How to add Track-bar in OpenCV using C++?

Track-bars are controllable bars which are used to control various parameters in OpenCV. Using track-bars, we can make it easier and change the parameters graphically. Track-bar removes this limitation and enables to create of dynamic effects using OpenCV.

The following program demonstrates how to add track-bars in OpenCV using C++.

Example

#include<iostream>
#include<opencv2/highgui/highgui.hpp>
using namespace cv;
using namespace std;
int main() {
   Mat original;//Declaring a matrix//
   original = imread("sky.jpg");//loading the image in the matrix//
   namedWindow("Slider");//Declaring window to show the image//
   int light = 50;//starting value of the trackbar//
   createTrackbar("Brightness", "Slider", &light, 100);//creating a trackbar//
   int contrast = 50;//starting value of the trackbar//
   createTrackbar("Contrast", "Slider", &contrast, 100);//creating a trackbar//
   while (true) {
      Mat edit;//declaring a matrix//
      int Brightness = light - 50;//interaction with trackbar//
      double Contrast = contrast / 50.0;//interaction with trackbar//
      original.convertTo(edit, -1, Contrast, Brightness);//implement the effect of change of trackbar//
      waitKey(50);
   }
   return(0);
}

Output

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Updated on: 10-Mar-2021

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