[OpenCV] 图像亮度和对比度调整

我就是我 2021-12-20 05:27 305阅读 0赞

对比度调整的原理参考[这篇博客][Link 1]

以下是代码实现：

#include <iostream>
    #include "opencv2/core.hpp"
    #include "opencv2/imgproc.hpp"
    #include "opencv2/highgui.hpp"
    
    using namespace std;
    using namespace cv;
    
    #define CLIP_RANGE(value, min, max)  ( (value) > (max) ? (max) : (((value) < (min)) ? (min) : (value)) )
    #define COLOR_RANGE(value)  CLIP_RANGE(value, 0, 255)
    #define PI 3.1415926
    
    /*
    * Adjust Brightness and Contrast
    * @param src [in] InputArray
    * @param dst [out] OutputArray
    * @param brightness [in] integer, value range [-255, 255]
    * @param contrast [in] integer, value range [-255, 255]
    * @return 0 if success, else return error code
    */
    int adjustBrightnessContrast(Mat src, Mat& dst, int brightness, int contrast)
    {
    	if (src.empty()) {
    		return -1;
    	}
    
    	brightness = CLIP_RANGE(brightness, -255, 255);
    	contrast = CLIP_RANGE(contrast, -255, 255);
    
    	/*
    	Algorithm of Brightness Contrast transformation
    	The formula is:
    	y = [x - 127.5 * (1 - B)] * k + 127.5 * (1 + B);
    	x is the input pixel value;
    	y is the output pixel value;
    	B is brightness, value range is [-1,1];
    	k is used to adjust contrast;
    	k = tan( (45 + 44 * c) / 180 * PI );
    	c is contrast, value range is [-1,1];
    	especially:
    	when B = 0, y = (x-127.5)*k + 127.5, adjust Contrast only;
    	when c = 0, k = 1, y = x + 255*B, adjust Brightness only;
    	*/
    
    	double B = brightness / 255.;
    	double c = contrast / 255.;
    	double k = tan((45 + 44 * c) / 180 * PI);
    
    	Mat lookupTable(1, 256, CV_8U);
    	uchar *p = lookupTable.data;
    	for (int i = 0; i < 256; i++)
    		p[i] = COLOR_RANGE((i - 127.5 * (1 - B)) * k + 127.5 * (1 + B));
    
    	LUT(src, lookupTable, dst);
    
    	return 0;
    }
    
    
    //=====主程序开始====
    static Mat src;
    static int brightness = 255;
    static int contrast = 255;
    
    static void callbackAdjust(int, void *)
    {
    	Mat dst;
    	adjustBrightnessContrast(src, dst, brightness - 255, contrast - 255);
    	imshow("photo", dst);
    }
    
    int main()
    {
    	src = imread("D:\\1.jpg");
    
    	if (!src.data) {
    		cout << "error read image" << endl;
    		return -1;
    	}
    
    	namedWindow("photo");
    	createTrackbar("brightness", "photo", &brightness, 2 * brightness, callbackAdjust);
    	createTrackbar("contrast", "photo", &contrast, 2 * contrast, callbackAdjust);
    	callbackAdjust(0, 0);
    
    	waitKey();
    	destroyAllWindows();
    
    	return 0;
    }

![1235843-20190414153247875-2089344082.png][]

转载于:https://www.cnblogs.com/P3nguin/p/10705363.html

[Link 1]: http://blog.sina.com.cn/s/blog_7462bf390101f2bo.html
[1235843-20190414153247875-2089344082.png]: /images/20211220/5e385fb23eb94a278a64c6b995275463.png