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Proceedings Paper

The Value Of Different Standards And Measurement Systems To Determine The Optical Properties Of Paper And For Standardized Color Reproduction
Author(s): Werner Sobotica
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Paper Abstract

Several terms are used to determine the optical properties of paper and board. Brightness, whiteness, diffuse reflectance factor, diffuse blue reflectance factor, specular gloss, spectral reflectivity and whiteness and yellowness are the used terms. The mainly used term is brightness of paper, an important property in many specifications, but this property has no visual perceptual foundation. Instead it is based on the filter chosen to measure the reflectance of pulp in the region most sensitive to the effects, of bleaching. Therefore an increasing demand for a specification of whiteness can be observed. Belonging to the concept of color, whiteness has to be measured and interpreted in the scope of CIE (Commission Internationale l'Eclairage) based on colorimetri tristimulus data transformed to agree with the perceptual assessment of whiteness. Human observers differentiate between the whiteness of the object being viewed and its brightness. A special index of whiteness is needed. No general agreement was so far reached regarding the best index which could and should be adopted universally among the two recommended by the CIE. Nearly every white sample is a little colored, having bluish, greenish or redish tint. In the post no numerical measure of tint was assigned to any of the whiteness indexes. Further problems arise that fluorescent whiteness agents are added to paper and board to increase their whiteness. This requires not only instrumental design and calibration but also the illuminant to be adopted for such measurements.

Paper Details

Date Published: 12 June 1990
PDF: 10 pages
Proc. SPIE 1184, Neugebauer Memorial Seminar on Color Reproduction, (12 June 1990); doi: 10.1117/12.963907
Show Author Affiliations
Werner Sobotica, Consultant (United States)

Published in SPIE Proceedings Vol. 1184:
Neugebauer Memorial Seminar on Color Reproduction
Kazuo Sayanagi, Editor(s)

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