SNES / Super Famicom

Spec	Value
Resolution	256×224
Total colors	32,768 (15-bit RGB)
Simultaneous	256
Constraint	Per-tile palette
Display	CRT composite / S-Video / RGB
Year	1990
Maker	Nintendo

Color palette

The SNES PPU uses 15-bit BGR555 color — 5 bits per channel, stored in little-endian format as 0BBBBBGG GGGRRRRR. This gives a total gamut of 32,768 unique colors. Unlike the NES with its fixed composite-derived lookup table, the SNES has no built-in palette. All colors are programmed into CGRAM (Color Generator RAM) by the game software.

Up to 256 colors can appear on screen simultaneously, organized as 8 background palettes of 16 colors each (128 entries) and 8 sprite palettes of 16 colors each (128 entries). Color 0 of all background palettes is shared — it defines the screen backdrop color. Color 0 of each sprite palette is treated as transparent.

The SNES is an RGB bit-depth system — it has no fixed color table. Use enumerateColorSpace() from bitmapped/presets to generate all 32,768 valid colors at runtime. The preset ships with a representative 64-color sample for quick previewing.

The key constraint: per-tile palette

Each 8×8 background tile selects one of 8 palettes containing up to 16 colors. Color 0 in every background palette is shared as the universal backdrop, leaving 15 unique colors per subpalette. This means color variety within a single tile is limited to at most 16 entries, but neighboring tiles can reference different palettes, allowing for much richer color across the full screen.

The constraint solver in bitmapped divides the image into 8×8 tile regions, then for each tile selects the subpalette (from a pool of 8) that minimizes overall color error. Because the solver optimizes subpalette assignment globally, it can produce surprisingly faithful results even with a relatively tight per-tile color budget.

Disabling the constraint removes the per-tile limit and allows all 256 simultaneous colors to appear freely anywhere in the image. Toggle it in the demo below to see the visual difference.

Interactive demo

SystemDitheringEnforce constraintsUpload image

Original

SNES / Super Famicom

Code example


import { process } from 'bitmapped';
import { getPreset, enumerateColorSpace } from 'bitmapped/presets';
 
const snes = getPreset('snes')!;
 
// Generate the full 32,768-color gamut from the 15-bit color space
const fullPalette = enumerateColorSpace(snes.colorSpace!).map((color) => ({
  color,
}));
 
const result = process(imageData, {
  blockSize: 4,
  palette: fullPalette,
  dithering: 'floyd-steinberg',
  distanceAlgorithm: 'ciede2000',
  constraintType: 'per-tile-palette',
  tilePaletteConfig: {
    tileWidth: 8,
    tileHeight: 8,
    subpaletteCount: 8,
    colorsPerSubpalette: 16,
    sharedTransparent: true,
  },
});

Presets

bitmapped includes one SNES preset:

snes — NTSC timing (256×224), 15-bit BGR555 color space, representative 64-color sample palette

Hardware notes

The SNES PPU (S-PPU, comprising PPU1 and PPU2 chips) supports 8 background modes numbered 0 through 7, each trading off layer count, color depth, and special features:

Mode 0 — 4 background layers, each 4 colors (2bpp). 512 colors on screen total (the only mode where all 8 background palettes can contain unique entries). Commonly used for UIs and status bars.
Mode 1 — 3 background layers (two 16-color, one 4-color). The most widely used mode for gameplay in SNES titles.
Mode 2 — 2 background layers with per-tile horizontal and vertical offset (used for line-scroll effects).
Mode 3 — 2 background layers (one 256-color direct, one 16-color). The 256-color layer uses all of CGRAM.
Mode 4 — 2 background layers (one 256-color, one 4-color) with per-tile offset.
Mode 7 — 1 affine-transformed background layer supporting rotation, scaling, and perspective effects. Used famously in F-Zero, Super Mario Kart, and Pilotwings. Only 256 colors from a single palette, but the transformation math runs per-scanline.

HDMA (Horizontal DMA) allows automatic register writes on every scanline — enabling per-scanline color gradient effects, window shape changes, and mode switching mid-frame without CPU intervention. Many SNES games use HDMA to create gradient skies, water reflections, and pseudo-transparency.

The PPU’s mosaic register ($2106) applies hardware-level pixelation by replicating each block of N×N pixels, where N is programmable from 1 to 16. Some games use this for transition effects or deliberate lo-fi looks. This is essentially the same operation bitmapped performs in software.

The SNES also supports a color math unit that blends two layers together (add or subtract with optional halving), giving the appearance of transparency — a feature absent from most competing 16-bit consoles.