调整亮度和对比度就是对每个相元进行操作，乘于一定的参数

根据方程：

OpenCv-006-调整亮度和对比度_数据


其中α就是要提高的对比度，β为亮度

循环遍历每个操作完成对比度和亮度的提高：

for (int row = 0; row < height; row++) {
    for (int col = 0; col < width; col++) {
      if (src.channels() == 3) {
        float b = src.at<Vec3b>(row, col)[0]; //3f 为b g r
        float g = src.at<Vec3b>(row, col)[1]; //3f 为b g r
        float r = src.at<Vec3b>(row, col)[2]; //3f 为b g r
        dst.at<Vec3b>(row, col)[0] = saturate_cast<uchar>(alpha*b + bete);  //saturate_cast<uchar> 确保数据在范围内
        dst.at<Vec3b>(row, col)[1] = saturate_cast<uchar>(alpha*g + bete);
        dst.at<Vec3b>(row, col)[2] = saturate_cast<uchar>(alpha*r + bete);
      }
    }
  }

​​saturate_cast<uchar>​​ 确保数据在范围内

案例演示：

#include <opencv2\opencv.hpp>
#include <iostream>
using namespace std;
using namespace cv;
int main()
{
  Mat src, dst;
  src = imread("F:/opencv/InputImg/h3.jpg");
  if (src.empty()) cout << "图像打开失败！";
  char input_win[] = "input img";
  namedWindow(input_win, CV_WINDOW_AUTOSIZE);
  imshow(input_win, src);

  int height = src.rows;
  int width = src.cols;
  float alpha = 1.2; //对比度
  float bete = 100; //亮度
  dst = Mat::zeros(src.size(), src.type());  //创建空图像
  for (int row = 0; row < height; row++) {
    for (int col = 0; col < width; col++) {
      if (src.channels() == 3) {
        float b = src.at<Vec3b>(row, col)[0]; //3f 为b g r
        float g = src.at<Vec3b>(row, col)[1]; //3f 为b g r
        float r = src.at<Vec3b>(row, col)[2]; //3f 为b g r
        dst.at<Vec3b>(row, col)[0] = saturate_cast<uchar>(alpha*b + bete);  //saturate_cast<uchar> 确保数据在范围内
        dst.at<Vec3b>(row, col)[1] = saturate_cast<uchar>(alpha*g + bete);
        dst.at<Vec3b>(row, col)[2] = saturate_cast<uchar>(alpha*r + bete);
      }
    }
  }
  namedWindow(input_win, CV_WINDOW_AUTOSIZE);
  imshow("change img", dst);
  waitKey(0);
}

OpenCv-006-调整亮度和对比度_#include_02