In the early days of Macintosh, Bill Atkinson (of HyperCard, QuickDraw, MacPaint & nature photography fame) developed a very elegant dithering filter to convert greyscale image data to the 1 bit black & white Mac video display. The dithering produced by this routine was much higher quality than the now-a-days ubiquitous Floyd-Steinberg or “Error-diffusion” filter (used by QuickTime, PhotoShop).
HyperDither is an OS X image processing utility that converts color or grayscale images to 1 bit black & white using a sophisticated dithering routine. Specifically, HyperDither implements the Atkinson dithering filter. The autor of HyperDither emailed Bill Atkinson in January, 2003 and inquire about the details of the algorithm; Bill was kind enough to respond with a brief write up of the routine—15 minutes later it was up and running.
Retro is in. Mahalo to Scott for the pointer!