scope:

This part of ISO 5 specifies the geometric conditions for measuring the reflection density of photographic and graphic art materials.

It specifies illumination at all azimuth angles. These measurements are not sensitive to directional reflections from textured surfaces. It does not cover those situations where light has been deliberately polarized.

Although intended primarily for use in the measurement of the reflection characteristics of processed photographic materials, this part of ISO 5 is also applicable to the measurement of these characteristics for other materials.

This part of ISO 5 serves three primary functions:

a) to aid in the calibration and certification of densitometers, or spectrophotometers used as densitometers, by allowing for the generation of SRMs (Standard Reference Materials) with numerical values traceable to fundamental physical phenomena;

b) to provide the basis for unequivocal measurements that are needed for specifications, communication between organizations, and for contractual agreements;

c) to provide a referee function to resolve seemingly different measurement data between systems.