private int getPixels(Bitmap bmpobj)
        {
            int[,] data = new int[1920, 1200];
            int max = 0;
            for (int i = 0; i < bmpobj.Height; i++)
            {
                for (int j = 0; j < bmpobj.Width; j++)
                {
                    Color b = bmpobj.GetPixel(j, i);
                    if (max < b.R)
                    {
                        max = b.R;
                    }
                }
            }
            return max;
        }

private int GetImgInfo(Bitmap a)
        {
            Bitmap src = new Bitmap(a);
            int w = src.Width;
            int h = src.Height;
            int max = 0;
            BitmapData srcData = src.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
            unsafe
            {
                byte* p = (byte*)srcData.Scan0;
                int gray = 0;
                for (int j = 1; j < h - 1; j++)
                {
                    for (int i = 1; i < w - 1; i++)
                    {
                        gray = p[0] ;//+= (p[0] + p[1] + p[2]) / 3;
                        p += 4;
                        if (max < gray)
                        {
                            max = gray;
                        }
                    }
                    p += srcData.Stride - w * 4;
                }
                src.UnlockBits(srcData);
                return  max ;
            }
        }

  private Bitmap drawPic(byte[] srcdata, int width, int height)
        {
            // 8bit索引方式位图，设置灰度调色板
            var fmt = PixelFormat.Format8bppIndexed;
            var bmp = new Bitmap(width, height, fmt);
            var palette = bmp.Palette;
            for (var i = 0; i < 256; i++)
            {
                palette.Entries[i] = Color.FromArgb(i, i, i);
            }
            bmp.Palette = palette;

            // 把数据映射到256灰度，unsafe填充到位图
            var bmpData = bmp.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, fmt);
            unsafe
            {
                var p = (byte*)bmpData.Scan0;
                for (var i = 0; i < srcdata.Length; i++)
                {
                    *p = (byte)(srcdata[i]);
                    p++;
                }
            }
            bmp.UnlockBits(bmpData);
            return bmp;
        }

public unsafe byte[] ToArray(Bitmap b)
        {
            BitmapData data = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadOnly, b.PixelFormat);
            int height = data.Height;
            int stride = data.Stride;

            IntPtr ptr = data.Scan0;
            int scanBytesLength = stride * height;

            byte[] rgbValues = new byte[scanBytesLength];
            unsafe
            {
                Marshal.Copy(ptr, rgbValues, 0, scanBytesLength);
            }
            b.UnlockBits(data);
            return rgbValues;
        }