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/**
* @file BasicLinearTransforms.cpp
* @brief Simple program to change contrast and brightness
* @author OpenCV team
*/
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include <iostream>
// we're NOT "using namespace std;" here, to avoid collisions between the beta variable and std::beta in c++17
using std::cin;
using std::cout;
using std::endl;
using namespace cv;
/**
* @function main
* @brief Main function
*/
int main( int argc, char** argv )
{
/// Read image given by user
//! [basic-linear-transform-load]
CommandLineParser parser( argc, argv, "{@input | lena.jpg | input image}" );
Mat image = imread( samples::findFile( parser.get<String>( "@input" ) ) );
if( image.empty() )
{
cout << "Could not open or find the image!\n" << endl;
cout << "Usage: " << argv[0] << " <Input image>" << endl;
return -1;
}
//! [basic-linear-transform-load]
//! [basic-linear-transform-output]
Mat new_image = Mat::zeros( image.size(), image.type() );
//! [basic-linear-transform-output]
//! [basic-linear-transform-parameters]
double alpha = 1.0; /*< Simple contrast control */
int beta = 0; /*< Simple brightness control */
/// Initialize values
cout << " Basic Linear Transforms " << endl;
cout << "-------------------------" << endl;
cout << "* Enter the alpha value [1.0-3.0]: "; cin >> alpha;
cout << "* Enter the beta value [0-100]: "; cin >> beta;
//! [basic-linear-transform-parameters]
/// Do the operation new_image(i,j) = alpha*image(i,j) + beta
/// Instead of these 'for' loops we could have used simply:
/// image.convertTo(new_image, -1, alpha, beta);
/// but we wanted to show you how to access the pixels :)
//! [basic-linear-transform-operation]
for( int y = 0; y < image.rows; y++ ) {
for( int x = 0; x < image.cols; x++ ) {
for( int c = 0; c < image.channels(); c++ ) {
new_image.at<Vec3b>(y,x)[c] =
saturate_cast<uchar>( alpha*image.at<Vec3b>(y,x)[c] + beta );
}
}
}
//! [basic-linear-transform-operation]
//! [basic-linear-transform-display]
/// Show stuff
imshow("Original Image", image);
imshow("New Image", new_image);
/// Wait until the user press a key
waitKey();
//! [basic-linear-transform-display]
return 0;
}
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