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/**
* @file BasicLinearTransformsTrackbar.cpp
* @brief Simple program to change contrast and brightness
* @date Mon, June 6, 2011
* @author OpenCV team
*/
#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 namespace cv;
/** Global Variables */
const int alpha_max = 5;
const int beta_max = 125;
int alpha; /**< Simple contrast control */
int beta; /**< Simple brightness control*/
/** Matrices to store images */
Mat image;
/**
* @function on_trackbar
* @brief Called whenever any of alpha or beta changes
*/
static void on_trackbar( int, void* )
{
Mat new_image = Mat::zeros( image.size(), image.type() );
for( int y = 0; y < image.rows; y++ )
for( int x = 0; x < image.cols; x++ )
for( int c = 0; c < 3; c++ )
new_image.at<Vec3b>(y,x)[c] = saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta );
imshow("New Image", new_image);
}
/**
* @function main
* @brief Main function
*/
int main( int argc, char** argv )
{
/// Read image given by user
String imageName("lena.jpg"); // by default
if (argc > 1)
{
imageName = argv[1];
}
image = imread( samples::findFile( imageName ) );
/// Initialize values
alpha = 1;
beta = 0;
/// Create Windows
namedWindow("Original Image", 1);
namedWindow("New Image", 1);
/// Create Trackbars
createTrackbar( "Contrast", "New Image", &alpha, alpha_max, on_trackbar );
createTrackbar( "Brightness", "New Image", &beta, beta_max, on_trackbar );
/// Show some stuff
imshow("Original Image", image);
imshow("New Image", image);
/// Wait until user press some key
waitKey();
return 0;
}
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