亮度和对比度处理

每个像素点   g(i,j)  = α⋅f(i,j) + β：

Mat::convertTo()

double alpha = 2;
	int beta = 50;
	Mat src = imread("img/7.jpg");
	Mat dst = Mat::zeros(src.size(), src.type());
	Mat dst2 = Mat::zeros(src.size(), src.type());

	for (int x = 0; x < src.rows; x++)
	{
		for (int y = 0; y < src.cols; y++)
		{
			//bgr三通道
			dst.at(x, y)[0] = saturate_cast(alpha*src.at(x, y)[0] + beta);
			dst.at(x, y)[1] = saturate_cast(alpha*src.at(x, y)[1] + beta);
			dst.at(x, y)[2] = saturate_cast(alpha*src.at(x, y)[2] + beta);
		}
	}
	src.convertTo(dst2, -1, alpha, beta);
	imshow("Normal", src);
	imshow("End",dst);
	imshow("End2", dst2);