Abstract
Gilchrist (1980) claimed that large effects of depth on lightness require a display with an overall luminance range substantially larger than the 30:1 range from white to black. But in 2009 Radonjic and Gilchrist obtained an equally large lightness effect using a display with a 30:1 range, though with greater articulation in each plane. Their stimulus consisted of two equally illuminated Mondrian patterns (twenty patches in each) meeting at a dihedral angle. One pattern was composed of only light gray patches, between white and middle gray. The other had only dark gray patches, from middle gray to black. Their data showed a dramatic gamut expansion; the range of perceived grays within each Mondrian was much larger than the actual range. To test whether increased articulation would produce an even greater expansion, we created two Mondrians with the same low range but higher articulation −150 patches within each. The two Mondrians were arranged in the form of a dihedral angle and suspended in midair within a vision tunnel. The left Mondrian contained patches ranging from Munsell 2 to 4.5, while the right Mondrian ranged from 4.5 to 9.5. Fifteen observers viewed the display binocularly and matched 4 target patches in each Mondrian using a Munsell chart. We obtained an even greater perceptual expansion than the earlier study. The mean Munsell matches ranged from 3.1 to 9.0 for the light gray Mondrian, and 3.1 to 9.2 for the dark gray Mondrian. In a second study, 15 observers viewed the Vermeer painting “A View of Delft” on a computer monitor and made Munsell matches to seven surfaces depicted, three in the sunlight and four in the shadow. Although the targets in the shadow varied in lightness from Munsell 3 to 5.5, the mean matches ranged from 3 to 7.0.
NSF (BCS - 1027093) NIH (BM 60826-02).