title: Influence of intraocular scattered light on lightness-scaling experiments.
abstract: Following Munsell's bisection procedure [J. Opt. Soc. Am. 23, 394 (1933)], we established a nine-step gray scale in which each step is an equal increment in lightness. We calculated retinal illuminances after intraocular scatter by using the point-spread function of Vos et al. [Vision Res. 16, 215-219 (1976)]. After this correction for intraocular scatter, we find a logarithmic relationship between retinal illuminance and achromatic lightness scales that are determined by the bisection method. Additional bisection experiments with a series of different backgrounds corroborate this result. We find that lightness depends linearly on the logarithm of scatter-corrected retinal illuminance, with different slopes for backgrounds of different lightness. This study also highlights the importance of using scatter-corrected illuminance in any quantitative model of lightness.
mesh_terms: D000328:Adult; D006801:Humans; D008027:Light; D055095:Optics and Photonics; D012160:Retina / Q000502:physiology*; D012542:Scattering, Radiation; D014785:Vision, Ocular / Q000502:physiology*