ESTIMATION OF THE SPARKLE TEXTURE EFFECT BY VISUAL AND INSTRUMENTAL ASSESSMENTS (PO40, Pages 395-400)

To validate the instrumental measurement of sparkle by the BYK-mac multi-angle spectrophotometer, the correlation between the sparkle magnitude assigned by observers and the sparkle magnitude calculated by the instrument was studied by using a psychophysical experiment. The method used for the visual assessment was the method of magnitude estimation. Observers were asked to assign numbers in proportion to the magnitude of a stimulus taking into account two references (extreme anchors). It was found that sparkle grade (SG) correlates very well with human visual perception. The performance is slightly better for 15°as15° measurement geometry than for 45°as45° measurement geometry. However, sparkle intensity (Si) and sparkle area (Sa) do not correlate well with visual perception for any measurement geometry. It could be because the psychophysical experiment was designed to evaluate the sparkle grade and not to evaluate the two independent variables, although relevant for the final sparkle value.