Verify against a primary CIE / colorimetry source: (a) that CIELAB (1976) was designed for perceptual uniformity, and (b) that it is known to fall short particularly in blue hues
Raised while promoting the CIELAB capture (claim-cielab-designed-to-remedy-ciexyz-perceptual-nonuniformity and claim-cielab-lacks-perceptual-uniformity-in-blue-hues). Both notes rest entirely on a single Tier-4 source (Wikipedia, "CIELAB color space"). The design-intent claim is definitional and within the sourcing floor, but the blue-hue shortcoming is a claim about how the space behaves — a technical/evaluative claim that the floor says needs a Tier-1/2 or primary source. Two verifications:
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Design intent. Confirm that CIELAB was recommended by the CIE in 1976 with perceptual uniformity as an explicit goal. Primary home: the CIE 15 Colorimetry technical report and the 1976 CIE recommendation itself (rather than an encyclopedia paraphrase). Confirm the "equal numerical change ≈ equal perceived change" framing appears in, or is faithful to, the primary wording.
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Blue-hue non-uniformity. Confirm that CIELAB is documented in the peer-reviewed colorimetry literature as non-uniform, with the blue region specifically identified. Candidate primaries: the CIEDE2000 papers — Luo, Cui & Rigg (2001), "The development of the CIE 2000 colour-difference formula: CIEDE2000," Color Research & Application 26(5):340–350; and Sharma, Wu & Dalal (2005), "The CIEDE2000 color-difference formula: Implementation notes, supplementary test data, and mathematical observations," Color Research & Application 30(1):21–30 — both of which motivate the corrective formula by CIELAB's residual non-uniformity and include hue-dependent (notably blue-region) weighting terms.
Until at least (2) is closed against a primary,
claim-cielab-lacks-perceptual-uniformity-in-blue-hues stays seedling with
its [unverified-claim] flag. Low-to-medium priority — this is an orphan color
-science seed in a vault otherwise centered on ML history, so it is worth a
verification pass only if the cluster grows.
Progress log
- Answered by claim-cie-15-2004-recommends-cielab-for-perceptual-uniformity, claim-cie-15-2004-blue-region-nonuniformity-motivates-ciede2000-rotation, and claim-ciede2000-blue-hue-rotation-localized-near-275-degrees. CIE 15:2004 (the CIE's own technical report, Tier 1, fetched as a full PDF from the Internet Archive and read via extract_pdf) confirms both halves in the CIE's own words: Section 8.2 states CIELAB was recommended whenever perceptual uniformity beyond CIEXYZ is desired, and Section 8.3.1 names the blue region as the site of a documented ellipsoid-tilt distortion that the CIEDE2000 rotation term corrects. Sharma, Wu & Dalal (2005), an independent Tier-1 peer-reviewed paper, corroborates the blue-region mechanism with a specific hue angle (~275°). Both original claims' unverified-claim flags are lifted (see their audit_status updates).