RNG rng(seed); int icolor = (unsigned)rng; return Scalar(icolor & 255, (icolor >> 8) & 255, (icolor >> 16) & 255);

一种推荐的做法是，使用opencv自己的时间函数作为随机数的种子。

cv::line(dst, cv::Point(x, y), 
			cv::Point(x2, y2), 
			randomColor(cv::getTickCount()), 2);