Effects of background and contour luminance on the hue and brightness of the Watercolor effect

Abstract

Conjoint measurement was used to investigate the joint influences of the luminance of the background and the inner contour on hue- and brightness filling-in for a stimulus configuration generating a water-color effect (WCE), i.e., a wiggly bi-chromatic contour enclosing a region with the lower luminance component on the exterior. Two stimuli with the background and inner contour luminances covarying independently were successively presented, and in separate experiments, the observer judged which member of the pair's interior regions contained a stronger hue or was brighter. Braided-contour control stimuli that generated little or no perceptual filling-in were also used to assess whether observers were judging the interior regions and not the contours themselves. Three nested models of the contributions of the background and inner contour to the judgments were fit to the data by maximum likelihood and evaluated by likelihood ratio tests. Both stimulus components contributed to both the hue and brightness of the interior region with increasing luminance of the inner contour generating an assimilative filling-in for the hue judgments but a contrast effect for the brightness judgments. Control analyses showed negligible effects for the order of the luminance of the background or inner contour on the judgments. An additive contribution of both components was rejected in favor of a saturated model in which the responses depended on the levels of both stimulus components. For the hue judgments, increased background luminance led to greater hue filling-in at higher luminances of the interior contour. For the brightness judgments, the higher background luminance generated less brightness filling-in at higher luminances of the interior contour. The results indicate different effects of the inner contour and background on the induction of the brightness and coloration percepts of the WCE, suggesting that they are mediated by different mechanisms.

Toward reliable measurements of perceptual scales in multiple contexts

“…So far, MLCM has been used, for example, to evaluate the relative effects of physical gloss and roughness on the respective perceptual attributes ( Ho et al., 2008 ), the effect of physical gloss and albedo on perceived gloss and lightness ( Hansmann-Roth and Mamassian, 2017 ), or stimulus’ frequency and amplitude on perceived saturation in the watercolor effect ( Gerardin et al., 2014 , 2018 ). In these cases, the stimulus dimensions were continuous variables, and the conjoint measurement is evaluated with an additive model, in which the perceptual judgments are explained by the sum of the effects of each individual stimulus dimension (Knoblauch and Maloney, 2012 ).…”

“…MLCM has been introduced as an extension of MLDS to model the effect of more than one stimulus dimension onto a single perceived dimension, for example, perceived gloss ( Ho et al., 2008 ; Hansmann-Roth and Mamassian, 2017 ), color ( Rogers et al., 2016 ), or the watercolor effect ( Gerardin et al., 2014 , 2018 ). For the scale estimation, one context is defined as “reference.” Here we use the checkerboard in plain view or the center-surround analogue to plain view as reference (see Methods).…”

Filled/non-filled pairs: An empirical challenge to the integrated information theory of consciousness

“…Subjects viewed pairs of stimuli comprised of identical or different images and judged whether the images were the same or different (see Figure 5c). A free-viewing procedure (Pinna 1987;Pinna, Brelstaff, and Spillmann 2001;Devinck, Delahunt, Hardy, Spillmann, et al 2005;Devinck, Hardy, et al 2006;Devinck and Spillmann 2009;Devinck and Knoblauch 2012;Gerardin, Dojat, et al 2018) was used to encourage judgements based on foveal views of the stimuli.…”

“…The filled watercolor stimulus came in two kinds: purple fringe (HSV [290, 0.997, 0.6]) with orange inducer (HSV [35, 0.997, 1]) or yellow fringe (HSV [30, 0.98, 0.8]) with blue inducer (HSV [200,0.997,1]). These color combinations (Pinna, Brelstaff, and Spillmann 2001) and brightness (V) ratios, both between the contours as well as between each contour and the background, seem to provoke the strongest filling-in (Devinck, Delahunt, Hardy, Spillmann, et al 2005;Devinck and Knoblauch 2012;Gerardin, Devinck, et al 2014;Coia, Jones, et al 2014;Gerardin, Dojat, et al 2018). To optimize the watercolor effect within-subjects, each participant was presented with both versions at the start of the experiment and asked to choose the stimulus in which they perceived a more opaquely colored ring between the contours (and thus yielded the strongest filling-in).…”

A Better Photometric Index of Photo-Biological Effect on Visual Function of Human Eye: Illuminance or Luminance?

“…Another photometric index luminance also describes the brightness of the lighting environment or lighting source [6]- [8]. However, luminance is not as popular as illuminance due to its complex measurement and analysis.…”