Part of Family 6 (Colour & effects) — squeezing more colour out of the PPU. The SNES shows 256 colours at once from a 15-bit (32768-colour) palette — unless you cheat. This family is the colour-math blend, the palette-bypass mode, and the tricks that push past 256 by reloading the palette mid-frame.

The ladder

Rung	Example	Developer question
6b	palette_cycle	How do I animate (waterfall/fire/lights) by rotating CGRAM, no pixels moved?
6c.1	transparency	How do I blend two layers with colour math?
6c.2	shadow_tint	How do I darken (night) or colour-cast (underwater/sunset) a whole scene?
6c.3	direct_color	How do I use direct-colour mode (the pixel byte is the RGB)?
6d.1	gradient_9bit	How do I fake a "9-bit" gradient with brightness dithering?
6d.2	hicolor_1792	How do I show 1792 colours via H-IRQ CGRAM streaming?
6d.3	hicolor_blend	How do I show 3840 colours via an RGB channel-split blend?

The idea in one screen

The PPU reads pixel colours from CGRAM (256 slots). Colour math ($2130– $2132) adds or subtracts one layer's colour over another — transparency, shadows, tints. Direct colour spends the 8bpp pixel byte as a BGR value, skipping CGRAM entirely. And to beat the 256-at-once limit, you reload CGRAM mid-frame under an H-IRQ so different scanlines see different palettes (hicolor_1792), or split the RGB channels across two blended layers (hicolor_blend, 3840 colours).

direct_color — the pixel byte IS the color "9-bit" gradient — brightness-dithered backdrop HiColor — 1792 colors from a 4bpp background "3840 colors" — RGB channel-split blend palette_cycle — animate by rotating CGRAM shadow_tint — recolour a whole scene at once Color Addition Transparency