Defocus changes the visual contrast sensitivity function, thereby creating a complex curve with local dips and peaks. Since underwater vision in humans is severely defocused, we used optical theory and the phenomenon of spurious resolution to predict how well humans can see in this environment. The values obtained correspond well with experimental measurements of underwater human acuity from earlier studies and even point to an opportunity for humans with exceptional contrast sensitivity to see better underwater than the children in those studies. The same theory could be useful when discussing the visual acuity of amphibious animals, as they may use pupil constriction as a means of improving underwater vision.
© 2004 Optical Society of America
(110.4100) Imaging systems : Modulation transfer function
(330.1070) Vision, color, and visual optics : Vision - acuity
(330.1800) Vision, color, and visual optics : Vision - contrast sensitivity
(330.4060) Vision, color, and visual optics : Vision modeling
(330.7320) Vision, color, and visual optics : Vision adaptation
Anna Gislén and Lars Gislén, "On the optical theory of underwater vision in humans," J. Opt. Soc. Am. A 21, 2061-2064 (2004)