Random CIELAB Color Generator

Generate a CIELAB D50 tuple with lightness in [0, 100) and a/b axes in [-128, 128) using injected randomness; the tuple is not clipped to a device gamut.

Description

Sample CIELAB D50 lightness and signed a/b coordinates within fixed independent ranges.

CIELAB separates lightness from the signed a and b color-opponent axes. CSS lab() uses the D50 reference white, distinguishing this representation from raw RGB channels.^[1]

The output lightness ranges from zero toward 100; a and b each range from −128 toward 128. This is a sampling box rather than the set of displayable sRGB colors.

When to use Random CIELAB Color Generator

Use it for CIE color-coordinate fixtures or studies where out-of-gamut coordinates are permitted.

How to use Random CIELAB Color Generator and understand its results

Run without input fields, using {} programmatically.
Read lightness on the 0–100 scale and preserve the signed a and b coordinates.
Format the example as CSS lab(25% -64 -64), or convert under the intended white-point and gamut convention before displaying it.

lightness = 100 × r1; a = −128 + 256 × r2; b = −128 + 256 × r3

Three finite draws in [0, 1) independently select the coordinates.

The implementation returns numbers directly without converting from RGB, clipping to gamut, performing chromatic adaptation, or generating a CSS string. Coordinate-uniform sampling is not uniform over displayable colors.

json

{
  "input": {},
  "randomDraw": 0.25,
  "output": {
    "lightness": 25,
    "a": -64,
    "b": -64
  }
}

Lightness zero and negative a/b endpoints are permitted. Positive upper bounds are approached but not intentionally included.

Floating-point rounding applies near endpoints. An invalid draw in any coordinate fails instead of being clamped.

Limitations and assumptions

The default source is Math.random; no seed input or cryptographic entropy guarantee is provided. Repeated runs may select the same result, and the distribution depends on the random source.

There is no device-gamut, accessibility, perceptual-spacing, printing, or palette-harmony guarantee. Lightness alone does not determine foreground/background contrast.

CIELAB is not OKLab; their coordinate scales and color-space definitions differ.

Alternative or Complementary methods

Choose the companion coordinate representation when needed, observing its conversion formulas. RGB generation provides directly bounded byte channels for another fixture convention.

References

CSS Color Module Level 4 — World Wide Web Consortium

Similar or alternative tools

Random CIELCH Color Generator
Sample the companion CIE representation under D50.
Random RGB Color Generator
Generate three integer sRGB byte channels.