I came across a recent post on IMDB by the writer who will be doing the novelization for the movie. Interestingly enough, she said:
As I understand it, it's based on an obscure British comic. I tried to get my hands on a copy, but failed.
While looking up that quote, I came across another thread where it seems no one could actually figure out whether it was based on a comic or not.
I also found an old comment (the 3rd post in this thread) in March 2004 on the Milla Jovovich forum where a fan said:
I don't know much about Ultraviolet the character other than she's a comic book hero.
Although I know what I think, I'd like to cut the hypothesizing and get the facts straight...