HOW TO: Get RasterImage from UWP SoftwareBitmap

      public async Task<RasterImage> RasterImageFromSoftwareBitmap(SoftwareBitmap softwareBitmap)
      {
         byte[] array = null;

         using (var ms = new InMemoryRandomAccessStream())
         {
            BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, ms);
            encoder.SetSoftwareBitmap(softwareBitmap);
            await encoder.FlushAsync();

            array = new byte[ms.Size];
            await ms.ReadAsync(array.AsBuffer(), (uint)ms.Size, InputStreamOptions.None);
            using (RasterCodecs codecs = new RasterCodecs())
            {
               var s = ms.AsStream();
               s.Position = 0;
               RasterImage img = codecs.Load(s);
               return img;
            }
         }
      }