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Shigeki Nakauchi, Ryo Nishijima, Takehiro Nagai, Yusuke Tani, Kowa Koida, Michiteru Kitazaki; Perceptual matching of translucent materials under different illuminant conditions.. Journal of Vision 2012;12(9):867. doi: https://doi.org/10.1167/12.9.867.
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© ARVO (1962-2015); The Authors (2016-present)
INTRODUCTION: Many common materials such as food or human skin have translucent properties and human observers can easily distinguish them from opaque materials. Even when physical translucency of the material is identical, its perceptual translucency is largely affected by illuminant conditions in a complex way because of sub-surface scattering. This study investigates how the illuminant conditions alter the perceptual translucency by a simple matching experiment with translucent materials under two different illuminant conditions.
METHODS: Bottle-shaped objects made from translucent material (polyethylene terephthalate: PET) were used in the experiment. Physical translucency of the bottles was varied in five levels by mixing white coloring agent of 0.25, 0.5, 1.0, 1.7 and 2.5%. Observers were presented simultaneously with a bottle as a test, which was illuminated both from the front and the back, and with all of the five bottles in a standard light booth with a D65 light source as reference stimuli. The observers were instructed to answer which one in the five reference bottles seemed to be most similar to the test bottle. The test bottle was randomly chosen from the five different bottles, and the intensity of the illuminant behind the test bottle (backlight) was varied in five levels. Thus, matching was performed under 25 conditions in total.
RESULTS & CONCLUSIONS: Perceptual translucency of the test bottles was affected with physical translucency of the bottle as expected. Intensity of the backlight also altered the perceptual translucency but not straightforwardly: perceptual translucency did not monotonically increase with the backlight intensity. While RMS contrasts of the test bottle images without highlight regions could well explain the dependency of perceptual translucency both on the physical translucency and the backlight intensity. This supports the view that RMS contrast of non-specular shading is an image cue for matching perceptual translucency.
Meeting abstract presented at VSS 2012
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