1. 灰度变换

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#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main() 
{
    
    Mat img,out_img,img_gray;
    img = imread("/home/v/home.png");
    if (img.empty()){
        cout << "Could not open or find the image" << endl;
        return -1;
    }

    cvtColor(img, img_gray, COLOR_BGR2GRAY);
    imshow("img gray",img_gray); 

    out_img = img_gray.clone();
    for (int i=0;i<img_gray.rows;i++){
        for (int j=0;j<img_gray.cols;j++){
            // 灰度翻转
            out_img.at<uchar>(i,j) = 255 - img_gray.at<uchar>(i,j); 
        }
    }
    
    imshow("灰度翻转",out_img);
    waitKey(0);
    return 0;
    
}

2. 对数变换

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#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;


int main() 
{
    
    Mat img,out_img,img_gray;
    img = imread("/home/v/home.png");
    if (img.empty()){
        cout << "Could not open or find the image" << endl;
        return -1;
    }

    cvtColor(img, img_gray, COLOR_BGR2GRAY);
    imshow("img gray",img_gray); 

    out_img = img_gray.clone();
    for (int i=0;i<img_gray.rows;i++){
        for (int j=0;j<img_gray.cols;j++){
            // 对数变换6*log(r+1) 伽马变换
            out_img.at<uchar>(i,j) = 6*log((double)(img_gray.at<uchar>(i,j)) + 1);
        }
    }

    normalize(out_img,out_img,0,255,NORM_MINMAX); // 图像归一化
    convertScaleAbs(out_img,out_img); // 数据类型转换到CV_8U
    
    imshow("对数变换",out_img);
    waitKey(0);
    return 0;
    
}

3. 伽马变换

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#include <iostream>
#include <opencv2/opencv.hpp>


using namespace std;
using namespace cv;


int main() 
{
    
    Mat img,out_img,img_gray;
    img = imread("/home/v/home.png");
    if (img.empty()){
        cout << "Could not open or find the image" << endl;
        return -1;
    }

    cvtColor(img, img_gray, COLOR_BGR2GRAY);
    imshow("img gray",img_gray); 

    out_img = img_gray.clone();
    for (int i=0;i<img_gray.rows;i++){
        for (int j=0;j<img_gray.cols;j++){
            // 伽马变换6*r^0.5
            out_img.at<uchar>(i,j) = 6*pow((double)(img_gray.at<uchar>(i,j)),0.5);
        }
    }

    normalize(out_img,out_img,0,255,NORM_MINMAX); // 图像归一化
    convertScaleAbs(out_img,out_img); // 数据类型转换到CV_8U
    
    imshow("伽马变换",out_img);
    waitKey(0);
    return 0;
    
}