Abstract

Optical brighteners are often used to make yellowish paper or media appear whiter and brighter, resulting in a product that is much more appealing. The operative aspect of optical brighteners is that they use fluorescence to convert ultraviolet light (invisible to human vision) to blue (visible) light. This poses problems for establishing color management profiles using a spectrophotometer to measure spectral reflectance to derive colorimetry of printed colors under arbitrary light sources on media in that the derived colorimetry doesn’t match the actual color appearance, resulting in undesirable color casts in the final printed output using color management.



This session looks at measuring spectral reflectance versus measuring spectral fluorescence and demonstrates that colorants derived from special reflectance of surfaces that have fluorescence can be invalid. A method of simulating spectral fluorescent measurements will be shown, based on an extension of Substrate Correction used in SCCA by first applying the approach to spectral reflectance and then spectral fluorescence.