005-OpenCV4

二、获取图像均值与方差

mean（输入）获取图像均值，类型为Scalar,三通道与单通道均可获取

meanStdDev(输入，均值，方差)获取图像均值与方差，三通道与单通道均可获取

代码如下：

	Scalar s=mean(src);//获取图像均值
	cout.setf(ios::fixed);
	std::cout << "mean_b:" << setprecision(2) << s[0] << std::endl;
	std::cout << "mean_g:" << setprecision(2) << s[1] << std::endl;
	std::cout << "mean_r:" << setprecision(2) << s[2] << std::endl;

	Mat mm ,mstd;

	meanStdDev(src, mm, mstd);//获取图像方差
	int rows = mstd.rows;
	std::cout << "rows:" << rows << std::endl;
	std::cout << "stddev_b:" << setprecision(2) <(0,0) << std::endl;
	std::cout << "stddev_g:" << setprecision(2) << mstd.at(1, 0) << std::endl;
	std::cout << "stddev_r:" << setprecision(2) << mstd.at(2, 0) << std::endl;

像素值统计信息：

//像素值统计信息
	vectorhist(256);
	for (int i = 0; i < 256; i++) {
		hist[i] = 0;
	}
	for (int row = 0; row < h; row++) {
		for (int col = 0; col < w; col++) {
			int pv = src.at(row, col);
			hist[pv]++;

		}
	}