OpenCV之基本绘图
2014-04-24 16:39
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相关函数介绍
Point
该数据结构表示了由其图像坐标 和 指定的2D点。可定义为:Point pt;
pt.x = 10;
pt.y = 8;
或者
Point pt = Point(10, 8);
Scalar
表示了具有4个元素的数组。次类型在OpenCV中被大量用于传递像素值。本节中,我们将进一步用它来表示RGB颜色值(三个参数)。如果用不到第四个参数,则无需定义。
我们来看个例子,如果给出以下颜色参数表达式:
Scalar( a, b, c )
那么定义的RGB颜色值为:Red = c, Green = b and Blue= a
Rectangle
C++: void rectangle(Mat& img,Point pt1, Pointpt2, const Scalar&color, intthickness=1,intlineType=8, intshift=0)C++: void rectangle(Mat& img,Rect rec, const Scalar&color, intthickness=1, intlineType=8,intshift=0 )
Parameters: | img – 画矩形的对象 pt1 – 矩形的一个顶点,左上角的. pt2 – 另一个顶点,右下角的. rec – 确定矩形的另一种方式,给左上角坐标和长宽 color – 指定矩形的颜色或亮度(灰度图像),scalar(255,0,255)既可指定. thickness – 矩形边框的粗细. 负值(like CV_FILLED)表示要画一个填充的矩形 lineType – 边框线型. ( 8 (or 0) - 8-connected line(8邻接)连接 线。 4 - 4-connected line(4邻接)连接线。 CV_AA - antialiased 线条。) shift –坐标点的小数点位数 |
Line
C++: void line(Mat& img, Point pt1,Point pt2, const Scalar& color, int thickness=1, int lineType=8,int shift=0)Parameters: | img – 图像. pt1 – 线条起点. pt2 – 线条终点. color – 线条颜色. thickness – 线条宽度. lineType – 线型 Type of the line: 8 (or omitted) - 8-connected line. 4 - 4-connected line. CV_AA - antialiased line. shift – 坐标点小数点位数. |
C++: void circle(Mat&img, Point center, intradius, const Scalar&color,intthickness=1, intlineType=8, intshift=0)
Parameters: | img – 要画圆的那个矩形. center – 圆心坐标. radius – 半径. color – 圆边框颜色,scalar类型的 thickness – 正值表示圆边框宽度. 负值表示画一个填充圆形 lineType – 圆边框线型 shift – 圆心坐标和半径的小数点位数 |
Ellipse
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, constRotatedRect& box, const Scalar& color, int thickness=1, int lineType=8)
Parameters: | img – 椭圆所在图像. center – 椭圆中心. axes – 椭圆主轴一半的长度 angle – 椭圆旋转角度 startAngle – 椭圆弧起始角度 endAngle –椭圆弧终止角度 box – 指定椭圆中心和旋转角度的信息,通过 RotatedRect 或 CvBox2D. 这表示椭圆画在旋转矩形上(矩形是不可见的,只是指定了一个框而已) color – 椭圆边框颜色. thickness – 正值代表椭圆边框宽度,负值代表填充的椭圆 lineType – 线型 shift – 椭圆中心坐标和坐标轴的小数点位数 |
PolyLine
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 )
Parameters: | img – 折线所在图像. pts – 折线中拐点坐标指针. npts – 折线拐点个数指针. ncontours – 折线线段数量. isClosed – 折线是否闭合. color – 折线颜色. thickness – 折线宽度. lineType – 线型. shift – 顶点坐标小数点位数. |
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PutText
C++: void putText(Mat& img, const string& text, Point org, int fontFace, double fontScale, Scalar color, int thickness=1, int lineType=8, bool bottomLeftOrigin=false )Parameters: | img – 显示文字所在图像. text – 待显示的文字. org – 文字在图像中的左下角 坐标. font – 字体结构体. fontFace – 字体类型, 可选择字体:FONT_HERSHEY_SIMPLEX, FONT_HERSHEY_PLAIN, FONT_HERSHEY_DUPLEX,FONT_HERSHEY_COMPLEX, FONT_HERSHEY_TRIPLEX, FONT_HERSHEY_COMPLEX_SMALL, FONT_HERSHEY_SCRIPT_SIMPLEX, orFONT_HERSHEY_SCRIPT_COMPLEX,以上所有类型都可以配合 FONT_HERSHEY_ITALIC使用,产生斜体效果。 fontScale – 字体大小,该值和字体内置大小相乘得到字体大小 color – 文本颜色 thickness – 写字的线的粗细,类似于0.38的笔尖和0.5的笔尖 lineType – 线性. bottomLeftOrigin – true, 图像数据原点在左下角. Otherwise, 图像数据原点在左上角. |
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示例代码
/** * @file Drawing_1.cpp * @brief Simple sample code */ #include <opencv2/core/core.hpp> #include <opencv2/highgui/highgui.hpp> #define w 400 using namespace cv; /// Function headers void MyEllipse( Mat img, double angle ); void MyFilledCircle( Mat img, Point center ); void MyPolygon( Mat img ); void MyLine( Mat img, Point start, Point end ); /** * @function main * @brief Main function */ int main( void ){ /// Windows names char atom_window[] = "Drawing 1: Atom"; char rook_window[] = "Drawing 2: Rook"; /// Create black empty images Mat atom_image = Mat::zeros( w, w, CV_8UC3 ); Mat rook_image = Mat::zeros( w, w, CV_8UC3 ); /// 1. Draw a simple atom: /// ----------------------- /// 1.a. Creating ellipses MyEllipse( atom_image, 90 ); MyEllipse( atom_image, 0 ); MyEllipse( atom_image, 45 ); MyEllipse( atom_image, -45 ); /// 1.b. Creating circles MyFilledCircle( atom_image, Point( w/2, w/2) ); /// 2. Draw a rook /// ------------------ /// 2.a. Create a convex polygon MyPolygon( rook_image ); /// 2.b. Creating rectangles rectangle( rook_image, Point( 0, 7*w/8 ), Point( w, w), Scalar( 0, 255, 255 ), -1, 8 ); RotatedRect rRect = RotatedRect(Point2f(100,100), Size2f(100,50), 30); ellipse(rook_image, rRect, Scalar(255,255,0)); /// 2.c. Create a few lines MyLine( rook_image, Point( 0, 15*w/16 ), Point( w, 15*w/16 ) ); MyLine( rook_image, Point( w/4, 7*w/8 ), Point( w/4, w ) ); MyLine( rook_image, Point( w/2, 7*w/8 ), Point( w/2, w ) ); MyLine( rook_image, Point( 3*w/4, 7*w/8 ), Point( 3*w/4, w ) ); /// 3. Display your stuff! imshow( atom_window, atom_image ); moveWindow( atom_window, 0, 200 ); imshow( rook_window, rook_image ); moveWindow( rook_window, w, 200 ); waitKey( 0 ); return(0); } /// Function Declaration /** * @function MyEllipse * @brief Draw a fixed-size ellipse with different angles */ void MyEllipse( Mat img, double angle ) { int thickness = 2; int lineType = 8; ellipse( img, Point( w/2, w/2 ), Size( w/4, w/16 ), angle, 0, 360, Scalar( 255, 0, 0 ), thickness, lineType ); } /** * @function MyFilledCircle * @brief Draw a fixed-size filled circle */ void MyFilledCircle( Mat img, Point center ) { int thickness = -1; int lineType = 8; circle( img, center, w/32, Scalar( 0, 0, 255 ), thickness, lineType ); } /** * @function MyPolygon * @function Draw a simple concave polygon (rook) */ void MyPolygon( Mat img ) { int lineType = 8; /** Create some points */ Point rook_points[1][20]; rook_points[0][0] = Point( w/4, 7*w/8 ); rook_points[0][1] = Point( 3*w/4, 7*w/8 ); rook_points[0][2] = Point( 3*w/4, 13*w/16 ); rook_points[0][3] = Point( 11*w/16, 13*w/16 ); rook_points[0][4] = Point( 19*w/32, 3*w/8 ); rook_points[0][5] = Point( 3*w/4, 3*w/8 ); rook_points[0][6] = Point( 3*w/4, w/8 ); rook_points[0][7] = Point( 26*w/40, w/8 ); rook_points[0][8] = Point( 26*w/40, w/4 ); rook_points[0][9] = Point( 22*w/40, w/4 ); rook_points[0][10] = Point( 22*w/40, w/8 ); rook_points[0][11] = Point( 18*w/40, w/8 ); rook_points[0][12] = Point( 18*w/40, w/4 ); rook_points[0][13] = Point( 14*w/40, w/4 ); rook_points[0][14] = Point( 14*w/40, w/8 ); rook_points[0][15] = Point( w/4, w/8 ); rook_points[0][16] = Point( w/4, 3*w/8 ); rook_points[0][17] = Point( 13*w/32, 3*w/8 ); rook_points[0][18] = Point( 5*w/16, 13*w/16 ); rook_points[0][19] = Point( w/4, 13*w/16 ); const Point* ppt[1] = { rook_points[0] }; int npt[] = { 20 }; fillPoly( img, ppt, npt, 1, Scalar( 255, 255, 255 ), lineType ); } /** * @function MyLine * @brief Draw a simple line */ void MyLine( Mat img, Point start, Point end ) { int thickness = 2; int lineType = 8; line( img, start, end, Scalar( 0, 0, 0 ), thickness, lineType ); }
实验结果
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