OPENCV 在线修正图像参数

#include <iostream>
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"

// we're NOT "using namespace std;" here, to avoid collisions between the beta variable and std::beta in c++17
using std::cout;
using std::endl;
using namespace cv;

namespace
{
   /** Global Variables */
   int alpha = 100;
   int beta = 100;
   int gamma_cor = 100;
   Mat img_original, img_corrected, img_gamma_corrected;

   void basicLinearTransform(const Mat &img, const double alpha_, const int beta_)
   {
       Mat res;
       img.convertTo(res, -1, alpha_, beta_);

       hconcat(img, res, img_corrected);
       imshow("Brightness and contrast adjustments", img_corrected);
   }

   void gammaCorrection(const Mat &img, const double gamma_)
   {
       CV_Assert(gamma_ >= 0);
       //! [changing-contrast-brightness-gamma-correction]
       Mat lookUpTable(1, 256, CV_8U);
       uchar* p = lookUpTable.ptr();
       for (int i = 0; i < 256; ++i)
           p[i] = saturate_cast<uchar>(pow(i / 255.0, gamma_) * 255.0);

       Mat res = img.clone();
       LUT(img, lookUpTable, res);
       //! [changing-contrast-brightness-gamma-correction]

       hconcat(img, res, img_gamma_corrected);
       imshow("Gamma correction", img_gamma_corrected);
   }

   void on_linear_transform_alpha_trackbar(int, void *)
   {
       double alpha_value = alpha / 100.0;
       int beta_value = beta - 100;
       basicLinearTransform(img_original, alpha_value, beta_value);
   }

   void on_linear_transform_beta_trackbar(int, void *)
   {
       double alpha_value = alpha / 100.0;
       int beta_value = beta - 100;
       basicLinearTransform(img_original, alpha_value, beta_value);
   }

   void on_gamma_correction_trackbar(int, void *)
   {
       double gamma_value = gamma_cor / 100.0;
       gammaCorrection(img_original, gamma_value);
   }
}

int main(int argc, char** argv)
{
   CommandLineParser parser(argc, argv, "{@input |F://opencv//VS//demo//data//lena.jpg | input image}");
   img_original = imread(parser.get<String>("@input"));
   if (img_original.empty())
   {
       cout << "Could not open or find the image!\n" << endl;
       cout << "Usage: " << argv[0] << " <Input image>" << endl;
       return -1;
   }

   img_corrected = Mat(img_original.rows, img_original.cols * 2, img_original.type());
   img_gamma_corrected = Mat(img_original.rows, img_original.cols * 2, img_original.type());

   hconcat(img_original, img_original, img_corrected);
   hconcat(img_original, img_original, img_gamma_corrected);

   namedWindow("Brightness and contrast adjustments");
   namedWindow("Gamma correction");

   createTrackbar("Alpha gain (contrast)", "Brightness and contrast adjustments", &alpha, 500, on_linear_transform_alpha_trackbar);
   createTrackbar("Beta bias (brightness)", "Brightness and contrast adjustments", &beta, 200, on_linear_transform_beta_trackbar);
   createTrackbar("Gamma correction", "Gamma correction", &gamma_cor, 200, on_gamma_correction_trackbar);

   on_linear_transform_alpha_trackbar(0, 0);
   on_gamma_correction_trackbar(0, 0);

   waitKey();

   imwrite("linear_transform_correction.png", img_corrected);
   imwrite("gamma_correction.png", img_gamma_corrected);

   return 0;
}

运行：

OPENCV 在线修正图像参数