[代码片段]OSTU算法

 用在片上系统上的

 1 //OSTU求图像的阈值

 2 u8 otsuThreshold(u8 **img, u16 height, u16 width)

 3 {

 4 //    int width = frame->width;

 5 //    int height = frame->height;

 6     u16 pixelCount[256];

 7     float pixelPro[256];

 8     u16 i, j, pixelSum = width * height, threshold = 0;

 9     //遍历灰度级[0,255]

10     float w0, w1, u0tmp, u1tmp, u0, u1, u, deltaTmp, deltaMax = 0;

11     //u8* data = (uchar*)frame->imageData;

12 

13     for(i = 0; i < 256; i++)

14     {

15         pixelCount[i] = 0;

16         pixelPro[i] = 0;

17     }

18 

19     //统计灰度级中每个像素在整幅图像中的个数

20     for(i = 0; i < height; i++)

21     {

22         for(j = 0;j < width;j++)

23         {

24             pixelCount[ img[i][j] ]++;

25         }

26     }

27     

28     //计算每个像素在整幅图像中的比例

29     for(i = 0; i < 256; i++)

30     {

31         pixelPro[i] = (float)pixelCount[i] / pixelSum;

32     }

33 

34     for(i = 0; i < 256; i++)

35     {

36         w0 = w1 = u0tmp = u1tmp = u0 = u1 = u = deltaTmp = 0;

37         for(j = 0; j < 256; j++)

38         {

39             if(j <= i)   //背景部分

40             {

41                 w0 += pixelPro[j];

42                 u0tmp += j * pixelPro[j];

43             }

44             else   //前景部分

45             {

46                 w1 += pixelPro[j];

47                 u1tmp += j * pixelPro[j];

48             }

49         }

50         u0 = u0tmp / w0;

51         u1 = u1tmp / w1;

52         u = u0tmp + u1tmp;

53         deltaTmp = w0 * pow((u0 - u), 2) + w1 * pow((u1 - u), 2);

54         if(deltaTmp > deltaMax)

55         {

56             deltaMax = deltaTmp;

57             threshold = i;

58         }

59     }

60 

61     return threshold;

62 }