始化随机序列；
    		函数 cvRNG 初始化随机数生成器并返回其状态。
    		指向这个状态的指针可以传递给函数 cvRandInt, cvRandReal 和 cvRandArr；
    		在通常的实现中使用一个 multiply-with-carry generator
    		C++版本中的RNG已经代替了CvRNG
    	-----------------------------------------------------------------------------*/
    	//CvRNG rng1 = cvRNG(-1);
    	CvRNG cvRNG;
    
    	/*------- fills an array with random numbers and updates the RNG state-------
    	*	 void cvRandArr( CvRNG* rng, CvArr* arr, int dist_type, 
    						CvScalar param1, CvScalar param2)函数原型
    	*	rng – CvRNG state initialized by RNG()被 cvRNG 初始化的 RNG 状态
    	*	arr – The destination array
    	*	dist_type – Distribution type
    		- CV_RAND_UNI uniform distribution
    		- CV_RAND_NORMAL normal or Gaussian distribution
    	*	param1 – The first parameter of the distribution. In the case of a uniform distribution it
    		is the inclusive lower boundary of the random numbers range. In the case of a normal
    		distribution it is the mean value of the random numbers
    		如果是均匀分布它是随机数范围的闭下边界；如果是正态分布它是随机数的平均值
    	*	param2 – The second parameter of the distribution. In the case of a uniform distribution
    		it is the exclusive upper boundary of the random numbers range. In the case of a normal
    		distribution it is the standard deviation of the random numbers
    		如果是均匀分布它是随机数范围的开上边界；如果是正态分布它是随机数的标准差
    	-----------------------------------------------------------------------------*/
    	CvMat* cvM = cvCreateMat(3,3,CV_16U);
    	cvRandArr(&cvRNG,cvM,CV_RAND_UNI,cvScalarAll(0),cvScalarAll(255));
    	cout << "cvM = " << cvM << endl << endl;
    	//这里输出有点奇怪，明明定义的是矩阵，却输出的一串数字，不理解？
    
    	/*------- returns a 32-bit unsigned integer and updates RNG-------
    	*	unsigned int cvRandInt( CvRNG* rng)函数原型 
    	*	rng – CvRNG state initialized by RNG()
    		函数 cvRandInt 返回均匀分布的随机 32-bit 无符号整型值并更新 RNG 状态；
    		它和 C 运行库里面的 rand() 函数十分相似，但是它产生的总是一个 32-bit 数而 rand()
    		返回一个 0 到 RAND_MAX（它是 2**16 或者 2**32, 依赖于操作平台）之间的数
    	-----------------------------------------------------------------------------*/
    	int cvInt = cvRandInt(&cvRNG);
    	cout << "cvInt = " << cvInt << endl;
    
    	/*------- returns a floating-point random number and updates RNG.-------
    	*	double cvRandReal( CvRNG* rng)函数原型 
    	*	rng – RNG state initialized by RNG()
    		函数 cvRandReal 返回均匀分布的随机浮点数，范围在 0~1 之间 (不包括1)
    	-----------------------------------------------------------------------------*/
    	double cvDouble = cvRandReal(&cvRNG);
    	cout << "cvDouble = " << cvDouble << endl;
    
    	system("pause");
    	return 0;
    }

以下是结果：各个输出的变量名相互对应  
![20141204090240940][]

同时也可以看到fillM1和fillM2之间的区别。

以下给出RNG类在OpenCV中源代码：

/*!
       Random Number Generator
       The class implements RNG using Multiply-with-Carry algorithm
    */
    class CV_EXPORTS RNG
    {
    public:
        enum { UNIFORM=0, NORMAL=1 };
    
    	
    RNG();//默认构造函数
    // inline RNG::RNG() { state = 0xffffffff; }
    
    RNG(uint64 state);//带参数的构造函数，接受一个64位无符号的值。
    //inline RNG::RNG(uint64 _state) { state = _state ? _state : 0xffffffff; }
    
    
    //! updates the state and returns the next 32-bit unsigned integer random number
        unsigned next();
    /*
    inline unsigned RNG::next()
    {
        state = (uint64)(unsigned)state*CV_RNG_COEFF + (unsigned)(state >> 32);
        return (unsigned)state;
    }
    #define CV_RNG_COEFF 4164903690U
    用两个很大的无符号数相乘，乘积结果要转换为64位无符号数，转换的时候两个乘数应该向高精度看起，所以应该也先转换为64位再相乘。把state右移32位得到一个数，把这两个数相加。函数返回一个32位的无符号数，其值为截断前面求得的和。
    */
    
    //以下几个函数是从类到uchar.schar,ushort,short,usinged的显示转换函数
    operator uchar();//返回一个8位无符号类型的随机数，把next返回的数截断
    //inline RNG::operator uchar() { return (uchar)next(); }
    
    operator schar();//返回一个8为有符号类型的随机数。???会产生负数吗，返回的也是截断的next返回值。莫非是截断后得到的最高位作为符号位，这样也可能是随机的。???
    //inline RNG::operator schar() { return (schar)next(); }
    
    operator ushort();//返回一个无符号16为整数
    //inline RNG::operator ushort() { return (ushort)next(); }
    
    operator short();//返回一个有符号16为整数
    // inline RNG::operator short() { return (short)next(); }
    
    
    operator unsigned();//返回一个无符号32为整数
    // inline RNG::operator unsigned() { return next(); }
    
    
    //! returns a random integer sampled uniformly from [0, N).
    unsigned operator ()(unsigned N);//重载括号操作符，带参数。在(0,N)之间返回一个整数，调用uniform成员函数
    //inline unsigned RNG::operator ()(unsigned N) {return (unsigned)uniform(0,N);}
    
    
    unsigned operator ()();//重载括号操作符，无参数。直接返回next结果。
    // inline unsigned RNG::operator ()() {return next();}
    
    
    //放在这个位置有点奇怪，为什么不和前边同类放一起呢？放回一个带符//号32为整数
    operator int();
    // inline RNG::operator int() { return (int)next(); }
    
    //返回一个float型(具体多少位看平台)数。
    operator float();
    // inline RNG::operator float() { return next()*2.3283064365386962890625e-10f; }
    
    //两个数按位或一下
    operator double();
    /*
    inline RNG::operator double()
    {
        unsigned t = next();
        return (((uint64)t << 32) | next())*5.4210108624275221700372640043497e-20;
    }*/
    
    
    //! returns uniformly distributed integer random number from [a,b) range
    int uniform(int a, int b);//[a,b)内随机产生一个int型值，均匀分布
    // inline int RNG::uniform(int a, int b) { return a == b ? a : (int)(next()%(b - a) + a); }
    
    
    //! returns uniformly distributed floating-point random number from [a,b) range
    float uniform(float a, float b); //[a,b)内随机产生一个float型值，均匀分布
    // inline float RNG::uniform(float a, float b) { return ((float)*this)*(b - a) + a; }
    
    
    //! returns uniformly distributed double-precision floating-point random number from [a,b) range
    double uniform(double a, double b); //[a,b)内随机产生一个double型值，均匀分布
    // inline double RNG::uniform(double a, double b) { return ((double)*this)*(b - a) + a; }
    
    void fill( InputOutputArray mat, int distType, InputArray a, InputArray b, bool saturateRange=false );//这个函数实现很长，暂时略过。
    
    //! returns Gaussian random variate with mean zero.
    double gaussian(double sigma);//返回均值为0的高斯随机变量，
    /*double RNG::gaussian(double sigma)
    {
        float temp;
        randn_0_1_32f( &temp, 1, &state );
        return temp*sigma;
    }*/
    	
    
    uint64 state;//种子，next中需要这样一个初始值
    };

以下是一个以RNG的例子，画随机直线和在图像中添加字符：

#include <iostream>
    #include "cv.h"
    #include "highgui.h"
    
    using namespace std;
    using namespace cv;
    
    const char wndName[] = "randDraw";
    const int randNumber = 100;
    
    static Scalar randomColor(RNG& rng)
    {
    	int rColor = (unsigned)rng;
    	//颜色是用RGB三通道表示,因此上面函数中颜色参数的类型都是Scalar类型
    	//将随机数的值取出分别作为RGB三个通道的颜色值
    	return Scalar(rColor & 0xFF,(rColor >> 8) & 0xFF,(rColor >> 16) & 0xFF);
    }
    
    int main(int argc,char** argv)
    {
    	 //抗锯齿，平滑线
    	//改为8就不是咯~
    	int lineType = CV_AA; 
    	int width = 1000;
    	int height = 700;
    	int x1 = - width/2;
    	int x2 = 3 * width/2;
    	int y1 = - height/2;
    	int y2 = 3 * height/2;
    	const int DELAY = 10;
    
    	//0xFFFFFFFF表示初始的随机值
    	//RNG rng(0xFFFFFFFF);
    	RNG rng;
    	Mat image = Mat::zeros(height,width,CV_8UC3);
    	imshow(wndName,image);
    	waitKey(DELAY);
    
    	for(int i = 0;i < randNumber;i++)
    	{
    		Point pt1;
    		Point pt2;
    		pt1.x = rng.uniform(x1,x2);
    		pt1.y = rng.uniform(y1,y2);
    		pt2.x = rng.uniform(x1,x2);
    		pt2.y = rng.uniform(y1,y2);
    		/*----------------------draws a line segment connecting two points-----------
    		*	void line( Mat& img, Point pt1, Point pt2, const Scalar& color,
    						int thickness=1, int lineType=8, int shift=0)函数原型
    		*	lineType – Type of the line:
    						– 8 (or omitted) - 8-connected line.
    						– 4 - 4-connected line.
    						– CV_AA - antialiased line.
    		-----------------------------------------------------------------------------*/
    		line(image,pt1,pt2,randomColor(rng),rng.uniform(1,10),lineType);
    	}
    	imshow(wndName,image);
    	waitKey(0);
    
    	for(int i = 0;i < randNumber;i++)
    	{
    		Point org;
    		org.x = rng.uniform(x1,x2);
    		org.y = rng.uniform(y1,y2);
    
    		/*-------------------------draws a text string--------------------------------
    		*	void putText(Mat& img, const string& text, Point org, int fontFace, 
    						double fontScale, Scalar color,int thickness=1, 
    							int lineType=8, bool bottomLeftOrigin=false )函数原型
    		*	img – image
    		*	text – Text string to be drawn
    		*	org – Bottom-left corner of the text string in the image.
    		*	font – CvFont structure initialized using InitFont() C版本的参数
    		*	fontFace – Font type. One of FONT_HERSHEY_SIMPLEX, FONT_HERSHEY_PLAIN,
    						FONT_HERSHEY_DUPLEX, FONT_HERSHEY_COMPLEX, FONT_HERSHEY_TRIPLEX,
    						FONT_HERSHEY_COMPLEX_SMALL, FONT_HERSHEY_SCRIPT_SIMPLEX, or
    						FONT_HERSHEY_SCRIPT_COMPLEX, where each of the font ID’s can be 
    						combined with FONT_HERSHEY_ITALIC to get the slanted letters
    		*	fontScale – Font scale factor that is multiplied by the font-specific base size
    		*	color – Text color
    		*	thickness – Thickness of the lines used to draw a text
    		*	lineType – Line type. See the line for details
    		*	bottomLeftOrigin – When true, the image data origin is at the bottom-left corner；
    			Otherwise, it is at the top-left corner.如果为真，图像原点在左下角，否则在左上角
    		-----------------------------------------------------------------------------*/
    		putText(image,"OpenCV",org,rng.uniform(0,8),rng.uniform(0,10)*0.5 + 0.1,
    			randomColor(rng),rng.uniform(1,10),lineType,FALSE);
    	}
    
    	imshow(wndName,image);
    	waitKey(0);
    	return 0;
    }

以下是测试结果：

![20141204180345268][]

![20141204180354893][]

最后，再列出一个OpenCV自带Demo，我稍微对函数进行了注释。主要是为了练习使用随机数生成器和如何使用OpenCV画图。

#include <iostream>
    #include "cv.h"
    #include "highgui.h"
    
    using namespace std;
    using namespace cv;
    
    static void help()
    {
    	cout << "This program demonstrates OpenCV drawing and text output functions" << endl 
    		<< "Usage:" << endl
    		<<"./drawing" << endl;
    }
    
    static Scalar randomColor(RNG& rng)
    {
    	int iColor = unsigned(rng);
    	//255 = 0xFF
    	return Scalar(iColor & 255,(iColor >> 8) & 255,(iColor >> 16) & 255);
    }
    
    int main(int argc,char** argv)
    {
    	help();
    	char wndName[] = "Drawing Demo";
    	const int randomNumber = 100;
    	const int DELAY = 10;
    	int lineType = CV_AA;
    	int height = 700;
    	int width = 1000;
    	int x1 = - width/2;
    	int x2 = 3 * width/2;
    	int y1 = - height/2;
    	int y2 = 3 * height/2;
    	RNG rng(0xFFFFFFFF);
    
    	Mat image = Mat::zeros(height,width,CV_8UC3);
    	imshow(wndName,image);
    	waitKey(DELAY);
    
    	//draw line
    	for(int i = 0;i < randomNumber;i++)
    	{
    		Point pt1,pt2;
    		pt1.x = rng.uniform(x1,x2);
    		pt1.y = rng.uniform(y1,y2);
    		pt2.x = rng.uniform(x1,x2);
    		pt2.y = rng.uniform(y1,y2);
    		line(image,pt1,pt2,randomColor(rng),rng.uniform(1,10),lineType);
    		imshow(wndName,image);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    
    	//draw rectangle
    	for(int i = 0;i < randomNumber;i++)
    	{
    		Point pt1,pt2;
    		pt1.x = rng.uniform(x1,x2);
    		pt1.y = rng.uniform(y1,y2);
    		pt2.x = rng.uniform(x1,x2);
    		pt2.y = rng.uniform(y1,y2);
    		int thickness = rng.uniform(-3,10);
    
    		/*----------------------draws a simple, thick, or filled up-right rectangle-----------
    		*	C++: void rectangle(Mat& img, Point pt1, Point pt2, const Scalar& color, 
    								int thickness=1, int lineType=8,int shift=0)
    		*	C++: void rectangle(Mat& img, Rect rec, const Scalar& color, int thickness=1, 
    								int lineType=8, int shift=0)
    		*	img – image
    		*	pt1 – Vertex of the rectangle
    		*	pt2 – Vertex of the rectangle opposite to pt1 
    		*	rec – Alternative specification of the drawn rectangle
    		*	color – Rectangle color or brightness (grayscale image)
    		*	thickness – Thickness of lines that make up the rectangle. Negative values,
    			like CV_FILLED, mean that the function has to draw a filled rectangle
    		*	lineType – Type of the line. See the line() description
    		*	shift – Number of fractional bits in the point coordinates
    		-----------------------------------------------------------------------------*/
    		rectangle(image,pt1,pt2,randomColor(rng),MAX(thickness,-1),lineType);
    		imshow(wndName,image);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    
    
    
    
    	//draw ellipse
    	for(int i = 0; i < randomNumber;i++)
    	{
    		Point center;
    		center.x = rng.uniform(x1,x2);
    		center.y = rng.uniform(y1,y2);
    		Size axes;
    		axes.width = rng.uniform(0,200);
    		axes.height = rng.uniform(0,200);
    		double angle = rng.uniform(0,180);
    
    		/*---------draws a simple or thick elliptic arc or fills an ellipse sector---------
    		*	C++: void ellipse(Mat& img, Point center, Size axes, double angle, 
    								double startAngle,double endAngle,const Scalar& color, 
    								int thickness=1, int lineType=8, int shift=0)
    		*	C++: void ellipse(Mat& img, const RotatedRect& box, const Scalar& color, 
    								int thickness=1, int lineType=8)
    		*	img – image 
    		*	center – Center of the ellipse 椭圆中心
    		*	axes – Half of the size of the ellipse main axes 椭圆长轴的一半
    		*	angle – Ellipse rotation angle in degrees 椭圆旋转的角度
    		*	startAngle – Starting angle of the elliptic arc in degrees 弧度开始的角度
    		*	endAngle – Ending angle of the elliptic arc in degrees 弧度结束的角度
    		*	box – Alternative ellipse representation via RotatedRect or CvBox2D
    			This means that the function draws an ellipse inscribed in the rotated rectangle
    		*	color – Ellipse color
    		*	thickness – Thickness of the ellipse arc outline, if positive. Otherwise, this indicates that a
    			filled ellipse sector is to be drawn
    		*	lineType – Type of the ellipse boundary. See the line() description
    		*	shift – Number of fractional bits in the coordinates of the center and values of axes
    		-----------------------------------------------------------------------------*/
    		ellipse(image,center,axes,angle,angle - 100,angle + 200,randomColor(rng),rng.uniform(1,8),lineType);
    		imshow(wndName,image);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    
    	//draw polylines
    	for(int i = 0;i < randomNumber;i++)
    	{
    		Point pt[2][3];
    		pt[0][0].x = rng.uniform(x1,x2);
    		pt[0][0].y = rng.uniform(y1,y2);
    		pt[0][1].x = rng.uniform(x1,x2);
    		pt[0][1].y = rng.uniform(y1,y2);
    		pt[0][2].x = rng.uniform(x1,x2);
    		pt[0][2].y = rng.uniform(y1,y2);
    		pt[1][0].x = rng.uniform(x1,x2);
    		pt[1][0].y = rng.uniform(y1,y2);
    		pt[1][1].x = rng.uniform(x1,x2);
    		pt[1][1].y = rng.uniform(y1,y2);
    		pt[1][2].x = rng.uniform(x1,x2);
    		pt[1][2].y = rng.uniform(y1,y2);
    		const Point* ppt[2] = {pt[0],pt[1]};
    		int npt[] = {3,3};
    
    		/*-------------------draws several polygonal curves----------------------------
    		*	C++: void polylines(Mat& img, const Point** pts, const int* npts, int ncontours, 
    									bool isClosed, const Scalar& color, int thickness=1,
    										int lineType=8, int shift=0 )
    		*	C++: void polylines(InputOutputArray img, InputArrayOfArrays pts, bool isClosed, 
    							const Scalar& color,int thickness=1, int lineType=8, int shift=0 )
    		*	img – image
    		*	pts – Array of polygonal curves 多边形曲线数组
    		*	npts – Array of polygon vertex counters 顶点数组
    		*	ncontours – Number of curves 曲线数量
    		*	isClosed – Flag indicating whether the drawn polylines are closed or not
    						If they are closed,the function draws a line from the last vertex 
    						of each curve to its first vertex 标志曲线是否闭合
    		*	color – Polyline color
    		*	thickness – Thickness of the polyline edges
    		*	lineType – Type of the line segments. See the line() description
    		*	shift – Number of fractional bits in the vertex coordinates 
    		-----------------------------------------------------------------------------*/
    		polylines(image,ppt,npt,2,TRUE,randomColor(rng),rng.uniform(1,10),lineType);
    		imshow(wndName,image);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    
    	//draw polygons with filled area
    	for(int i = 0;i < randomNumber;i++)
    	{
    		Point pt[2][3];
    		pt[0][0].x = rng.uniform(x1, x2);
    		pt[0][0].y = rng.uniform(y1, y2);
    		pt[0][1].x = rng.uniform(x1, x2);
    		pt[0][1].y = rng.uniform(y1, y2);
    		pt[0][2].x = rng.uniform(x1, x2);
    		pt[0][2].y = rng.uniform(y1, y2);
    		pt[1][0].x = rng.uniform(x1, x2);
    		pt[1][0].y = rng.uniform(y1, y2);
    		pt[1][1].x = rng.uniform(x1, x2);
    		pt[1][1].y = rng.uniform(y1, y2);
    		pt[1][2].x = rng.uniform(x1, x2);
    		pt[1][2].y = rng.uniform(y1, y2);
    		const Point* ppt[2] = {pt[0], pt[1]};
    		int npt[] = {3, 3};
    
    		/*--------------fills the area bounded by one or more polygons---------------
    		*	C++: void fillPoly( Mat& img, const Point** pts, const int* npts, int ncontours,
    						const Scalar& color, int lineType=8, int shift=0, Point offset=Point() )
    		*	img – image
    		*	pts – Array of polygons where each polygon is represented as an array of points
    		*	npts – Array of polygon vertex counters
    		*	ncontours – Number of contours that bind the filled region
    		*	color – Polygon color
    		*	lineType – Type of the polygon boundaries. See the line() description
    		*	shift – Number of fractional bits in the vertex coordinates
    		*	offset – Optional offset of all points of the contours
    		-----------------------------------------------------------------------------*/
    		fillPoly(image, ppt, npt, 2, randomColor(rng), lineType);
    		imshow(wndName, image);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    
    	//draw circle
    	for(int i = 0;i < randomNumber;i++)
    	{
    		Point center;
    		center.x = rng.uniform(x1,x2);
    		center.y = rng.uniform(y1,y2);
    
    		/*-----------------------------draw a circle----------------------------------
    		*	C++: void circle(Mat& img, Point center, int radius, const Scalar& color,
    								int thickness=1, int lineType=8,int shift=0)
    		*	img – Image where the circle is drawn
    		*	center – Center of the circle
    		*	radius – Radius of the circle
    		*	color – Circle color
    		*	thickness – Thickness of the circle outline, if positive.
    						Negative thickness means that a
    		*	filled circle is to be drawn
    		*	lineType – Type of the circle boundary. See the line() description
    		*	shift – Number of fractional bits in the coordinates of the center and 
    			in the radius value
    		-----------------------------------------------------------------------------*/
    		circle(image,center,rng.uniform(0,300),randomColor(rng),rng.uniform(-1,9),lineType);
    		imshow(wndName,image);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    
    	//put text on the image
    	for(int i = 0;i < randomNumber;i++)
    	{
    		Point org;
    		org.x = rng.uniform(x1,x2);
    		org.y = rng.uniform(y1,y2);
    		putText(image,"Testing text rendering",org,rng.uniform(0,8)/*font type*/,
    				rng.uniform(0,100)*0.05 + 0.1/*font scale*/,
    					randomColor(rng),rng.uniform(1,10)/*thickness*/,lineType);
    		imshow(wndName,image);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    	
    	/*------------------calculates the width and height of a text string--------------
    	*	C++: Size getTextSize( const string& text, int fontFace, double fontScale,
    								int thickness, int* baseLine)
    	*	text – Input text string
    	*	fontFace – Font to use. See the putText() for details
    	*	fontScale – Font scale. See the putText() for details
    	*	thickness – Thickness of lines used to render the text
    	*	baseLine – Output parameter - y-coordinate of the baseline relative 
    					to the bottom-most text	point.
    	--------------------------------------------------------------------------------------*/
    	//string text = " OpenCV Forever!" ;
    	//int fontFace = FONT_HERSHEY_COMPLEX;
    	//double fontScale = 2;
    	//int thickness = 3;
    	//int baseline=0;
    	//baseline += thickness;
    	//Size textSize = getTextSize(text, fontFace,
    	//						fontScale, thickness, &baseline);
    
    	Size textSize = getTextSize("OpenCV Forever!",FONT_HERSHEY_COMPLEX,3,5,0);
    	Point org((width - textSize.width)/2,(height - textSize.height)/2);
    
    	Mat image2;
    	for(int i = 0;i < 255;i += 2)
    	{
    		image2 = image - Scalar::all(i);
    		putText(image2,"OpenCV Forever!",org,FONT_HERSHEY_COMPLEX,
    			3,Scalar(i,i,255),5,lineType);
    
    		imshow(wndName,image2);
    		if(waitKey(DELAY) >= 0)
    			return 0;
    	}
    
    	waitKey();
    	return 0;
    }

测试结果很有意思。顿时让我对OpenCV又爱上了几分。。。

![20141204180846781][]

![20141204180912713][]

![20141204180935551][]

![20141204180942665][]

[20141204090240940]: /images/20220806/4c171cd952704b318a03201ea14ac8ec.png
[20141204180345268]: /images/20220806/d1ea7814b64b448eab8f8fb4df88b01a.png
[20141204180354893]: /images/20220806/a3bf33a3d21345c7812507b0f91eb2dc.png
[20141204180846781]: /images/20220806/589c3c7ab3004a5e954e6009aa7c8d88.png
[20141204180912713]: /images/20220806/c0cad224446c49a28f423ad76e028e6d.png
[20141204180935551]: /images/20220806/4f56d45d98dc46f09e9b855de6fd8041.png
[20141204180942665]: /images/20220806/f60eeb1079944e43a3b15e126ba3ee2c.png