Colour rendering index (CRI) is a widely used measurement for describing how “accurately” a light source can visually reproduce the colour of an object (compared to a reference light source). This has become more important, as new light sources such as LEDs are more commonly being used in home and commercial environments.
Understanding the difference between a lightsource and an illuminant may sound trivial but needs clarification nonetheless. Even if these terms are clear there might be confusion about choosing the correct illuminant for a professional color quality control. This document provides an overview concerning the standard illuminants on the market.