9/19/2023 0 Comments Translucent examples materials![]() Indeed, an opaque surface does not appear translucent merely because its contrast is low. On the other hand, they also found that simple image statistics, such as luminance contrast and skewness, do not predict the perceived translucency. (3) As the object becomes more translucent, the luminance contrast of the image (including highlights) is decreased and the spatial edges are blurred. (2) Images of opaque and translucent objects have different luminance histograms but a similar spatial pattern of luminance gradients (isophotes). ![]() Using computer-generated 3D objects, they investigated the relationships between distal and proximal stimulus parameters and perception and reported basic observations, including the following: (1) Highlights are necessary if the object is to be perceived as naturally translucent, i.e., completely matte translucent surfaces do not give a natural impression of translucency. The notable exception is Fleming and Bülthoff ( 2005), who reported an elegant analysis on the perception of translucency. ![]() On the other hand, almost no work has examined how the human visual system estimates the translucency of a 3D object from a single image. ![]() These findings reveal an important information source for the visual estimation of glossiness and bumpiness, even though they do not always entirely explain the perception (Anderson & Kim, 2009 Motoyoshi et al., 2007). Ho, Landy, and Maloney ( 2008) also demonstrated a strong correlation between the luminance contrast of the surface image and the apparent glossiness and bumpiness. For example, Motoyoshi, Nishida, Sharan, and Adelson ( 2007) and Sharan, Li, Motoyoshi, Nishida, and Adelson ( 2008) showed that skewness (or something like it) in a luminance histogram is a robust cue for perceiving glossiness and lightness. Some studies have explored and revealed the textural features of a surface image that are useful as cues for estimating a certain material property. Recently, an increasing number of studies have been employing natural surfaces with complex three-dimensional (3D) structures and examining a variety of attributes, such as glossiness (Beck & Prazdny, 1981 Blake & Bülthoff, 1990 Fleming, Dror & Adelson, 2003 Nishida & Shinya, 1998), bumpiness (Ho, Landy, & Maloney, 2006), and translucency (Fleming & Bülthoff, 2005). Previous work on surface-quality perception has generally addressed the apparent color and lightness of flat and matte surfaces arranged in simple (Heinemann, 1955 Jameson & Hurvich, 1961 Wallach, 1948) or complex (Adelson, 1999 Bloj, Kersten, & Hurlbert, 1999 Boyaci, Maloney, & Hersh, 2003 Brainard, 1998 Gilchrist, 2006) scenes. Humans can effortlessly perceive not only the lightness and color of an object but also various other properties, such as its glossiness and roughness (Adelson, 2001). The results support the notion that the spatial and contrast relationship between specular highlights and non-specular shading patterns is a robust cue for the perceived translucency and transparency of three-dimensional objects. A subsequent experiment further demonstrated that manipulation of the contrast and blur of the non-specular image component dramatically alters the apparent translucency of an opaque object. In a simple rating experiment with computer-generated objects, we show that the non-specular image component tends to be blurred, faint, and even partially contrast-reversed for objects that appear more translucent or transparent. Here, we investigated image features that are diagnostic of the perceived translucency and transparency, focusing on the fact that variations in the opacity of a surface affect largely the non-specular component (shading pattern) of an image and little the specular component (highlights). Translucent materials involve complex optics, such as sub-surface scattering and refraction, but humans can easily distinguish them from opaque materials. Natural surfaces, such as those of food and drink, have translucent properties.
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