Drawing Libraries

var targetFormat = PixelFormat.Format8bppIndexed; // feel free to try other formats as well
using (Bitmap bmpSrc = Icons.Shield.ExtractBitmap(new Size(256, 256)))
using (Bitmap bmpDst = new Bitmap(256, 256, targetFormat))
{
    using (IReadableBitmapData dataSrc = bmpSrc.GetReadableBitmapData())
    using (IWritableBitmapData dataDst = bmpDst.GetWritableBitmapData())
    {
        IReadableBitmapDataRow rowSrc = dataSrc.FirstRow;
        IWritableBitmapDataRow rowDst = dataDst.FirstRow;
        do
        {
            for (int x = 0; x < dataSrc.Width; x++)
                rowDst[x] = rowSrc[x]; // works also between different pixel formats

        } while (rowSrc.MoveNextRow() && rowDst.MoveNextRow());
    }

    bmpSrc.SaveAsPng(@"c:\temp\bmpSrc.png");
    bmpDst.SaveAsPng(@"c:\temp\bmpDst.png"); // or saveAsGif/SaveAsTiff to preserve the indexed format
}

💡 Tip: See more examples with images at the GetReadWriteBitmapData extension method.

If you know the actual pixel format you can also access the raw data in a managed way. See the IReadableBitmapDataRow.ReadRaw and IWritableBitmapDataRow.WriteRaw methods for details and examples.