"His brother John, working at the movie visual effects company Industrial Light & Magic" is underselling John Knoll a bit - he became one of the more prominent figures there and won two Oscars for his work (and was nominated for more).

Taking his contribution for Photoshop into account, one could say that if you saw mainstream motion or still pictures in the Western world in the last three decades, you'll probably saw something influenced by him in one way or another.