منابع مشابه
Paradoxical lightness contrast
The visual system's computation of lightness (perceived reflectance) leads to contrast effects in which a gray target region appears lighter on a black background than on a white one. Here we show a paradoxical contrast effect in which targets look lighter after adding regions that increase the scene's average luminance, and darker after adding regions that decrease this luminance. The paradoxi...
متن کاملContext-dependent lightness affects perceived contrast
Perceived contrast of a grating varies with its background (or mean) luminance: of the two gratings with the same photometric contrast the one on higher luminance background appears to have higher contrast. Does perceived contrast also vary with context-dependent background lightness even when the luminance remains constant? We investigated this question using a stimulus in which two equilumina...
متن کاملLightness contrast and failures of constancy: a common explanation.
Observers were asked to select, from a grid of 16 achromatic Munsell chips presented on a white background in bright illumination, a sample to match a light gray chip simultaneously presented on the same white background but in a shadowed region adjacent to the brightly illuminated region. The border dividing the two fields of illumination was made to appear as either a reflec-tance edge or an ...
متن کاملLinking luminance and lightness by global contrast normalization.
In the present experiment we addressed the question of how the visual system determines surface lightness from luminances in the retinal image. We measured the perceived lightness of target surfaces that were embedded in custom-made checkerboards. The checkerboards consisted of 10 by 10 checks of 10 different reflectance values that were arranged randomly across the board. They were rendered un...
متن کاملLightness, brightness, and brightness contrast: 2. Reflectance variation.
Changes of annulus luminance in traditional disk-and-annulus patterns can be perceived to be either reflectance or illuminance changes. In the present experiments, we examined the effect of varying annulus reflectance. In Experiment 1, we placed test and standard patch-and-surround patterns in identical Mondrian patchworks. Only the luminance of the test surround changed from trial to trial, ap...
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ژورنال
عنوان ژورنال: Vision Research
سال: 2010
ISSN: 0042-6989
DOI: 10.1016/j.visres.2009.11.004