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.
It was exciting to set up... really brings you back to high school pyhsics.
Also note mention of hysteresis and Floyd-Steinberg Dithering which are worth reading up on.