A specifier book like Pantone or Munsell samples colour space unevenly — densely where its trade cares, thinly elsewhere — because it is a record of what people actually made. The Dictionary needs the opposite: a frame in which equal distance is equal perceived difference, filled evenly, so that "how far is this shade from that one" has a single honest answer. That frame is the fine grid.
What it is
Take OKLab — the perceptual colour space the colour list already uses — and simply fill it at one spacing in every direction:
- a lightness level every 0.025 from black to white (41 levels);
- on each level, a chroma ring every 0.025 outward from the grey at the centre;
- round each ring, points at an arc spacing of ~0.025, so outer rings carry more hues.
That spacing is two to three just-noticeable differences: close enough that nothing finer would be visible on cloth, far enough that no two grid colours look the same side by side. The result is about 5,100 colours — Pantone scale, but evenly spread rather than editorially chosen.
Clipped to what cloth can actually be
A screen can show colours no dye can reach, so the grid is not filled out to the sRGB edge but to the dyeable boundary — one grid step beyond the real-surface gamut measured by Pointer in 1980, with the black and white caps added. Four limits were drawn and compared on the way:
| boundary | what it is | colours |
|---|---|---|
| sRGB | what a screen shows | 3,489 |
| real-surface (Pointer) | measured physical dyes & pigments | 4,231 |
| fine grid (dyeable) | the Dictionary's working gamut | ~5,100 |
| optimal (MacAdam) | the theoretical reflectance limit | 9,337 |
So real dyeable colour is roughly a tenth of the visible cone — and the fine grid sits just inside the measured edge of it.
Naming a colour
Every fine-grid colour is a lattice point, so its name is its coordinates: level-ring-hue,
three numbers — level (0 black cap → 40 white cap), ring (the chroma step out from grey), and the
dot's index round its ring. The greys are level-00. Any dye anyone quotes, from any supplier's
card, sits within one step of exactly one code — which is what makes the grid a common frame for
comparing palettes that were never designed to line up.
The full genesis — why 0.025, why a cylinder and not a cube, the colorimetry behind the four limits — is in the project's research notes; this is the short version. The fine grid is the substrate the six-colour reference palette is anchored to.