OpenMetaverse.Imaging.OpenJPEG.EncodeFromImage C# (CSharp) Method

        public static unsafe byte[] EncodeFromImage(Bitmap bitmap, bool lossless)
        {
            BitmapData bd;
            ManagedImage decoded;

            int bitmapWidth = bitmap.Width;
            int bitmapHeight = bitmap.Height;
            int pixelCount = bitmapWidth * bitmapHeight;
            int i;

            if ((bitmap.PixelFormat & PixelFormat.Alpha) != 0 || (bitmap.PixelFormat & PixelFormat.PAlpha) != 0)
            {
                // Four layers, RGBA
                decoded = new ManagedImage(bitmapWidth, bitmapHeight,
                    ManagedImage.ImageChannels.Color | ManagedImage.ImageChannels.Alpha);
                bd = bitmap.LockBits(new Rectangle(0, 0, bitmapWidth, bitmapHeight),
                    ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
                byte* pixel = (byte*)bd.Scan0;

                for (i = 0; i < pixelCount; i++)
                {
                    // GDI+ gives us BGRA and we need to turn that in to RGBA
                    decoded.Blue[i] = *(pixel++);
                    decoded.Green[i] = *(pixel++);
                    decoded.Red[i] = *(pixel++);
                    decoded.Alpha[i] = *(pixel++);
                }
            }
            else if (bitmap.PixelFormat == PixelFormat.Format16bppGrayScale)
            {
                // One layer
                decoded = new ManagedImage(bitmapWidth, bitmapHeight,
                    ManagedImage.ImageChannels.Color);
                bd = bitmap.LockBits(new Rectangle(0, 0, bitmapWidth, bitmapHeight),
                    ImageLockMode.ReadOnly, PixelFormat.Format16bppGrayScale);
                byte* pixel = (byte*)bd.Scan0;

                for (i = 0; i < pixelCount; i++)
                {
                    // Normalize 16-bit data down to 8-bit
                    ushort origVal = (byte)(*(pixel) + (*(pixel + 1) << 8));
                    byte val = (byte)(((double)origVal / (double)UInt32.MaxValue) * (double)Byte.MaxValue);

                    decoded.Red[i] = val;
                    decoded.Green[i] = val;
                    decoded.Blue[i] = val;
                    pixel += 2;
                }
            }
            else
            {
                // Three layers, RGB
                decoded = new ManagedImage(bitmapWidth, bitmapHeight,
                    ManagedImage.ImageChannels.Color);
                bd = bitmap.LockBits(new Rectangle(0, 0, bitmapWidth, bitmapHeight),
                    ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
                byte* pixel = (byte*)bd.Scan0;

                for (i = 0; i < pixelCount; i++)
                {
                    decoded.Blue[i] = *(pixel++);
                    decoded.Green[i] = *(pixel++);
                    decoded.Red[i] = *(pixel++);
                }
            }

            bitmap.UnlockBits(bd);
            byte[] encoded = Encode(decoded, lossless);
            return encoded;
        }