Principles of colorimetry. II. Colorimetry and digital systems

The article discusses some of the reasons why the manipulation of digital images is not as simple as it might appear. Even though the concepts of trichromatic graphics have become familiar, even to the non-specialist, unexpected difficulties can occur when passing from a qualitative empirical description of colour to quantitative calculations or the reproduction of an image on a material support, such as fabric. A theoretical difficulty exists, based on the discrepancy between electronic graphics based on three co-ordinates and colorimetry, based on as many as 31 intervals. Practical problems in reconciling what appears on the screen with what can be produced in a printshop are also discussed with reference to both printing and fabric inspection systems. Challenges for the future are noted.