As digital methods are increasingly used in graphics-related industries, there is a growing reliance on numerical control of the quality of printed materials, being both easier and faster than the visual evaluation the human eye can manage. However, since ultimately the final materials are intended to be seen by the human eye, the final measurement results must closely resemble the human eye results of visual evaluation.
The fact that the paper on which materials are printed influences the final viewed color is a potential problem. Fluorescent whitening agents (FWAs) are contained in many kinds of paper used for printing to give paper a brighter appearance, which can have a particularly large effect on the color of the printed materials when they’re viewed under Illuminant D50*1. For that reason, ISO 13655-2009*2 defined Measurement Condition M1 as having illumination corresponding to CIE Illuminant D50, which minimizes differences in measurement results due to paper fluorescence. This effect was very difficult to measure with conventional, previously available, handheld spectrodensitometers.