Color-scanning grating-based backlighting includes a color scanning protocol to provide different colors of light in different regions of a plate light guide with an intervening dark region. A color-scanning grating-based backlight includes the plate light guide and a diffraction grating configured to diffractively couple out a portion of a guided light beam as a coupled-out light beam directed away from a plate light guide surface at a predetermined principal angular direction. The backlight further includes a multicolor light source configured to provide the different colors of light to the plate light guide as the guided light beam according to the color scanning protocol. Provided light of a first color in a first region is separated from provided light of a second color in a second region one or both by the intervening dark region and by a light-confining wall of the plate light guide.