OpenCV学习：改变图像的对比度和亮度

　　本实例演示简单地改变图像的对比度和亮度，使用了如下线性变换来实现像素值的遍历操作：

　　

　　The parameters α > 0 and β often called the gain and bias parameters;

　　sometimes these parameters are said to control contrast and brightness respectively.

　　代码如下：

// 改变图像的对比度和亮度  
#include <opencv2/opencv.hpp>  
using namespace cv;
using namespace std;

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

int main( int argc, char** argv )
{
    /// 加载图像
    Mat image = imread( "./Res/James Harden.jpg" );

　　/// 目标图像空间预分配
    Mat new_image = Mat::zeros( image.size(), image.type() );

    /// 输入初始化值
    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;
    /// 执行变换 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 );
            }
        }
    }
    /// 创建显示窗口
    namedWindow("Original Image", 1);
    namedWindow("New Image", 1);

    /// 显示图像
    imshow("Original Image", image);
    imshow("New Image", new_image);

    /// 等待键盘事件
    waitKey();

    cin.get();
    return 0;
}

运行结果：