It’s very noticeable that the world of The Matrix is tinted green whereas scenes outside The Matrix have a much more realistic tone.
Why was a green filter chosen to portray the world of The Matrix?
.. Wachowskis: One of the things we tried to do with the Neb for when we were shooting “in the real world” was use long lenses to separate the humans from the backgrounds as opposed to when we shot the Matrix we used short lenses to place the humans in specific deep spaces. We also tinted all of the lights blue in the “real world” and green in the Matrix.
… Spark: What made you decide on the green tint for being in the Matrix?
Wachowskis: It was a whole motif inspired by the phosphorous green of old PC’s.
.. BILL: To distinguish the Matrix from ‘reality’, from the Nebuchadnezzar and the pods, ‘reality’ was given a cooler look, a bluer, more normal, less sickly look. The future in the film is cold, the sun is blotted out, there is no real warmth unless it is artificial heat, so that is whey they went for the cool side. Whereas the Matrix, created by the computers, is a decadent, decaying world, so it has a green hue. These are the two different colors – green and blue. The Matrix should make you feel sick, and in ‘reality’ you should feel a little more at home, but never comfortable. If you make it gold and warm you know that it is home, a safe haven. The other day I started using warm lights, I did this unconsciously for the first time in Neo’s bedroom. It just felt right that it should be slightly warm. As harsh as that bunk is, it is the only home he has got.