1 #include <opencv2\opencv.hpp>
  2 #include <iostream>
  3 #include <string>
  4 
  5 using namespace cv;
  6 using namespace std;
  7 
  8 //計算亮度中值和灰度<=中值的畫素點個數
  9 void CalculateImage_MedianGray_PixelCount(const Mat &histogram, int pixelCount, int &medianValue, int &pixleCountLowerMedian)
 
 10 {
 11     float *data = (float *)histogram.data;//直方圖
 12     int sum = 0;
 13     for (int i = 0; i <= 255; ++i)
 14     {
 15         //
 16         sum += data[i];
 17         if (2 * sum>pixelCount)
 18         {
 19             medianValue = i;
 20             pixleCountLowerMedian = sum;
 21
 
             break;
 22         }
 23     }
 24 }
 25 
 26 void fastMedianBlur(const Mat &srcImg, Mat &dstImg, int diameter)
 27 {
 28     int radius = (diameter - 1) / 2;
 29     int imgW = srcImg.cols;
 30     int imgH = srcImg.rows;
 31     int channels = srcImg.channels();
 32     dstImg = Mat::zeros(imgH, imgW, CV_8UC1);
 
 33     int windowSize = diameter*diameter;
 34     Mat windowImg = Mat::zeros(diameter, diameter, CV_8UC1);
 35 
 36     //直方圖
 37     Mat histogram;
 38     int histogramSize = 256;//灰度等級
 39     int thresholdValue = windowSize / 2 + 1;//step1.設定閾值(步驟參考：影象的高效程式設計要點之四)
 40 
 41     //待處理影象畫素
 42     uchar *pDstData = dstImg.data + imgW*radius + radius;
 43     //整個影象中視窗位置指標
 44     uchar *pSrcData = srcImg.data;
 45 
 46     //逐行遍歷
 47     for (int i = radius; i <= imgH - 1 - radius; i++)
 48     {
 49         //列指標
 50         uchar *pColDstData = pDstData;
 51         uchar *pColSrcData = pSrcData;
 52 
 53         //單個視窗指標
 54         uchar *pWindowData = windowImg.data;
 55         uchar *pRowSrcData = pColSrcData;
 56         //從源圖中提取視窗影象
 57         for (int winy = 0; winy <= diameter - 1; winy++)
 58         {
 59             for (int winx = 0; winx <= diameter - 1; winx++)
 60             {
 61                 pWindowData[winx] = pRowSrcData[winx];
 62             }
 63             pRowSrcData += imgW;
 64             pWindowData += diameter;
 65         }
 66 
 67         //求直方圖,確定中值，並記錄亮度<=中值的畫素點個數
 68         calcHist(&windowImg,
 69             1,//Mat的個數
 70             0,//用來計算直方圖的通道索引，通道索引依次排開
 71             Mat(),//Mat()返回一個空值，表示不用mask,
 72             histogram, //直方圖
 73             1, //直方圖的維數，如果計算2個直方圖，就為2
 74             &histogramSize, //直方圖的等級數(如灰度等級),也就是每列的行數
 75             0//分量的變化範圍
 76         );
 77 
 78         //求亮度中值和<=中值的畫素點個數
 79         int medianValue, pixelCountLowerMedian;
 80         CalculateImage_MedianGray_PixelCount(histogram, windowSize, medianValue, pixelCountLowerMedian);
 81         ////////////滑動視窗操作結束///////////////////////
 82 
 83         //濾波
 84         pColDstData[0] = (uchar)medianValue;
 85 
 86         //處理同一行下一個畫素
 87         pColDstData++;
 88         pColSrcData++;
 89         for (int j = radius + 1; j <= imgW - radius - 1; j++)
 90         {
 91             //維護滑動視窗直方圖
 92             //刪除左側
 93             uchar *pWinLeftData = pColSrcData - 1;
 94             float *pHistData = (float*)histogram.data;
 95             for (int winy = 0; winy < diameter; winy++)
 96             {
 97                 uchar grayValue = pWinLeftData[0];
 98                 pHistData[grayValue] -= 1.0;
 99                 if (grayValue <= medianValue)
100                 {
101                     pixelCountLowerMedian--;
102                 }
103                 pWinLeftData += imgW;
104             }
105 
106             //增加右側
107             uchar *pWinRightData = pColSrcData + diameter - 1;
108             for (int winy = 0; winy < diameter; winy++)
109             {
110                 uchar grayValue = pWinRightData[0];
111                 pHistData[grayValue] += 1.0;
112                 if (grayValue <= medianValue)
113                 {
114                     pixelCountLowerMedian++;
115                 }
116                 pWinRightData += imgW;
117             }
118             //計算新的中值
119             if (pixelCountLowerMedian > thresholdValue)
120             {
121                 while (1)
122                 {
123                     pixelCountLowerMedian -= pHistData[medianValue];
124                     medianValue--;
125                     if (pixelCountLowerMedian <= thresholdValue)
126                     {
127                         break;    
128                     }
129                 }
130             }
131             else 
132             {
133                 while (pixelCountLowerMedian < thresholdValue)
134                 {
135                     medianValue++;
136                     pixelCountLowerMedian += pHistData[medianValue];
137 
138                 }
139             }
140 
141             pColDstData[0] = medianValue;
142             //下一個畫素
143             pColDstData++;
144             pColSrcData++;
145         }
146         //移動至下一行
147         pDstData += imgW;
148         pSrcData += imgW;
149     }
150 
151     //邊界直接賦原始值，不做濾波處理
152     pSrcData = srcImg.data;
153     pDstData = dstImg.data;
154     //上下邊界
155     for (int j = 0; j < imgW; j++)
156     {
157         for (int i = 0; i < radius; i++)
158         {
159             int idxTop = i*imgW + j;
160             pDstData[idxTop] = pSrcData[idxTop];
161             int idxBot = (imgH - i - 1)*imgW + j;
162             pDstData[idxBot] = pSrcData[idxBot];
163         }
164     }
165     //左右邊界
166     for (int i = radius; i < imgH - radius - 1; i++)
167     {
168         for (int j = 0; j < radius; j++)
169         {
170             int idxLeft = i*imgW + j;
171             pDstData[idxLeft] = pSrcData[idxLeft];
172             int idxRight = i*imgW + imgW - j-1;
173             pDstData[idxRight] = pSrcData[idxRight];
174         }
175     }
176 }
177 
178 
179 void main()
180 {
181     string imgPath = "data/";
182     Mat srcImg = imread(imgPath + "moon.jpg", 0);
183     Mat dstImg;
184     double t0 = cv::getTickCount();
185     fastMedianBlur(srcImg, dstImg, 5);
186     //cv::medianBlur(srcImg, dstImg, 5); //OpenCV
187     double t1 = cv::getTickCount();
188     cout << "time=" << (t1 - t0) / cv::getTickFrequency() << endl;
189     
190     imwrite("data/test/srcImg.bmp", srcImg);
191     imwrite("data/test/myFilter.bmp", dstImg);
192 }