You should be able to use BitmapSource.Create just fine passing the byte array:

byte[] pixels = memoryStream.ToArray();

BitmapSource bmp = BitmapSource.Create(pixelWidth, pixelHeight, 96.0, 96.0, pixels, pixelWidth * 3, BitmapSource.Format.RGB8);

Are you getting any error with this approach?

Tried it but doesn't work.

I don't know the pixels width.Height so i used:

Bitmap b = new Bitmap(File.ContentStream);
ImageSource Is = BitmapSource.Create(b.Width, b.Height, b.HorizontalResolution, b.VerticalResolution, File.Content,b.Width 3, BitmapSource.Format.RGB8);
80 80 96 96 byte[2162] 80 3
Source:
http://i64.tinypic.com/14in0np.png

Result:
http://i68.tinypic.com/24nis5v.png

The file is an .jpg file.
When i write it to disk and hit properties is lists with an Bitdepth of 24

I am not sure this is the best approach. If you already have the images in a database I think the best way is installing a TextureProvider that will allow you to return a Stream for each requested URI.

I Already use a custom texture provider for loading images from filesystem, wich indeed needs an uri and spills out an stream.
But problem is i cannot acces the files in the database by Uri.
When i open the database, the images are loaded into the ram, and in the c# object i can only get a stream or a byte[].

I think this is not a bug and it is better to discuss it in the forums, because it can help others in the same situation, could you please create a post there?