I always got superimposed red and blue, like an anaglyph image, or something in the base RGB spectrum of light (typically red-blue or red-green). Partially because of the "digitized" themes that pervade a lot of Kid A songs. Partially because I listened to In Rainbows before Kid A, and the song hearkened mentally to Videotape for some reason. And partially because the songs on Kid A just sound like the artificial luminescence of digital information, broken into its base sonic/visual components.