Elsevier

Vision Research

Volume 47, Issue 24, November 2007, Pages 3061-3069
Vision Research

Occlusion, transparency, and lightness

https://doi.org/10.1016/j.visres.2007.06.004Get rights and content
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Abstract

The lightness of a visual surface is its perceived achromatic reflectance [Adelson, E. H., (2000). Lightness perception and lightness illusions. In M. Gazzaniga (Ed.), The new cognitive neuroscience (2nd ed.) (pp. 339–351) Berlin: Springer; Gilchrist, A. (1999). Lightness perception. In R. W. F. Keil (Ed.), MIT encyclopedia of cognitive science (pp. 471–472). Cambridge: MIT press]. Lightness ranges from black, through various shades of grey, up to white. Anderson and Winawer [Anderson, B., Winawer, J. (2005). Image segmentation and lightness perception. Nature, 434, 79–83] suggested that perceptual decomposition of image luminance into multiple sources in different layers (e.g., perceptual transparency) is critical to the their lightness illusions. However, I show that simple perceptual occlusion evoked by T-junctions will work as well, suggesting that perceptual scission of luminance into multiple layers is unnecessary for such effects. I argue that the lightness illusions presented by Anderson and Winawer involve fundamentally different mechanisms than previously studied lightness illusions, including those involving perceptual transparency.

Keywords

Lightness
Transparency
Surface perception
Occlusion
Visual perception

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