The article references "The Amiga digitizer" but what it describes (a monochrome video camera + color filter wheel) fits the Digi-View digitizer, an Amiga peripheral made by NewTek.

Since the first HAM game, Pioneer Plague, didn't exist until 1988, and Thexder had 256-colour graphics on MCGA in 1987. I'd argue that the amiga did not birth 256-colour gaming.