Do you know what, I remember that because I purposely bought the remastered one because the original version was horrid.As a 2002 production, Gangs of New York was made during the early days of the transition to the Digital Intermediate process, and I believe managed to avoid using one. At least, I don't think it had a full end-to-end DI, though it may have had a partial DI for VFX shots or scenes with digital background plates.
Gangs of New York has already had a couple Blu-ray editions. The first one had an atrocious transfer with tons of DNR and edge enhancement. Fortunately, it was remastered later in 2010 with a much better-looking disc.