It seems that both William Gibson and Ridley Scott were, at the time, both very much influenced by much of the visual styles and artwork featured in the magazine "Heavy Metal", notably the work by French artist Jean Giraud, AKA "Moebius". One story in particular, called "The Long Tomorrow", written by Dan O'Bannon and drawn by Moebius, was a major influence on the visual design of BR. Ironically, this story was in fact a parody of early American Film Noir.

Gibson, in an interview by Lance Loud in an article on the 10th anniversary of "Blade Runner" for the magazine "Details" (October 1992 issue), had the following to say:

"About ten minutes into Blade Runner, I reeled out of the theater in complete despair over its visual brilliance and its similarity to the "look" of Neuromancer, my [then] largely unwritten first novel. Not only had I been beaten to the semiotic punch, but this damned movie looked better than the images in my head! With time, as I got over that, I started to take a certain delight in the way the film began to affect the way the world looked. Club fashions, at first, then rock videos, finally even architecture. Amazing! A science fiction movie affecting reality!"

"Years later, I was having lunch with Ridley, and when the conversation turned to inspiration, we were both very clear about our debt to the Metal Hurlant [the original Heavy Metal magazine] school of the '70s--Moebius and the others. But it was also obvious that Scott understood the importance of information density to perceptual overload. When Blade Runner works best, it induces a lyrical sort of information sickness, that quintessentially postmodern cocktail of ecstasy and dread. It was what cyberpunk was supposed to be all about."

William Gibson

Also, here is an excerpt from an introduction Gibson wrote for the graphic novel adaptation of his own "Neuromancer" book:

"So it's entirely fair to say, and I've said it before, that the way Neuromancer-the-novel "looks" was influenced in large part by some of the artwork I saw in 'Heavy Metal'. I assume that this must also be true of John Carpenter's 'Escape from New York', Ridley Scott's 'Blade Runner'", and all other artefacts of the style sometimes dubbed 'cyberpunk'. Those French guys, they got their end in early."