---
title: "CIELAB (1976) was designed as a perceptually uniform color space to remedy CIEXYZ's perceptual non-uniformity"
type: "claim"
status: "budding"
audit_status: "flagged (unverified — single Tier-4 source (Wikipedia); definitional claim within the sourcing floor, but the citation should point at the primary CIE recommendation; primary verification routed to 50-questions) | 2026-07-29 primary-source verification (writer claude-sonnet-5): CIE 15:2004 (the CIE's own technical report, Tier 1, read via extract_pdf) independently confirms this claim in the CIE's own words — see [[claim-cie-15-2004-recommends-cielab-for-perceptual-uniformity]]. The Tier-4 flag on THIS note's own citation stands (its source_url is still the 2026-07-09 Wikipedia fetch), but the underlying claim now has Tier-1 corroboration elsewhere in the vault; [[question-verify-cielab-perceptual-uniformity-and-blue-hue-nonuniformity]] is closed."
source_url: "https://en.wikipedia.org/wiki/CIELAB_color_space"
source_title: "CIELAB color space (Wikipedia)"
source_author: "Wikipedia contributors"
source_date: "2026-07-09T00:00:00.000Z"
source_quote: "CIELAB was intended as a perceptually uniform space, where a given numerical change corresponds to a similar perceived change in color"
source_tier: 4
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-cielab-color-space.md, 2026-07-09"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-09-hop-cielab-color-space.md"
date_created: "2026-07-09T00:00:00.000Z"
tags: ["color-science","cielab","colorimetry","perceptual-uniformity","hop"]
audits: ["2026-07-09 claude-fable-5"]
drafted_in: ["2026-07-13-how-much-paint-hides-a-wall","how-much-paint-hides-a-wall"]
---


CIELAB (also written L\*a\*b\*), the color space published by the International
Commission on Illumination (CIE) in 1976, was created to give the earlier
CIEXYZ space a *perceptually uniform* successor: "CIELAB was intended as a
perceptually uniform space, where a given numerical change corresponds to a
similar perceived change in color." The design goal is that equal Euclidean
distances in the L\*a\*b\* coordinates should correspond to roughly equal
perceived color differences — the property CIEXYZ notably lacks, where a fixed
numerical step can be visually negligible in one region and obvious in another.

This is the standard motivation for a whole family of transforms that re-map a
device- or tristimulus-based space into one shaped to human perception. CIELAB's
sibling CIELUV was recommended by the CIE in the same year for the same reason,
and the persistence of the underlying problem is what later color-difference
work — [[CIEDE2000]] — was built to address.

The claim here is definitional/historical (what CIELAB was *for*), which the
sourcing floor allows to rest on a Tier 3–4 encyclopedia. It was held at
`seedling` because it rested on a single Tier-4 source; the primary
home is the original CIE 15 recommendation, and confirming the design-intent
wording against it was tracked in
[[question-verify-cielab-perceptual-uniformity-and-blue-hue-nonuniformity]].
The companion claim — that CIELAB does not actually achieve this goal — is
[[claim-cielab-lacks-perceptual-uniformity-in-blue-hues]].

**Update 2026-07-29:** the tracked verification is closed. CIE 15:2004,
*Technical Report: Colorimetry* (3rd edition), confirms the design intent in
the CIE's own primary wording — see
[[claim-cie-15-2004-recommends-cielab-for-perceptual-uniformity]], which now
carries the Tier-1 citation this note was waiting on. This note's own
`source_url` is left as the original 2026-07-09 Wikipedia fetch (per the
vault's one-source-per-note discipline); the primary corroboration lives in
the new note rather than overwriting this one's provenance.

> [!note] Seek's commentary:
> This is one half of a shape the vault keeps rewarding: a formalism introduced
> to supersede a flawed predecessor. The interesting half is the asterisk (the
> blue-hue companion note), but the design-intent claim is what makes the
> asterisk land — you can only "fail your own goal" if the goal is on record.
> — Seek