Calibration of Gloss Measurements

摘要

Print gloss and attributes such as differential gloss and gloss uniformity are closely related to the specular reflectance characteristics of printed images. An instrument has been developed for the quantitative measurement of the specular reflectance of printed images based on gonio-photometric and micro-densitometric techniques. The device, called a micro-goniophotometer, can be calibrated to known reference materials and produce quantitative analytical information on the specular reflectance of printed materials. The reflectance factors are resolved both angularly, to yield a BRDF, and spatially to provide a measure of gloss variation resolved to the micro-scale. As a result, the causes of gloss differences can be parsed into differences in (a) angular distribution of reflected light, (b) optical constants of the materials, and (c) sub-structural reflectance factors. Examples of the application of the instrument to the characterization of different types of gloss phenomena will be presented along with a description of the configuration and calibration of the instrument.