Playing with dithering and hue using 3x3 stamps. Stamping 19k is slow (even slower on turbowarp !) but data compression is reasonably good in Hue, Saturation, Luminesce (HSL) format. If brightness is sampled at 3x3 then Hue can be down sampled to 9x9, without noticeable color bleed.
npr render stamping 19200 3x3 tiles with a 3x3 ordered dither with 9x9 chroma subsampling Reasonable details for 8kb data vs 240kb for grayscale encoded RLE 480x360 o3x3 dither values (477/9)x(360/9)= 2,120 Hue values (1...180) (480/3)x(360/3)= 19,120 Tile Dither/Luminesce values (-128...128) Frequency analysis: 18026 tiles out of 19200 are just 8 tiles for 3x3 ordered dither pattern For Hue frequency, 2120 values there are 126 unique colors with the first 64 colors contain majority, 1937 hue values. Saturation is one value per frame.