ISO 23603:2005

Overview

ISO 23603:2005 - Standard method of assessing the spectral quality of daylight simulators for visual appraisal and measurement of colour - defines how to evaluate whether a daylight simulator accurately reproduces the spectral irradiance of CIE daylight illuminants (for example D50, D55, D65, D75) for colour viewing and measurement. The standard specifies measurement ranges, chromaticity tolerances, metamerism-based indices and a letter quality grade system (A–E) to report simulator performance for both the visible and ultraviolet spectral regions.

Key topics and technical requirements

• Scope: Assessment of spectral quality of irradiance from daylight simulators used for visual appraisal or colour measurement; assignment of a quality grade.
• Measurement: Relative spectral irradiance must be measured by spectroradiometry over the near-UV and visible range (specified in the standard as 300 nm to 780 nm) at 5 nm intervals or 5 nm bands. Devices that emit significant radiant power below 300 nm are considered unsuitable as daylight simulators.
• Normalization: Spectral irradiance is normalized so assessments are independent of absolute illuminance.
• Chromaticity tolerance: The CIE 1976 u′v′ chromaticity difference between the simulator and the target CIE daylight illuminant shall not exceed 0.015 for the simulator to be graded.
• Metamerism indices: The standard uses sets of virtual metameric pairs and computes visible-range and ultraviolet-range metamerism indices to quantify mismatches caused by spectral differences and fluorescence.
• Quality grades: Separate grades for visible and UV spectral regions are reported as a two-letter code (e.g., “BC”), with A the highest quality.

Applications and who uses it

ISO 23603:2005 is used by professionals who depend on consistent and accurate simulated daylight for colour-critical tasks:

• Lighting manufacturers developing daylight simulator products.
• Color quality/control laboratories and calibration labs validating simulators used in colour measurement.
• Printing, photography and graphic arts where standard illuminants (notably D50) are central to colour matching.
• Paints, textiles and plastics industries for visual colour matching and instrument-based colour measurement.
• Museums, conservation and automotive sectors where accurate daylight appraisal affects appearance assessment.

Related standards

• CIE 15:2004 (Colorimetry)
• CIE 51.2-1999 (previous method for daylight simulator assessment)
• CIE 63-1984 (Spectroradiometry of light sources)
• ISO/CIE 10527 and ISO/CIE 10526 (Colorimetric observers and standard illuminants)

Keywords: ISO 23603:2005, daylight simulators, spectral quality, chromaticity tolerance, metamerism index, spectroradiometry, CIE illuminant, colour measurement, visual appraisal.