basic_linear_transforms.cpp

#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <iostream>

using namespace cv;

double alpha; /**< Simple contrast control */
int beta;  /**< Simple brightness control */

int main( int argc, char** argv )
{
    /// Read image given by user
    Mat image = imread( argv[1] );
    Mat new_image = Mat::zeros( image.size(), image.type() );

    /// Initialize values
    std::cout << " Basic Linear Transforms " << std::endl;
    std::cout << "-------------------------" << std::endl;
    std::cout << "* Enter the alpha value [1.0-3.0]: ";
    std::cin >> alpha;
    std::cout << "* Enter the beta value [0-100]: ";
    std::cin >> beta;

    /// Do the operation new_image(i,j) = alpha*image(i,j) + beta
    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 );
            }
        }
    }

    /// Create Windows
    namedWindow("Original Image", 1);
    namedWindow("New Image", 1);

    /// Show stuff
    imshow("Original Image", image);
    imshow("New Image", new_image);

    /// Wait until user press some key
    waitKey();
    return 0;
}