CMYK Pdf with Transparency Converts to Pure White Png

using (var reader = ImageReader.Create(OriginalFilepath))

                using (var converter = new Aurigma.GraphicsMill.Transforms.ColorConverter(PixelFormat.Format24bppRgb))
                using (var writer = ImageWriter.Create(WorkingFilepath))
                {
                    // If no color profile is set
                    converter.DefaultSourceProfile = reader.ColorProfile;
                    if (reader.ColorProfile == null)
                        converter.DefaultSourceProfile = new ColorProfile(Configuration.ProfilesDirectory + "ISOcoated_v2_eci.icc");

                    if (reader.PixelFormat.IsRgb && reader.PixelFormat != PixelFormat.Format24bppRgb)
                    {
                        converter.BackgroundColor = RgbColor.White;

                        // Assign some default color profile
                        converter.DefaultSourceProfile = ColorProfile.FromSrgb();
                        converter.DestinationProfile = ColorProfile.FromSrgb();
                    }
                    if (reader.PixelFormat.IsCmyk)
                    {
                        converter.BackgroundColor = new CmykColor(0, 0, 0, 0, 100);

                        converter.ColorManagementEngine = ColorManagementEngine.LittleCms;
                        converter.DestinationProfile = ColorProfile.FromSrgb();
                    }

                    Pipeline.Run(reader + converter + writer);
                }
            }