BitmapPalette Class

            int width = 128;
            int height = width;
            int stride = width/8;
            byte[] pixels = new byte[height*stride];

            // Try creating a new image with a custom palette.
            List<System.Windows.Media.Color> colors = new List<System.Windows.Media.Color>();
            colors.Add(System.Windows.Media.Colors.Red);
            colors.Add(System.Windows.Media.Colors.Blue);
            colors.Add(System.Windows.Media.Colors.Green);
            BitmapPalette myPalette = new BitmapPalette(colors);

            // Creates a new empty image with the pre-defined palette

            BitmapSource image = BitmapSource.Create(
                width,
                height,
                96,
                96,
                PixelFormats.Indexed1,
                myPalette, 
                pixels, 
                stride);

            FileStream stream = new FileStream("empty.tif", FileMode.Create);
            TiffBitmapEncoder encoder = new TiffBitmapEncoder();
            TextBlock myTextBlock = new TextBlock();
            myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author.ToString();
            encoder.Frames.Add(BitmapFrame.Create(image));
            MessageBox.Show(myPalette.Colors.Count.ToString());
            encoder.Save(stream);

// Get the palette from an image
BitmapImage image2 = new BitmapImage();
image2.BeginInit();
image2.UriSource = new Uri("tulipfarm.tif", UriKind.RelativeOrAbsolute);
image2.EndInit();
BitmapPalette myPalette3 = new BitmapPalette(image2, 256);

//Draw the third Image
Image myImage2 = new Image();
myImage2.Source = image2;
myImage2.Stretch = Stretch.None;
myImage2.Margin = new Thickness(20);