Opencv入門——圖像的亮度與對比度的調整

原理公式：

?(?, ?) = ??(?, ?) + ? （? > 0，?是增益變量）

調整圖像的亮度和對比度相當于對圖像每個像素點的操作

#include<iostream>
#include<opencv.hpp>

using namespace cv;
using namespace std;

int main(int argc, char **argv)
{
	Mat img, dst, ts;
	img = imread("D:\\OpenCV\\images\\9.jpg");
	if (img.empty())
	{
		cout << "image loading failed..." << endl;
		return -1;
	}
	
	namedWindow("input", WINDOW_AUTOSIZE);
	imshow("input", img);

	//單通道圖像測試，去掉注釋就可以
	//cvtColor(img, img, COLOR_BGR2GRAY);
	//imshow("img_gray", img);

	int height = img.rows;
	int weight = img.cols;
	int nc = img.channels();
	float alpha = 1.8;
	float beta = 10;
	float b, g, r, v;
	img.convertTo(ts, CV_32F);
	
	dst = Mat::zeros(img.size(), img.type());
	for (int row = 0; row < height; row++)
	{
		for (int col = 0; col < weight; col++)
		{
			if (nc == 1)
			{
				v = img.at<uchar>(row, col);
				dst.at<uchar>(row, col) = saturate_cast<uchar>(v*alpha + beta);
			}
			else
				if (nc == 3) {
					b = ts.at<Vec3f>(row, col)[0];
					g = ts.at<Vec3f>(row, col)[1];
					r = ts.at<Vec3f>(row, col)[2];

					dst.at<Vec3b>(row, col)[0] = saturate_cast<uchar>(b*alpha + beta);
					dst.at<Vec3b>(row, col)[1] = saturate_cast<uchar>(g*alpha + beta);
					dst.at<Vec3b>(row, col)[2] = saturate_cast<uchar>(r*alpha + beta);
				}
		}
	}
	imshow("brightness_img", dst);
	imwrite("D:\\OpenCV\\images\\btns_img.jpg", dst);

	waitKey(0);
	return 0;
}

           

最後，放幾張效果圖

單通道

三通道