Ah, I see. I'm still pretty new to this so I wasn't sure if the larger texture files were comprised of many layers that made for things like bump and illuminosity  and by just saving the thumb to disk I was missing out on the lower layers.

I guess rethinking it you only need what you can visually see in the texture and in the instance of bump the 3D software, itself, calculates shade opacities for dents and cavities. 

But that's how newby I am. =D

You'd probably like Mod Tools texture painting setup because it still requires heavy dependency on inputting, organizing and aligning texture files.

I can't quite say yet rather I like it that way or the easy peasy way through a 3D paint specific program other than that there appears to be a whole lot more control over practically everything when it comes to old-fashioned texture mapping.

Ah, and mustn't forget the fact that you can go back to any texture layer and tweak at any time where as its all ctrl Z as far as the eye can see with something like Sculptris's paint setup.