BitmapSource到位图返回Null(EmguCV2.4.2.1777+Kinect)

Hy，我正在尝试将BitmapSource从Kinect RGB颜色流转换为位图。我变空了。我使用的是Kinect for Windows SDK 1.6、Visual Studio 2012、Windows 7 Ultimate 64位、EmguCV 2.4.2.1777。这是代码：

void _kinect_ColorFrameReady( object sender, ColorImageFrameReadyEventArgs e )
    {
        using ( ColorImageFrame colorFrame = e.OpenColorImageFrame() )
        {
            if ( colorFrame == null )
            {
                return;
            }
            if ( colorFrame != null )
            {
                this.colorPixels = new byte[colorFrame.PixelDataLength];
                colorFrame.CopyPixelDataTo( this.colorPixels );
                int stride = colorFrame.Width * 4;
                colorBmp = BitmapSource.Create( 
                    colorFrame.Width, 
                    colorFrame.Height, 
                    96, 
                    96, 
                    PixelFormats.Bgr32, 
                    null, 
                    colorPixels,
                    stride 
                );
                currentColorFrame = new Image<Bgr, Byte>( colorBmp.ToBitmap() );
                this.imgOutput.Source = ImageHelpers.ToBitmapSource( currentColorFrame ); 
            }
        }           
    }

辅助方法：

   public static System.Drawing.Bitmap ToBitmap(this BitmapSource bitmapsource)
    {
        System.Drawing.Bitmap bitmap;
        using ( var outStream = new MemoryStream() )
        {
            // from System.Media.BitmapImage to System.Drawing.Bitmap
            BitmapEncoder enc = new BmpBitmapEncoder();
            enc.Frames.Add( BitmapFrame.Create( bitmapsource ) );
            enc.Save( outStream );
            bitmap = new System.Drawing.Bitmap( outStream );
            return bitmap;
        }         
    }

    [DllImport("gdi32")]
    private static extern int DeleteObject(IntPtr o);
    /// <summary>
    /// Convert an IImage to a WPF BitmapSource. The result can be used in the Set Property of Image.Source
    /// </summary>
    /// <param name="image">The Emgu CV Image</param>
    /// <returns>The equivalent BitmapSource</returns>
    public static BitmapSource ToBitmapSource(IImage image)
    {
        using (System.Drawing.Bitmap source = image.Bitmap)
        {
            IntPtr ptr = source.GetHbitmap(); //obtain the Hbitmap
            BitmapSource bs = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
                ptr,
                IntPtr.Zero,
                Int32Rect.Empty,
                System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
            DeleteObject(ptr); //release the HBitmap
            return bs;
        }
    }

请尽快指出我的错误或给我任何建议。