Overview
ISO 24585-2:2023 - Graphic technology - Multispectral imaging measurement and colorimetric computation for graphic arts and industrial application - Part 2: Requirements for decorative surfaces - defines how to use multispectral imaging to measure, compute and compare the appearance of decorative printed surfaces. The standard specifies instrument, illumination, geometry and data requirements for spatially resolved spectral measurements that are converted to tristimulus images, and it introduces a single-image similarity metric, SIM_PDE, to quantify visual closeness between a reference and a test surface. It also gives recommendations for laboratory specimen preparation and backing.
Key topics and technical requirements
- Scope: Targets decorative surfaces (e.g., woodgrain-printed base papers) - not applicable to functional surfaces.
- Multispectral measurement:
- Mandatory wavelength measurement range 400–700 nm (recommended 380–780 nm).
- Minimum 7 spectral channels; spectral energy across the visible range must be sufficient for low noise.
- Instrument standardization and adjustment per manufacturer instructions; conformance testing recommended.
- Illumination & geometry:
- Continuous spectral power distribution across the visible range; UV-cut (M2) options noted.
- Measurement geometry 45°:0° (influx:efflux), with efflux optic normal to the specimen surface.
- Uniformity: assess at ≥100 evenly spaced positions; illuminance/luminance tolerances specified.
- Spatial resolution & imaging:
- Recommended spatial resolution ≥35 samples/cm; minimum 10 samples/cm horizontally and vertically.
- Shading correction and image storage requirements; tristimulus image computation from spectral data.
- Specimen preparation:
- Backing must be black or white conforming to ISO 13655; guidance and a checklist are provided (Annex A).
- Comparison & metrics:
- Defines SIM_PDE - a single-index measure of average colour difference for image similarity and process acceptance.
- Reporting & conformance:
- Data reporting requirements and conformance criteria included for consistent interoperability.
Practical applications and users
- Industries: decorative printing, wood-based panel manufacturing, laminate and flooring production, digital and conventional printing.
- Use cases: quality assurance, make-ready verification, reprint acceptance, process control, color looping (RIP corrections), dispute resolution.
- Primary users: press operators, QA labs, color scientists, instrumentation manufacturers, and systems integrators deploying inline multispectral imaging for production monitoring.
Related standards
Keywords: ISO 24585-2, multispectral imaging, decorative surfaces, SIM_PDE, tristimulus images, colorimetric computation, spectral measurement, graphic technology, specimen preparation, spatial resolution.