[OpenCV] 图像亮度和对比度调整

对比度调整的原理参考这篇博客

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;

}