Retrieving high precision data from GPU

[Goose]

I am writing an app that send data (in the form of textures) to the GPU for processing. I then retrieve the results using

Surface renderTarget = device.GetRenderTarget(0);
GraphicsStream stream = SurfaceLoader.SaveToStream(ImageFileFormat.Bmp,renderTarget);
Bitmap bmp = (Bitmap)Bitmap.FromStream(stream);

 

The problem is that no matter what precision I set my render target too (A8R8G8B8 or A32R32G32B32), the result always comes out as a 32Bpp image (A8R8G8B8). Is there any way to get full the full 32bit precision per value out? Thanks