Experimentation was conducted to examine the performance of two instruments in predicting the perceptual gloss levels of patches of various colors. To explore this question, the ISO/IEC 19799 Differential Gloss Test chart was printed on a variety of substrates using a variety of inks
on several printers. These printing combinations spanned a significant range of apparent gloss levels. The cyan, magenta, yellow, and black patches off the test targets were measured using both a traditional glossmeter and a μ-goniophotometric device developed at the Rochester Institute
of Technology. This device, previously described in detail in the literature, measures specular reflection at all angles, not just the one equal and opposite angle to the light source as is done with a traditional glossmeter, creating a curve or Bi-directional Reflectance Distribution Function
(BRDF) for the sample measured. In addition, the device generates a series of these curves along the length of the captured gloss band of the sample, allowing a measure of the variability of the specular light, σ, to be calculated. Previous psychophysical experimentation indicated that
the width of the peak of the BRDF curve was found to be an excellent predictor of the appearance of gloss for black patch samples when used in conjunction with the gloss variability. Additional characteristics of this curve such as the height of the peak and the total area under the peak may
be useful in relating physical measurements of specular reflection to the appearance of gloss. Possible useful relationships between these elements of the BRDF feature vector and the gloss appearance for patches of varied colors were examined using data generated by a psychophysical experiment
comprising an anchored scaling technique in which the patches are visually assessed with respect to two reference patches, one having low apparent gloss and one having a high level of apparent gloss. The performance of this device relative to that of a traditional glossmeter when measuring
uniform color patches was examined.
Document Type: Research Article
Publication date: January 1, 2007
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