# Colors The 20 definitions of the colors library, each with its Epsil spelling, its MathJSON name, its signature and its full description. Each definition is listed under its Epsil spelling (the MathJSON name when it has none), with its signature in the engine's type syntax. The [Standard Library](/library/) page is the one-page index of every category. ## Definitions ### asHsl MathJSON `AsHsl` · `(color | string | tuple) -> color` Convert any color to HSL (hue degrees, s/l 0-1) ### asHsv MathJSON `AsHsv` · `(color | string | tuple) -> color` Convert any color to HSV (hue degrees, s/v 0-1) ### asOklab MathJSON `AsOklab` · `(color | string | tuple) -> color` Convert any color to OKLab ### asOklch MathJSON `AsOklch` · `(color | string | tuple) -> color` Convert any color to OKLCh ### asRgb MathJSON `AsRgb` · `(color | string | tuple) -> color` Convert any color to sRGB (channels 0-1) ### color MathJSON `Color` · `(string) -> color` Parse a CSS-style color string to an Oklch color ### colorContrast MathJSON `ColorContrast` · `(color | string | tuple, color | string | tuple) -> number` APCA contrast ratio between two colors ### colorDelta MathJSON `ColorDelta` · `(color | string | tuple, color | string | tuple) -> number` Perceptual color difference (ΔE_OK) between two colors ### colorFromColorspace MathJSON `ColorFromColorspace` · `(color | tuple, string) -> color` Build a color from channel values in a named color space. The result is a color on every route — the color head of the named space when evaluated, the target's color value when compiled. To read the channels back out, call ColorToColorspace(color, space) ### colorMix MathJSON `ColorMix` · `(color | string | tuple, color | string | tuple, number?) -> color` Mix two colors in OKLCh space ### colorToColorspace MathJSON `ColorToColorspace` · `(color | string | tuple, string) -> tuple` Convert a color to components in a target color space ### colorToString MathJSON `ColorToString` · `(color | string | tuple, string?) -> string` Convert a color to a string in the specified format: "hex" (the default), "rgb", "hsl", "oklch", "srgb" (the same as "hex") or "display-p3" (the CSS spelling `color(display-p3 r g b)`). The hex, rgb, hsl and srgb formats map the color into the sRGB gamut, and display-p3 maps it into the Display-P3 gamut, with the CSS Color 4 gamut mapping: the OKLCh chroma is reduced at constant lightness and hue. The channels are not clipped one by one. The oklch format has no gamut and is not mapped ### colormap MathJSON `Colormap` · `(string, number?) -> color | list` Sample colors from a named palette ### contrastingColor MathJSON `ContrastingColor` · `(color | string | tuple, (color | string | tuple)?, (color | string | tuple)?) -> color` Choose the foreground color with better APCA contrast against a background, answered as given: the interpreter keeps the color head the candidate was written with, and a compiled target answers the same color in its canonical form ### gamutMap MathJSON `GamutMap` · `(color | string | tuple, string?) -> color` Map a color into a target gamut, "srgb" (the default) or "display-p3", with the CSS Color 4 gamut-mapping algorithm: the OKLCh chroma is reduced, at constant lightness and hue, until the color is inside the gamut or until clipping each channel changes the color by less than a just noticeable difference (ΔE_OK 0.02). A lightness of 1 or more gives white, and 0 or less gives black. A color already inside the gamut is returned unchanged. The result is an Rgb color, in sRGB coordinates also for "display-p3": its channels are in [0, 1] for "srgb", and for "display-p3" they can be outside [0, 1] (extended sRGB) for a color that is inside the Display-P3 gamut but outside the sRGB gamut. Color values themselves have no gamut: only this operator and the string output map a color ### hsl MathJSON `Hsl` · `(number, number, number, number?) -> color` HSL color (hue degrees, saturation/lightness 0-1, optional alpha) ### hsv MathJSON `Hsv` · `(number, number, number, number?) -> color` HSV color (hue degrees, saturation/value 0-1, optional alpha) ### oklab MathJSON `Oklab` · `(number, number, number, number?) -> color` OKLab color (L 0-1, a/b ~ -0.4..0.4, optional alpha) ### oklch MathJSON `Oklch` · `(number, number, number, number?) -> color` OKLCh color (L 0-1, C 0-~0.4, hue degrees, optional alpha) ### rgb MathJSON `Rgb` · `(number, number, number, number?) -> color` sRGB color (channels 0-1, optional alpha 0-1)