图像去雾

//
//  Created by swenw on 2019/10/30.
//  Copyright © 2019 swenw. All rights reserved.
//

#include <opencv2/opencv.hpp>
#include <opencv2/ximgproc/edge_filter.hpp>
using namespace cv;
using namespace std;

const float kernRatio=0.01; //自适应核比例
const float w=0.95; //w系数 用来调节
const float min_t =0.5; //最小透射率
void minFilter(Mat src, Mat &dst, int ksize);

int main(int argc, char *argv[])
{
    Mat src = imread("/Users/swenw/Documents/数字媒体技术/Image/3.png");
    imshow("src",src);
    
    //最小RGB
    Mat minRgb = Mat::zeros(src.rows,src.cols,CV_8UC1);
    for(int i=0;i<src.rows;i++){
        for(int j=0;j<src.cols;j++)
        {
            uchar g_minvalue =255;
            for(int c=0;c<3;c++)
            {
                if(g_minvalue>src.at<Vec3b>(i,j)[c])
                    g_minvalue=src.at<Vec3b>(i,j)[c];
            }
            minRgb.at<uchar>(i,j)=g_minvalue;
        }
    }
    
    //对RGB进行最小值滤波，获得暗通道
    Mat darkChannel;
    int ksize=max(3,max((int)(src.cols*kernRatio),(int)(src.rows*kernRatio)));
    minFilter(minRgb, darkChannel, ksize);
    
    //求大气A，A为含雾图像的像素的最大值
    double A;
    Point maxLoc;
    minMaxLoc(darkChannel, 0, 0, 0, &maxLoc);
    A=max(src.at<Vec3b>(maxLoc.y,maxLoc.x)[0],
          max(src.at<Vec3b>(maxLoc.y,maxLoc.x)[1],
              src.at<Vec3b>(maxLoc.y,maxLoc.x)[2]));
    
    //求透射率t=1-w*(darkChannel/A)
    //当I非常接近于A时，t会非常的小，t<mint_t，于是会出现比较多的色斑色偏
    //对t进行修正，
    Mat trans=Mat::zeros(src.rows,src.cols,CV_32FC1);
    uchar pix[3];
    for(int i=0; i<src.rows; i++){
        const uchar* inData = darkChannel.ptr<uchar>(i);
        const uchar* srcData = src.ptr<uchar>(i);
        float* outData = trans.ptr<float>(i);
        for(int j=0; j<src.cols; j++){
            pix[0]=*srcData++;
            pix[1]=*srcData++;
            pix[2]=*srcData++;
            uchar t=fabs((pix[0]+pix[1]+pix[2])/3.0-A);
            if(t<min_t) //当像素接近于大气光强时，加一个增幅量，使其不总比min_t小
                *outData++=1-w*(*inData++/A)+(min_t-t)/min_t;
            else
                *outData++=1-w*(*inData++/A);
        }
    }
    Mat t = Mat::zeros(src.rows,src.cols,CV_32FC1);
    //导向图滤波
    ximgproc::guidedFilter(src, trans, t, 0.25, 0.001);
    imshow("t", t);
    
    //J=(I-A)/max(t,min_t)+A
    Mat deFog=Mat::zeros(src.rows,src.cols,CV_8UC3);
    for(int i=0;i<src.rows;i++){
        for(int j=0;j<src.cols;j++){
            for(int k=0;k<src.channels();k++){ deFog.at<Vec3b>(i,j)[k]=saturate_cast<uchar>((src.at<Vec3b>(i,j)[k]-A)/max(t.at<float>(i,j), min_t)+A);
            }
        }
    }
    
    imshow("defog",deFog);
    while(char(waitKey(1))!=‘q‘){}
}

void minFilter(const Mat src,Mat &dst,int ksize)
{
    if(src.channels()!=1)
        return;
    if(src.depth()>8)
        return;
    
    int r=(ksize-1)/2; //核半径
    
    dst=Mat::zeros(src.rows,src.cols,CV_8UC1);
    for(int i=0; i<src.rows; i++){
        for(int j=0; j<src.cols; j++)
        {
            //初始化滤波核的上下左右边界
            int top=i-r;
            int bottom=i+r;
            int left=j-r;
            int right=j+r;
            
            //检查滤波核是否超出边界
            if(i-r<0)
                top=0;
            if(i+r>src.rows)
                bottom=src.rows;
            if(j-r<0)
                left=0;
            if(j+r>src.cols)
                right=src.cols;
            
            //求取模板下的最小值
            Mat ImROI=src(Range(top,bottom),Range(left,right));
            double min;
            minMaxLoc(ImROI, &min, 0, 0, 0);
            dst.at<uchar>(i,j)=min;
        }
    }
}