In the movie Blade Runner, Director Ridley Scott and DP Jordan Cronenweth created a visual cinema gem to tell a film noir style story in a bleak futuristic setting. The use of low-key lighting, interesting shapes and patterns of light, and different color temperatures help to visually tell this story not only in a cinematic way, but one that is also consistent with the themes of the story.
One example of the use of color temperature is during the scenes at Tyrell's penthouse. The futuristic world of Los Angeles in the film is bleak, dark, and dirty, but the scenes at Tyrell's house are still low-key, but full of warm orange light contrasted with the blue and white lights of the rest of the world. This along with camera movements that always have the characters moving upward to get to Tyrell imply he is like a god on a high mountain, a creator of this future world who stands apart and away from it.
Another visually arresting element is the use of patterns and shapes of light in the film. During the scenes in Deckard's (Harrison Ford) apartment with him and Rachel (Sean Young) patterns of light and shadows are made from bright backlights shining through blinds or frames with blind patterns. This adds an interesting dynamic element to the scene and also helps to maintain the film noir feel. These types of lighting arrangements are used throughout the film.
Another example are the scenes inside the lobby of J.F. Sebastian's (William Sanderson) building. Everything is very dark except for bars of bright white/blue light that enter from holes in the roof and walls and move around as the lights move outside. This is used during the final climactic fight scene between Deckard and Roy (Rutger Hauer) as well. The use of this low-key lighting arrangment helps to make the environment more visually interesting and helps to create a sense of depth and space in the flat 2D film plane.