Asking this for someone who to my knowledge doesn't use StackExchange... ~20 years ago (so this must be older than that), he mentioned having seen some SF TV show or movie with a "reverse universe" with black stars on white. I recall that back then, he thought it was from somewhere in Star Trek, but I've seen most Star Trek material made up to that time and read the Star Trek Encyclopedia, and I'm pretty confident that's not it.
I'd like to offer an alternative: The Star Trek Animated show titled 'The Counter-Clock Incident'. To my recollection, when the Enterprise goes through a 'warp' to a universe where time flows in reverse, space is portrayed as white, with all the stars as points of black.
My guess is you're looking for the Star Trek episode "The Alternative Factor", from series 1, episode #27.
Anti-Lazarus calmly admits to stealing the Enterprise's dilithium. He informs Kirk that his people thought that two universes exist in which attempts to prove it, caused their destruction. Anti-Lazarus tells Kirk that only one Lazarus can exist in one universe simultaneously. Lazarus's time traveling ship is the "dimensional door," and connects both Anti-Lazarus and Lazarus; only by destroying the ship with the two Lazarus inside "dimensional corridor" which links the universes can both universes be saved.
Kirk confronts Lazarus, and pushes him into the "dimensional door." Kirk heads back to the Enterprise, ordering the ship's phasers to target the dimension ship. The two Lazaruses meet once more and fight as phaser beams vaporize the ship, sealing the two for all of eternity, caught together between universes.
It is in the "dimensional corridor" that the reverse imaging occurs.
I see that @NKCampbell has found the same episode ... so 2 people at the same time :)
I support "The Counter-Clock Incident".
Another possibility is the first episode of The Outer Limits, in which a being transported from the Andromeda Galaxy was depicted by using negative film of his scenes.
I believe some Cthulhu Mythos stories mentioning a world in outer space with black stars in a white sky - easier written than scientifically justified. But I doubt there have been any films showing that.