ISO 18944:2018

Overview

ISO 18944:2018 - Imaging materials - Reflection colour photographic prints - Test print construction and measurement - specifies how to prepare, print and measure digital test targets used to evaluate image stability of reflection colour photographic prints. The standard defines requirements for digital test file content (sRGB), printer setup and printing procedures, target print conditioning and the measurement of test patches. It also prescribes how to calculate colour and density changes during stability tests. Statistical reduction and psychophysical end-point definitions are intentionally out of scope, although results produced using ISO 18944 feed into print life specifications.

Key topics and technical requirements

• Digital test file preparation
  • Use of sRGB-encoded digital test files (IEC 61966-2-1) for end-user-typical printing.
  • Guidance on constructing and adapting digital files and selecting patch values.
• Printing system configuration
  • Requirements for printer setup, source preparation (including conventional silver gelatin materials), and procedures to generate uniform target prints.
• Target print conditioning and holding
  • Procedures for conditioning prints after printing and defined holding/measurement timing to reduce test-process-induced variation.
• Measurement procedures
  • Measurement timing and environmental/geometric conditions for patch measurement (referencing ISO density and colorimetry practices).
  • Attributes to measure: densitometric values for colour and neutral patches and colorimetric characterization for discoloration (D).
• Calculations of colour change
  • Densitometric methods to compute percent density change in primary, secondary and neutral patches.
  • Color balance shift calculations and colorimetry-based evaluation for selected patches.
• Reporting
  • Requirements for test reporting to ensure reproducibility and comparability of image stability data.

Practical applications and users

ISO 18944 is used to produce reliable, reproducible test prints and measurements for:

• Materials manufacturers (photographic papers, inks, coatings)
• Test laboratories and QA teams conducting image stability and fade testing
• Conservation scientists and archives assessing long-term print permanence
• Researchers developing print life specifications and comparative stability studies
• Suppliers preparing test targets for standardised life expectancy claims

Using ISO 18944 helps ensure consistent sampling of colour space, controlled printing/measurement processes, and comparable data that can be integrated into broader print life specifications.

Related standards

Normative and related references include:

• ISO 5-3, ISO 5-4 (density measurement)
• ISO 11664-4 (CIE Lab*)
• ISO 13655 (spectral measurement)
• ISO 18913 (permanence vocabulary)
• ISO 18941 (ozone fading test)
• IEC 61966-2-1 (sRGB)

Keywords: ISO 18944, imaging materials, reflection colour photographic prints, test print construction, measurement, sRGB, image stability, densitometry, colorimetry, print life.