Otsu

 1 int Otsu_local(Mat src)
 2 {
 3     int hist[256] = { 0 };
 4     int IMGH = src.rows;
 5     int IMGW = src.cols;
 6     
 7     for (int i = 0; i < IMGH; i++)
 8     {
 9         for (int j = 0; j < IMGW; j++)
10         {
11             hist[int(src.at<uchar>(i,j))]++;
12         }
13     }
14     float w0 ; 
15     float w1 ;
16     float u0 ;
17     float u1 ;
18     float maxvar = 0;
19     int T;
20     for (int k = 0; k < 256; k++)
21     {
22          w0 = 0;
23          w1 = 0;
24          u0 = 0;
25          u1 = 0;
26          for (int i = 0; i < k; i++)
27          {
28              w0 += hist[i];
29              u0 += i*hist[i];
30          }
31          for (int j = k; j < 256; j++)
32          {
33              w1 += hist[j];
34              u1 += j*hist[j];
35          }
36 
37          w0 /= (IMGW*IMGH);
38          w1 /= (IMGW*IMGH);
39          u0 /= w0;
40          u1 /= w1;
41         
42          float var = w0*w1*(u1 - u0)*(u1 - u0);
43          if (var > maxvar){
44              maxvar = var;
45              T = k;
46          }
47 
48     }
49     return T;
50 
51 }