Opencv C ++ 线性对比度展宽实现

线性对比度展宽

斜率计算 ：（y2-y1）/ (x2-x1)
即为 α 、β 、γ
a,b 为灰度图的区域
ga,gb 为原图展开区域

Mat f, out, out2;
	Mat g = imread("5.png");  //读取图片 转灰度图
	imshow("原图", g);
	cvtColor(g, f, COLOR_BGR2GRAY);
	float a = 40.0, b = 180.0;
	float ga = 150.0, gb = 200.0;
	float aref = (ga - 0.0) / (a - 0.0), bt = (gb - ga) / (b - a), gam = (255.0 - gb) / (255.0 - b);
	cout << aref << endl;
	cout << bt << endl;
	cout << gam << endl;
	for (int i = 0; i < f.rows; i++)
	{
     
		for (int j = 0; j < f.cols; j++)
		{
     
			int ff = f.at<uchar>(i, j);
			if (ff < a && ff >= 0) {
     
				g.at<Vec3b>(i, j)[0] = aref * g.at<Vec3b>(i, j)[0];
				g.at<Vec3b>(i, j)[1] = aref * g.at<Vec3b>(i, j)[1];
				g.at<Vec3b>(i, j)[2] = aref * g.at<Vec3b>(i, j)[2];
			}
			else if (ff < b&&ff >= a) {
     
				g.at<Vec3b>(i, j)[0] = bt * (g.at<Vec3b>(i, j)[0] - a) + ga;
				g.at<Vec3b>(i, j)[1] = bt * (g.at<Vec3b>(i, j)[1] - a) + ga;
				g.at<Vec3b>(i, j)[2] = bt * (g.at<Vec3b>(i, j)[2] - a) + ga;
			}
			else if (ff >= b && ff < 255) {
     
				g.at<Vec3b>(i, j)[0] = ga * (g.at<Vec3b>(i, j)[0] - b) + gb;
				g.at<Vec3b>(i, j)[1] = ga * (g.at<Vec3b>(i, j)[1] - b) + gb;
				g.at<Vec3b>(i, j)[2] = ga * (g.at<Vec3b>(i, j)[2] - b) + gb;
			}
		}
	}

	imshow("增强后的图", g);
	waitKey(0);

增强前：

增强后：

是不是很神奇？