Change Brightness of an Image

Steps to Change Brightness of an Image | OpenCV with Visual Studio in Windows 10. In this Tutorial, we are going to increase and decrease brightness of an image using OpenCV.

1. First of all, Follow this tutorial to Install & Configure OpenCV with Visual Studio 2015


2. Copy the Full Source Code to Change Brightness of an Image from here:

#include<opencv2/highgui/highgui.hpp>

using namespace cv;

int main()
{
 //Load an Image
 Mat img = imread("C:/Briefcase/Chess.jpg", CV_LOAD_IMAGE_COLOR);
 namedWindow("Image", CV_WINDOW_AUTOSIZE);
 imshow("Image", img);

 //Change Brightness Effect
 Mat imgInc;
 img.convertTo(imgInc, -1, 1, 25);  //increase brightness by 25 units    

 Mat imgDec;
 img.convertTo(imgDec, -1, 1, -25);  //decrease brightness by 25 units

 namedWindow("Inc Brightness", CV_WINDOW_AUTOSIZE);
 namedWindow("Dec Brightness", CV_WINDOW_AUTOSIZE);

 imshow("Inc Brightness", imgInc);
 imshow("Dec Brightness", imgDec);

 //Wait Key press
 cvWaitKey(0);

 //destroy windows
 destroyAllWindows();
 return 0;
}

OR
Get ChangeBrightness.cpp from Github:
Download ChangeBrightness.cpp


3. Paste full source code and Run it (Ctrl+F5 or F5).

OUTPUT

Load Image OpenCV

Increase Brightness of an Image - OpenCV

Decrease Brightness of an Image - OpenCV

Explaination :
Function used: 
img.convertTo(imgInc, -1, 1, 25) - This function can process images and increase brightness by 25 units.
img.convertTo(imgDec, -1, 1, -25) - This function can process images and decrease brightness by 25 units.

• 1^st parameter is the output matrix.
• 2^nd parameter is Depth of the output image. If rtype is negative, output type is same as the input type.
• 3^rd parameter is the multiplication or scaling factor, every pixel will be multiplied by this value.
• 4^th parameter is delta factor added to the scaled values.

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