//定义图像二值化函数
private static Bitmap PBinary(Bitmap src,int v)
{
 int w = src.Width;
 int h = src.Height;
 Bitmap dstBitmap = new Bitmap(src.Width ,src.Height ,System .Drawing .Imaging .PixelFormat .Format24bppRgb );
 System.Drawing.Imaging.BitmapData srcData = src.LockBits(new Rectangle(0, 0, w, h), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
 System.Drawing.Imaging.BitmapData dstData = dstBitmap.LockBits(new Rectangle(0, 0, w, h), System.Drawing.Imaging.ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
 unsafe
 {
  byte* pIn = (byte*)srcData.Scan0.ToPointer();
  byte* pOut = (byte*)dstData.Scan0.ToPointer();
  byte* p;
  int stride = srcData.Stride;
  int r, g, b;
  for (int y = 0; y < h; y++)
  {
  for (int x = 0; x < w; x++)
  {
   p = pIn;
   r = p[2];
   g = p[1];
   b = p[0];
   pOut [0]=pOut [1]=pOut [2]=(byte)(((byte)(0.2125 * r + 0.7154 * g + 0.0721 * b) >= v)
   ? 255 : 0);
   pIn += 3;
   pOut += 3;
  }
  pIn += srcData.Stride - w * 3;
  pOut += srcData.Stride - w * 3;
  }
  src.UnlockBits(srcData );
  dstBitmap.UnlockBits(dstData );
  return dstBitmap;
 }
}