OpenCV入门：(七：OpenCV取随机数以及显示文字)
1.随机颜色
OpenCV中自带了取随机数的方法，使用步骤：
RNG rng( 0xFFFFFFFF ); 随机数 = rng.uniform( 下限,上限 );
2.显示文字
void putText(Mat& img, const string& text, Point org, int fontFace, double fontScale, Scalar color, int thickness=1, int lineType=8, bool bottomLeftOrigin=false ) 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(). 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_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.
使用方法：
putText( image, "Testing text rendering", org, rng.uniform(0,8), rng.uniform(0,100)*0.05+0.1, randomColor(rng), rng.uniform(1, 10), lineType);
