opencv提供的一些繪圖函式，來簡單的繪製一個簡易的圖形，包括線段、矩形、橢圓、多邊形等。

1.線段

opencv提供了line()函式來對直線的繪製。其原型如下：

CV_EXPORTS_W void line(CV_IN_OUT Mat& img, Point pt1, Point pt2, const Scalar& color,
int thickness=1, int lineType=8, int shift=0);

2.橢圓

opencv提供了ellipse()函式來繪製橢圓。其原型如下：

CV_EXPORTS_W void ellipse(CV_IN_OUT Mat& img, Point center, Size axes,double angle, double startAngle, double endAngle,
const Scalar& color, int thickness=1,int lineType=8, int shift=0);

3.矩形

opencv提供了rectangle()函式來繪製矩形。其原型如下：

CV_EXPORTS_W void rectangle(CV_IN_OUT Mat& img, Point pt1, Point pt2,
const Scalar& color, int thickness=1,int lineType=8, int shift=0);

4.圓

opencv提供了circle()函式來繪製圓。其原型如下：

CV_EXPORTS_W void circle(CV_IN_OUT Mat& img, Point center, int radius,
const Scalar& color, int thickness=1,int lineType=8, int shift=0);
 

5.填充多邊形

opencv為我們提供了fillPoly()函式來繪製填充多邊形。其原型如下：

CV_EXPORTS void fillPoly(Mat& img, const Point** pts,const int* npts, int ncontours,
const Scalar& color, int lineType=8, int shift=0,Point offset=Point() );

6.顯示文字

void putText(Mat& img, const string& text, Point org, int fontFace, double fontScale, Scalar color, 
int thickness=1, int lineType=8, bool bottomLeftOrigin=false )

利用上述函式，例項1：

#include<opencv2/core/core.hpp>  
#include<opencv2/highgui/highgui.hpp>  
  
using namespace cv;    
#define WINDOW_SIZE   400  
  
void DrawEllipse(Mat img,double angle);  
void DrawFilledCircle(Mat img,Point center);  
void DrawPolygon(Mat img);  
void DrawLine(Mat img,Point start,Point end);  
  
int main(int argc,char** argv)  
{  
    //建立空白的影象  
    Mat atomImg=Mat::zeros(WINDOW_SIZE,WINDOW_SIZE,CV_8UC3);  
    Mat rookImg=Mat::zeros(WINDOW_SIZE,WINDOW_SIZE,CV_8UC3);  
  
    //------------------------------------繪製原子的示例圖------------------------------------  
    //繪製出橢圓  
    DrawEllipse(atomImg,90);  
    DrawEllipse(atomImg,0);  
    DrawEllipse(atomImg,45);  
    DrawEllipse(atomImg,-45);  
	namedWindow("ImageEll",CV_WINDOW_NORMAL);  
    imshow("ImageEll",atomImg);  
    //再繪製出圓心  
    DrawFilledCircle(atomImg,Point(WINDOW_SIZE/2,WINDOW_SIZE/2));  
	namedWindow("ImageEll+Circle",CV_WINDOW_NORMAL); 
    imshow("ImageEll+Circle",atomImg); 
  
    //繪製會多邊形  
    DrawPolygon(rookImg);  
	//顯示多邊形
	namedWindow("polygon",CV_WINDOW_NORMAL);  
    imshow("polygon",rookImg);  
    //繪製矩形  
    rectangle(rookImg,Point(0,7*WINDOW_SIZE/8),      //兩個對角定點  
        Point(WINDOW_SIZE,WINDOW_SIZE),  
        Scalar(0,255,255),             //矩陣顏色影象  
        -1,                            //由於線粗為-1,,此舉真將被填充  
        8);  
	//顯示多邊形+矩形
	namedWindow("ImageRook",CV_WINDOW_NORMAL);  
    imshow("ImageRook",rookImg);  
    waitKey(0);  
    return 0;  
}  
  
/*************************************************************************************************** 
函式功能: 
       繪製一條直線 
函式引數: 
       1---畫一條從點start到點end的直線段 
       2---此線段將被滑到影象img上 
       3---線的顏色有Scalar(0,0,0)來定義 
       4---線的粗細由thickness設定 
       5---線的型別由lineType決定,此處為8連通 
***************************************************************************************************/  
void DrawLine(Mat img,Point start,Point end)  
{  
    int thickness=2;  
    int lineType=8;  
    line(img,start,end,Scalar(0,0,0),thickness,lineType);  
}  
/*************************************************************************************************** 
函式功能: 
       繪製一個橢圓 
函式引數: 
       1---橢圓將被畫到img影象上 
       2---橢圓的中心點為Point(WINDOW_SIZE/2.0,WINDOW_SIZE/2.0),並且大小位於矩陣 
           Size(WINDOW_SIZE/4.0,WINDOW_SIZE/16.0), 
       3---橢圓的旋轉角度為angle 
       4---橢圓拓展的弧度為0到360度 
       5--圖形顏色為Scalar(255,0,255) 
       6--橢圓的粗度為thickness 
       7--線條的型別為lineType---8連通域 
***************************************************************************************************/  
void DrawEllipse(Mat img,double angle)  
{  
    int thickness=2;  
    int lineType=8;  
    ellipse(img,  
        Point(WINDOW_SIZE/2.0,WINDOW_SIZE/2.0),  
        Size(WINDOW_SIZE/4.0,WINDOW_SIZE/16.0),  
        angle,  
        0,  
        360,  
        Scalar(255,0,255),  
        thickness,  
        lineType);  
}  
/*************************************************************************************************** 
函式功能: 
       繪製一個圓 
函式引數: 
       1---圓將被畫到img影象上 
       2---圓心由center定義 
       3---圓的半徑為:WINDOW_SIZE/32.0 
       4---圓的顏色Scalar(0,0,255) 
       5---線的粗細為thickness=-1,因此,圓將被填充 
***************************************************************************************************/  
void DrawFilledCircle(Mat img,Point center)  
{  
    int thickness=-1;  
    int lineType=8;  
    circle(img,  
        center,  
        WINDOW_SIZE/32.0,  
        Scalar(0,0,255),  
        thickness,  
        lineType);  
}  
/*************************************************************************************************** 
函式功能: 
       繪製多邊形 
函式引數: 
       1---多邊形將被畫到img上 
       2---多邊形的頂點集為ppt 
       3---要繪製的多邊形定點數目為npt 
       4---要繪製的多邊形數量為1 
       5---多邊形的顏色定義為Scalar(255,255,255),即BGR的值為白色 
***************************************************************************************************/  
void DrawPolygon(Mat img)  
{  
    int lineType=0;  
  
    //建立一些點  
      Point rookPoints[1][20];  
      rookPoints[0][0]  =Point(WINDOW_SIZE/4,7*WINDOW_SIZE/8);  
      rookPoints[0][1]  =Point(3*WINDOW_SIZE/4,7*WINDOW_SIZE/8);  
      rookPoints[0][2]  = Point(3*WINDOW_SIZE/4,13*WINDOW_SIZE/16 );  
      rookPoints[0][3]  = Point(11*WINDOW_SIZE/16,13*WINDOW_SIZE/16 );  
      rookPoints[0][4]  = Point(19*WINDOW_SIZE/32,3*WINDOW_SIZE/8 );  
      rookPoints[0][5]  = Point(3*WINDOW_SIZE/4,3*WINDOW_SIZE/8 );  
      rookPoints[0][6]  = Point(3*WINDOW_SIZE/4,WINDOW_SIZE/8 );  
      rookPoints[0][7]  = Point(26*WINDOW_SIZE/40,WINDOW_SIZE/8 );  
      rookPoints[0][8]  = Point(26*WINDOW_SIZE/40,WINDOW_SIZE/4 );  
      rookPoints[0][9]  = Point(22*WINDOW_SIZE/40,WINDOW_SIZE/4 );  
      rookPoints[0][10] = Point(22*WINDOW_SIZE/40,WINDOW_SIZE/8 );  
      rookPoints[0][11] = Point(18*WINDOW_SIZE/40,WINDOW_SIZE/8 );  
      rookPoints[0][12] = Point(18*WINDOW_SIZE/40,WINDOW_SIZE/4 );  
      rookPoints[0][13] = Point(14*WINDOW_SIZE/40,WINDOW_SIZE/4 );  
      rookPoints[0][14] = Point(14*WINDOW_SIZE/40,WINDOW_SIZE/8 );  
      rookPoints[0][15] = Point(WINDOW_SIZE/4,WINDOW_SIZE/8 );  
      rookPoints[0][16] = Point(WINDOW_SIZE/4,3*WINDOW_SIZE/8 );  
      rookPoints[0][17] = Point(13*WINDOW_SIZE/32,3*WINDOW_SIZE/8 );  
      rookPoints[0][18] = Point(5*WINDOW_SIZE/16,13*WINDOW_SIZE/16 );  
      rookPoints[0][19] = Point(WINDOW_SIZE/4,13*WINDOW_SIZE/16 );  
  
      const Point* ppt[1]={rookPoints[0]};  
      int npt[]={20};  
      fillPoly(img,  
          ppt,  
          npt,  
          1,  
          Scalar(255,255,255),  
          lineType);  
}  

附：常見顏色RGB值對照表

參考：

http://blog.csdn.NET/ubunfans/article/details/24421981

http://lib.csdn.Net/article/opencv/29052

http://blog.csdn.net/gdfsg/article/details/50867809