//OSTU求图像的阈值

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

 {

 //    int width = frame->width;

 //    int height = frame->height;

     u16 pixelCount[];

     float pixelPro[];

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

     //遍历灰度级[0,255]

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

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

     for(i = ; i < ; i++)

     {

         pixelCount[i] = ;

         pixelPro[i] = ;

     }

     //统计灰度级中每个像素在整幅图像中的个数

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

     {

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

         {

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

         }

     }

     //计算每个像素在整幅图像中的比例

     for(i = ; i < ; i++)

     {

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

     }

     for(i = ; i < ; i++)

     {

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

         for(j = ; j < ; j++)

         {

             if(j <= i)   //背景部分

             {

                 w0 += pixelPro[j];

                 u0tmp += j * pixelPro[j];

             }

             else   //前景部分

             {

                 w1 += pixelPro[j];

                 u1tmp += j * pixelPro[j];

             }

         }

         u0 = u0tmp / w0;

         u1 = u1tmp / w1;

         u = u0tmp + u1tmp;

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

         if(deltaTmp > deltaMax)

         {

             deltaMax = deltaTmp;

             threshold = i;

         }

     }

     return threshold;

 }