HOWTO: Create Palette Optimized for Several Bitmaps

public class CommonPaletteCreator
{
	Aurigma.GraphicsMill.Bitmap[] bitmaps = null;

	public CommonPaletteCreator()
	{

	}

	//Import RtlMoveMemory function for copying memory in unmanaged heap
	[DllImport("kernel32", EntryPoint="RtlMoveMemory")]
	private static extern int CopyMemory(IntPtr lpvDest, IntPtr lpvSrc, int cbCopy);

	public Aurigma.GraphicsMill.Bitmap[] Bitmaps
	{
		set
		{
			bitmaps = value;
		}
		get
		{
			return bitmaps;
		}
	}

	public Aurigma.GraphicsMill.ColorPalette CreatePalette()
	{			
		//All source bitmaps should have the same pixel format
		Aurigma.GraphicsMill.PixelFormat commonPixelFormat =
			Aurigma.GraphicsMill.PixelFormat.Format24bppRgb; //Aurigma.GraphicsMill.PixelFormat.Format32bppArgb

		//Total pixel count in all bitmaps
		int totalPixelCount = 0;
		foreach (Aurigma.GraphicsMill.Bitmap bitmap in bitmaps)
		{
			if (bitmap.PixelFormat != commonPixelFormat)
			{
				//instead of exception throwing, we can also convert bitmap to required pixel format
				throw new Exception("Only 24 bpp pixel format is supported.");
			}
			totalPixelCount += bitmap.Width * bitmap.Height;
		}
			
		//Create common bitmap with width equals totalPixelCount and height equals 1
		using (Aurigma.GraphicsMill.Bitmap commonBitmap = new Aurigma.GraphicsMill.Bitmap(totalPixelCount, 1, commonPixelFormat))
		{
			int bytesPerPixel = commonBitmap.BitsPerPixel / 8;
	
			Aurigma.GraphicsMill.BitmapData commonBitmapData = commonBitmap.LockBits();

			//Get pointer in unmanaged heap for common bitmap raw data
			IntPtr commonBitmapPtr = commonBitmapData.Scan0;

			//Copy data of source images to common image
			foreach (Aurigma.GraphicsMill.Bitmap bitmap in bitmaps)
			{
				Aurigma.GraphicsMill.BitmapData bitmapData = bitmap.LockBits();

				//Get pointer in unmanaged heap for bitmap raw data
				IntPtr bitmapPtr = bitmapData.Scan0;

				//Copy raw data from bitmap to common bitmap
				for (int i = 0; i < bitmap.Height ; i++)
				{
					//Data actaully are not marshalled here, as we work in unmanaged heap only
					CopyMemory(commonBitmapPtr, bitmapPtr, 
						bitmapData.Width * bytesPerPixel);

					//Pointer incrementing
					bitmapPtr = (IntPtr)((int)(bitmapPtr) + bitmapData.Stride);
					commonBitmapPtr = (IntPtr)((int)(commonBitmapPtr) + bitmapData.Width * bytesPerPixel);
				}

				bitmap.UnlockBits(bitmapData);
			}

			commonBitmap.UnlockBits(commonBitmapData);

			//Create common palette
			return new Aurigma.GraphicsMill.ColorPalette(commonBitmap, false);
		}
	}
}

class CommonPaletteTest
{
	/// 

	/// The main entry point for the application.
	/// 
	[STAThread]
	static void Main(string[] args)
	{
		//Load images
		Aurigma.GraphicsMill.Bitmap bitmap1 =
			new Aurigma.GraphicsMill.Bitmap(@"C:\Flower.jpg");
		Aurigma.GraphicsMill.Bitmap bitmap2 =
			new Aurigma.GraphicsMill.Bitmap(@"C:\Mountain.jpg");
		Aurigma.GraphicsMill.Bitmap bitmap3 =
			new Aurigma.GraphicsMill.Bitmap(@"C:\Parrot.jpg");
	
		//Create common palette creator
		CommonPaletteCreator paletteCreator = new CommonPaletteCreator();
		
		//Set bitmaps for which we need to create common palette
		paletteCreator.Bitmaps = new Aurigma.GraphicsMill.Bitmap[]{bitmap1, bitmap2, bitmap3};

		//Create common palette
		Aurigma.GraphicsMill.ColorPalette commonPalette = paletteCreator.CreatePalette();

		//Reduce colors using common palette
		bitmap1.ColorManagement.ConvertToIndexed(8, Aurigma.GraphicsMill.ColorPaletteType.Custom,
			commonPalette);
		bitmap2.ColorManagement.ConvertToIndexed(8, Aurigma.GraphicsMill.ColorPaletteType.Custom,
			commonPalette);
		bitmap3.ColorManagement.ConvertToIndexed(8, Aurigma.GraphicsMill.ColorPaletteType.Custom,
			commonPalette);

		//Save results
		bitmap1.Save(@"C:\Flower.png");
		bitmap2.Save(@"C:\Mountain.png");
		bitmap3.Save(@"C:\Parrot.png");
	}
}