Hertzfeld's tactic is nice, too: request a royalty for the unbundled version that Apple "would never do" -- but did.
Wow, this guy made 150k while he was about to make 750k from the Thunderscan stuff? Incredible stories.
Also note mention of hysteresis and Floyd-Steinberg Dithering which are worth reading up on.
It was exciting to set up... really brings you back to high school pyhsics.