Overview
ISO 18314-5:2022 - Analytical colorimetry - Part 5 specifies a standardized procedure and test report for determining small colour differences of object colours according to equidistant (uniform) colour spaces. The standard targets small perceptible colour differences (∆E < 5) for non‑luminous object colours and is applicable to assessments of pigments, dyestuffs and extenders used in coatings, plastics and prints where samples are evaluated in pairs for colour conformity.
Key features:
- Defines a test procedure and minimum test report content.
- Provides three informative metrics (Annexes A, B and C) tied to three uniform colour‑space models: OSA‑UCS (modified by Oleari et al.), DIN99o, and CAM16‑UCS.
- Prepared by ISO/TC 256 (Pigments, dyestuffs and extenders).
Key technical topics and requirements
- Scope and applicability: For non‑luminous object colours with small differences, evaluated pairwise in coatings, plastics and prints.
- Three metric examples (informative):
- Annex A: OSA‑UCS modified by Oleari - includes logarithmic compression of chroma and lightness and formulae to compute ∆E in that space.
- Annex B: DIN99o - parameter adjustments based on CIELAB (ISO/CIE 11664‑4) to produce a colour space and ∆E metric.
- Annex C: CAM16‑UCS - provides a CAM16‑based uniform colour space example for small differences.
- Test report minimum content (shall include):
- Product identification, reference to ISO 18314‑5:2022, chosen colour space model, test results, deviations, anomalies, and test date.
- Reporting requirement: The colour‑difference calculation metric used must be explicitly stated in the test report.
- Limitations: The provided formulae are intended for small differences (∆E < 5). Use for large differences (approx. >10 CIELAB units) can produce significant deviations versus visual evaluation and must be agreed between parties.
Practical applications and users
Who benefits:
- Quality control and laboratory teams in pigment, dyestuff and extender production.
- Colour formulation and matching specialists in coatings, plastics and printing industries.
- R&D groups developing colorants and tolerance criteria.
- Procurement and QA teams specifying colour conformity tolerances in supplier contracts.
Practical uses:
- Quantitative pairwise colour conformity checks during production and incoming inspection.
- Defining tolerance ellipsoids and adjustment actions in colour formulation workflows.
- Harmonizing measurement and reporting across suppliers and customers.
Related standards
- ISO/CIE 11664‑4 (CIELAB) - tristimulus to CIELAB coordinates.
- ISO/CIE 11664‑6 (CIEDE2000) - well‑known colour‑difference formula (note: CIEDE2000 is not itself a UCS).
- CIE 217 - comparative analyses of colour‑difference models referenced by ISO 18314‑5.
Keywords: ISO 18314‑5:2022, analytical colorimetry, colour differences, equidistant colour spaces, OSA‑UCS, DIN99o, CAM16‑UCS, pigments, dyestuff, extenders, coatings, plastics, prints, ∆E, colour conformity, test report.
Open preview (PDF)Analytical colorimetry — Part 5: Procedure for colorimetric determination of colour differences of object colours according to equidistant colour spaces
