opencv 提高图像对比度

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

using namespace cv;

int main(int argc, char** argv) {
    Mat src, dst;
    src = imread("D:/vcprojects/images/test.jpg");
    if (!src.data) {
        printf("could not load image...\n");
        return -1;
    }
    namedWindow("input image", CV_WINDOW_AUTOSIZE);
    imshow("input image", src);

    double t = getTickCount();
    
#if 1
    int cols = (src.cols-1) * src.channels();
    int offsetx = src.channels();
    int rows = src.rows;

    dst = Mat::zeros(src.size(), src.type());
    for (int row = 1; row < (rows - 1); row++) {
        const uchar* previous = src.ptr<uchar>(row - 1);
        const uchar* current = src.ptr<uchar>(row);
        const uchar* next = src.ptr<uchar>(row + 1);
        uchar* output = dst.ptr<uchar>(row);
        for (int col = offsetx; col < cols; col++) {
            output[col] = saturate_cast<uchar>(
                5 * current[col] - (current[col- offsetx] + current[col+ offsetx] + previous[col] + next[col])
                );
        }
    }
#else
    /*
    */
    Mat kernel = (Mat_<char>(3, 3) << 0, -1, 0, -1, 5, -1, 0, -1, 0);
    filter2D(src, dst, src.depth(), kernel);
#endif
    
    double timeconsume = (getTickCount() - t) / getTickFrequency();
    printf("tim consume %.2f\n", timeconsume);

    namedWindow("contrast image demo", CV_WINDOW_AUTOSIZE);
    imshow("contrast image demo", dst);

    waitKey(0);
    return 0;

}