//木刻效果public Bitmap PFilterMuKe(Bitmap src){ try {  Bitmap a = new Bitmap(src);  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;   int temp = 0;   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];    temp = (byte)((B + G + R) / 3);    if (temp >= 122.5)    {    P[2] = 0;    P[1] = 0;    P[0] = 0;    }    else    {    P[2] = (byte)255;    P[1] = (byte)255;    P[0] = (byte)255;    }    pIn += 3;   }   pIn += stride - a.Width * 3;   }  }  a.UnlockBits(bmpData);  return a; } catch (Exception e) {  MessageBox.Show(e.Message.ToString());  return null; }}