算法原理

https://www.cnblogs.com/Imageshop/archive/2013/04/20/3032062.html 在Imageshop前辈看到了这个完美反射算法用于自动白平衡的算法，此算法的原理是：完美反射理论假设图像中最亮的点就是白点，并以此白点为参考对图像进行自动白平衡，最亮点定义为R+G+B的最大值

算法步骤

  • 计算每个像素R,G,B之后，并保存
  • 按照R+G+B的值的大小计算出其前10%或其他Ratio的白色参考点的阈值T
  • 遍历图像中的每个点，计算其中R+G+B值大于T的所有点的R\G\B分量的累积和的平均值
  • 将每个像素量化到[0, 255]

C++源码实现

#include <stdio.h>
#include <iostream>
#include <immintrin.h>
#include <opencv2/opencv.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/ml/ml.hpp>
#include "opencv2/highgui/highgui.hpp"
using namespace cv;
using namespace cv::ml;
using namespace std;

Mat PerfectReflectionAlgorithm(Mat src) {
	int row = src.rows;
	int col = src.cols;
	Mat dst(row, col, CV_8UC3);
	int HistRGB[767] = { 0 };
	int MaxVal = 0;
	for (int i = 0; i < row; i++) {
		for (int j = 0; j < col; j++) {
			MaxVal = max(MaxVal, (int)src.at<Vec3b>(i, j)[0]);
			MaxVal = max(MaxVal, (int)src.at<Vec3b>(i, j)[1]);
			MaxVal = max(MaxVal, (int)src.at<Vec3b>(i, j)[2]);
			int sum = src.at<Vec3b>(i, j)[0] + src.at<Vec3b>(i, j)[1] + src.at<Vec3b>(i, j)[2];
			HistRGB[sum]++;
		}
	}
	int Threshold = 0;
	int sum = 0;
	for (int i = 766; i >= 0; i--) {
		sum += HistRGB[i];
		if (sum > row * col * 0.1) {
			Threshold = i;
			break;
		}
	}
	int AvgB = 0;
	int AvgG = 0;
	int AvgR = 0;
	int cnt = 0;
	for (int i = 0; i < row; i++) {
		for (int j = 0; j < col; j++) {
			int sumP = src.at<Vec3b>(i, j)[0] + src.at<Vec3b>(i, j)[1] + src.at<Vec3b>(i, j)[2];
			if (sumP > Threshold) {
				AvgB += src.at<Vec3b>(i, j)[0];
				AvgG += src.at<Vec3b>(i, j)[1];
				AvgR += src.at<Vec3b>(i, j)[2];
				cnt++;
			}
		}
	}
	AvgB /= cnt;
	AvgG /= cnt;
	AvgR /= cnt;
	for (int i = 0; i < row; i++) {
		for (int j = 0; j < col; j++) {
			int Blue = src.at<Vec3b>(i, j)[0] * MaxVal / AvgB;
			int Green = src.at<Vec3b>(i, j)[1] * MaxVal / AvgG;
			int Red = src.at<Vec3b>(i, j)[2] * MaxVal / AvgR;
			if (Red > 255) {
				Red = 255;
			}
			else if (Red < 0) {
				Red = 0;
			}
			if (Green > 255) {
				Green = 255;
			}
			else if (Green < 0) {
				Green = 0;
			}
			if (Blue > 255) {
				Blue = 255;
			}
			else if (Blue < 0) {
				Blue = 0;
			}
			dst.at<Vec3b>(i, j)[0] = Blue;
			dst.at<Vec3b>(i, j)[1] = Green;
			dst.at<Vec3b>(i, j)[2] = Red;
		}
	}
	return dst;
}

int main() {
	Mat src = imread("F:\\child.jpg");
	Mat dst = PerfectReflectionAlgorithm(src);
	imshow("origin", src);
	imshow("result", dst);
	imwrite("F:\\res.jpg", dst);
	waitKey(0);
}

效果