//定義膚色檢測函數（可供人臉檢測等研究使用）public Bitmap SkinDetect1(Bitmap a){  Rectangle rect = new Rectangle(0, 0, a.Width, a.Height);  System.Drawing.Imaging.BitmapData bmpData = a.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);  int stride = bmpData.Stride;  unsafe  {   byte* pIn = (byte*)bmpData.Scan0.ToPointer();   byte* P;   int R, G, B;   double r, g, Fupr,Flor,Wrg;   for (int y = 0; y < a.Height; y++)   {     for (int x = 0; x < a.Width; x++)     {     P = pIn;     B = P[0];     G = P[1];     R = P[2];     if (R + G + B == 0)     {       r = 0;       g = 0;     }     else     {       r = (R / (R + G + B));       g = (G / (R + G + B));     }     Fupr = (1.0743 * r + 0.1452-1.3767 * r * r) ;     Flor = (0.5601 * r + 0.1766-0.776 * r * r);     Wrg = (r - 0.33) * (r - 0.33) + (g - 0.33) * (g - 0.33);       if ((R - G >= 45) && ((R > G) && (G > B)) && (Fupr > g) && (Wrg >= 0.0004))     {        P[0] = (byte)B;        P[1] = (byte)G;        P[2] = (byte)R;       }     else     {       P[0] = 0;       P[1] = 0;       P[2] = 0;     }     pIn += 3;          }     pIn += stride - a.Width * 3;   }  }  a.UnlockBits(bmpData);  return a;}