QA Report: Colour Engineering Toolkit

[xsscx]

QA Report: Colour Engineering Toolkit (CET) Issue

2026-08-18 01:35:18 UTC

Proposed Corrections

CIE94 reference weighting

File: ColourEngineeringToolbox/difference/cie94.m
Use reference chroma, rather than mean reference/sample chroma, for the CIE94 chroma and hue scale factors.

References

• CIE 116:1995, Industrial Colour-Difference Evaluation:
  https://www.cie.co.at/publications/industrial-colour-difference-evaluation
• Bruce Lindbloom's published equation summary explicitly defines
  S_C = 1 + K_1*C_1 and S_H = 1 + K_2*C_1, where C_1 is the reference
  chroma:
  http://www.brucelindbloom.com/Eqn_DeltaE_CIE94.html

Confidence: Moderate; The proposed equation matches the published CIE94 formula

Reproduction

% Before: 1.379995536663367
% Proposed: 1.395038867858738
cie94([50 2.6772 -79.7751],[50 0 -82.7485])

Other Findings

2. d(65) dispatch
   • Currently: Returns Illuminant A
   • Proposed: Returns D65
3. Invalid difference weights
   • Currently: Undefined kL/weight variables
   • Proposed: Named validation errors
4. Valid LUT input
   • Currently: Incorrectly rejected
   • Proposed: [0.25 0.50 0.75]
5. Euclidean dimensions
   • Currently: Unrelated indexing failure
   • Proposed: Named dimension-mismatch error
6. CIECAM02 Cartesian coordinates
   • Currently: ac/bc disagree with polar conversion
   • Proposed: Match Ccosd(h) and Csind(h)
7. Inverse CIECAM02 "average"
   • Currently: Undefined variable c
   • Proposed: XYZ round-trip succeeds

Patches

In Process

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[xsscx]

Adding @PhilGreen736767 for Insight, Discussion & Analysis

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Patch Fork

@PhilGreen736767 Patch Fork at https://github.com/xsscx/colour-engineering-toolbox for Review & Discussion