/**//// <summary>
        /// 变成黑白图
        /// </summary>
        /// <param name="bmp">原始图</param>
        /// <param name="mode">模式。0:加权平均  1:算数平均</param>
        /// <returns></returns>
        private Bitmap ToGray(Bitmap bmp,int mode)
        ...{
            if (bmp == null)
            ...{
                return null;
            }

            int w = bmp.Width;
            int h = bmp.Height;
            try
            ...{
                byte newColor = 0;
                BitmapData srcData = bmp.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
                unsafe
                ...{
                    byte* p = (byte*)srcData.Scan0.ToPointer();
                    for (int y = 0; y < h; y++)
                    ...{
                        for (int x = 0; x < w; x++)
                        ...{

                            if (mode == 0)　// 加权平均
                            ...{
                                newColor = (byte)((float)p[0] * 0.114f + (float)p[1] * 0.587f + (float)p[2] * 0.299f);
                            }
                            else　　　　// 算数平均
                            ...{
                                newColor = (byte)((float)(p[0] + p[1] + p[2]) / 3.0f);
                            }
                            p[0] = newColor;
                            p[1] = newColor;
                            p[2] = newColor;

                            p += 3;
                        }
                        p += srcData.Stride - w * 3;
                    }
                    bmp.UnlockBits(srcData);
                    return bmp;
                }
            }
            catch
            ...{
                return null;
            }

        }