ISO/CIE 11664-4:2019 PDF
Colorimetry — Part 4: CIE 1976 L*a*b* colour space
Colorimetry — Part 4: CIE 1976 L*a*b* colour space
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 8
- Дата публикации:
- 19 июня 2019 г.
- Издание:
- ISO/CIE IS 11664 edition 1 version 1
- ICS:
- 17.180.20
This document specifies a method of calculating the coordinates of the CIE 1976 L*a*b* colour space, including correlates of lightness, chroma and hue. It includes two methods for calculating Euclidean distances in this space to represent the perceived magnitude of colour differences. This document is applicable to tristimulus values calculated using colour-matching functions of the CIE 1931 standard colorimetric system or the CIE 1964 standard colorimetric system. This document can be used for the specification of colour stimuli perceived as belonging to a reflecting or transmitting object, where a three-dimensional space more uniform than tristimulus space is required. This document does not apply to colour stimuli perceived as belonging to an area that appears to be emitting light as a primary light source, or that appears to be specularly reflecting such light. This document is applicable to self-luminous displays, such as cathode ray tubes, if they are being used to simulate reflecting or transmitting objects and if the stimuli are appropriately normalized. Calculating the reverse transformation is shown in Annex A.
Abstract
Overview
ISO/CIE 11664-4:2019 defines the calculation method for the CIE 1976 Lab (CIELAB) colour space*, a widely used approximately-uniform three-dimensional colour space in colorimetry. The standard specifies how to compute L* (lightness), a* and b* coordinates from tristimulus values, provides correlates of lightness, chroma and hue, and gives two equivalent Euclidean methods to calculate colour differences (ΔEab). Annex A shows the reverse transformation. The standard applies when tristimulus values are derived using the CIE 1931 (2°) or CIE 1964 (10°) standard colorimetric observers.
Key topics and requirements
- Calculation formulas for L*, a*, b* from tristimulus values X, Y, Z normalized to a specified white point (Xn, Yn, Zn).
- Correlates: computation of CIE 1976 chroma (Cab*) and hue angle (hab).
- Colour-difference metrics: two equivalent Euclidean definitions for ΔEab (CIELAB ΔE) and decomposition into ΔL*, ΔC*, ΔH*.
- Observer/angular subtense guidance: use CIE 1931 (2°) functions when stimulus subtends ~1°–4°; use CIE 1964 (10°) for larger fields.
- Scope limitations: intended for colours perceived as reflecting or transmitting objects; not for primary self-luminous emissions or specular reflections, except when displays simulate objects and are normalized.
- Reporting and measurement: CIELAB values should be accompanied by measurement and calculation conditions (observer, illuminant, normalization).
- Reverse transform: informative Annex A outlines converting back to tristimulus values.
Applications and who uses it
- Quality control and specification of colour in printing, paints, textiles, plastics, and coatings.
- Color management and device profiling for imaging, photography, and display calibration where CIELAB serves as a perceptually-relevant working space.
- Spectrophotometry and colour matching laboratories for computing and communicating colour tolerances (ΔEab).
- Researchers and engineers in color science, lighting, and materials who require a standardised method for comparing colour differences.
Related standards
- ISO/CIE 11664-1 - CIE Standard Colorimetric Observers (tristimulus definitions).
- ISO/CIE 11664-2 - CIE standard illuminants (referenced for viewing conditions, e.g., D65).
- CIE S 017 - International Lighting Vocabulary (terms and definitions). Note: More advanced colour-difference formulas (CIEDE2000, CIE94, CMC, DIN99) are outside the scope of this part.
Keywords: CIELAB, CIE 1976 Lab*, colorimetry, colour difference ΔE, tristimulus values, CIE 1931, CIE 1964, lightness, chroma, hue, ΔEab.
Технические детали
- Технический комитет
- CIE - International Commission on Illumination
- SKU
- ISO/CIE 11664-4:2019
Похожие стандарты
Другие стандарты ISO
ISO 8689-1:2000
ДействующийWater quality — Biological classification of rivers — Part 1: Guidance on the interpretation of biological qu…
Overview ISO 8689-1:2000, titled Water quality - Biological classification of rivers - Part 1: Guidance on the interpretation of biological quality data from surveys of benthic macroinvertebrates, is…
ISO/ASTM51540-04(2012)
ОтменёнStandard Practice for Use of a Radiochromic Liquid Dosimetry System (Withdrawn 2020)
Significance and Use4.1 The radiochromic liquid dosimetry system provides a means of measuring absorbed dose in materials (5-7). Under the influence of ionizing radiation, chemical reactions take pla…
ISO/ASTM51204-04
ДействующийStandard Practice for Dosimetry in Gamma Irradiation Facilities for Food Processing (Withdrawn 2013)
Significance and Use4.1 Food products may be treated with ionizing radiation, such as gamma-rays from 60Co or 137Cs sources, for numerous purposes, including control of parasites and pathogenic micro…
ISO/ASTM51431-05
ОтменёнStandard Practice for Dosimetry in Electron Beam and X-Ray (Bremsstrahlung) Irradiation Facilities for Food P…
Significance and Use4.1 Food products may be treated with acceleratorgenerated radiation (electrons and X-rays) for numerous purposes, including control of parasites and pathogenic microorganisms, in…
ISO/ASTM52628-20e1
ДействующийStandard Practice for Dosimetry in Radiation Processing
1.1 This practice describes the basic requirements that apply when making absorbed dose measurements in accordance with the ASTM E61 series of dosimetry standards. In addition, it provides guidance o…
ISO/ASTM52921-13(2019)
ДействующийStandard Terminology for Additive Manufacturing—Coordinate Systems and Test Methodologies
Significance and Use 3.1 Although many additive manufacturing systems are based heavily upon the principles of Computer Numerical Control (CNC), the coordinate systems and nomenclature specific to CN…
ISO/ASTMTR52917-EB
ДействующийAdditive Manufacturing — Round Robin Testing — General Guidelines
This document outlines the steps with regard to aspects of design to conduct and run a round robin study (RRS) to assess the degree of variability in an additive manufacturing material or process. Th…
ISO/ASTM52901-17(2023)
ДействующийStandard Guide for Additive Manufacturing – General Principles – Requirements for Purchased AM Parts
Scope 1.1 This document defines and specifies requirements for purchased parts made by additive manufacturing. 1.2 It gives guidelines for the elements to be exchanged between the customer and the pa…