Well, Ian McDiarmid has said that the "normal-looking" Senator/Chancellor Palpatine was a false face, and that he dropped the "mask" at the end of ROTS to reveal his true form. This is a McDiarmid quote from the Star Wars Insider magazine (issue #82):
"George once said a really useful thing when I began playing Palpatine (in Star Wars: Episode I The Phantom Menace), and I don't know if he remembers this. He said, "In a sense, your eyes are contact lenses." In other words, the Palpatine character was the most artificial-it was as if they had grafted his face and put in (his) eyes. Because the real Palpatine is the one who bursts forth at a calculated moment in Episode III just after persuading Anakin to kill Mace (Windu). That is when the true person comes out, letting the evil fully manifest itself. The Emperor that you see in the last film looks the way he does because he's very old and very evil-it is what he always looked like. He just had this carapace of looking like a fairly ordinary looking guy, a politician that smiled a bit, and so on."
But Lucas has never addressed this specifically (to my knowledge) in an interview or director's commentary track, so it's truly one of those things that is completely up to personal interpretation.
I just want to know how his robes changed in mid scene.
I never would've thought that sucking "life force" could even generate a whole new outfit (complete with red lining) out of thin air. The Force is a truly wondrous thing.
So true. And the really sad part is that the LFL story group was developed in large part for the very specific purpose of keeping *one* consistent continuity. Epic fail there. They are truly useless.
