dk.simongray.colour-coded.gamut — dk.simongray/colour-coded 0.1.0

Whether a colour lies in the gamut of a space, and the nearest colour that does.

There are three ways to bring a colour into a gamut:

• to-gamut, the gamut mapping of CSS Color 4, lowers its chroma in OKLCH at the same lightness and hue
• clip clamps each channel, which shifts the lightness and the hue a little, but is what browsers still do (csswg-drafts issue 9449)
• reduce-chroma lowers its chroma in a polar space of your choice, e.g. LCH, and keeps that space's lightness and hue exactly

https://www.w3.org/TR/css-color-4/#gamut-mapping

clip clj/s

(clip x)

(clip x space)

The colour x in the space, by default sRGB, with each channel clamped to its range. Browsers show a colour outside the display's gamut this way today. HSL and HWB clamp in sRGB, and an unbounded space, e.g. Oklab, doesn't clamp.

epsilon clj/s

How far outside its range a channel may lie and still count as inside it. Colour.js allows the same.

in-gamut? clj/s

(in-gamut? x)

(in-gamut? x space)

Whether the colour x lies in the gamut of the space, by default sRGB. Every colour lies in the gamut of an unbounded space, e.g. Oklab.

reduce-chroma clj/s

(reduce-chroma x space)

(reduce-chroma x space gamut-space)

The colour x in the polar space, e.g. :lch or :oklch, with its chroma lowered until it lies in the gamut of gamut-space, by default sRGB, keeping its lightness and hue in that space exactly.

to-gamut clj/s

(to-gamut x)

(to-gamut x space)

The colour x in the gamut of the space, by default sRGB, at the same OKLCH lightness and hue, by the gamut mapping of CSS Color 4: a binary search on its chroma, which takes the clipped colour once it's within a ΔEOK of 0.02.