Wpf - Get Image From Resource Dll As MemoryStream?

I use WPF and my program has images in a DLL resource file. I have this well working way to read in images from disk:

Private Function GetImageFromFile(ByVal fileName As String) As BitmapImage
Dim buffer As Byte() = IO.File.ReadAllBytes(fileName)
Dim memoryStream As New IO.MemoryStream(buffer)

[Code]....

Now, how can I get images in this MemoryStream-way from a DLL resource?

The basic problem: If I use simply the "bitmap.UriSource = whatever uri" way and load many images in sequence like an animation it builds up the memory. I tried with the above memorystream way and it worked perfectly fine, but then I store my images in a dll and I don't know how to do this trick. If anybody knows how to read many images from a managed dll without building up the memory