Abstract

Four odd effects occur when violet lights are desaturated. They turn unaccountably red (Abney effect); if the redness is assessed by an indirect method such as cancellation (which desaturates), they appear to have a latent redness some ten times greater than their apparent redness (Moeller effect); they become much brighter than can be explained by the addition of the desaturant (Guth effect); and they become more, not less, discriminable (Tyndall effect).

© 1987 Optical Society of America