External object files such as ActiveX DLLs and .NET assemblies typically return references to objects in their memory space. I'm pretty sure (in 90% of cases I've see) that your .NET assembly is also returning a reference to an image stored in its own memory space. Typically, in such cases, the dll contains methods to return the actual data of the image and these methods document how the data is returned. I would suggested looking for such a method for that .NET assembly.
If the .NET assembly actually returned the image data, you will need to know how it was constructed, then convert it to a 2D array of pixel values that can be converted to a picture format by the picture VIs in LabVIEW.
Hope this Helps.
Regards,
Jack J.
Applications Engineer
National Instruments