Photopic vision
Photopic visionis thevisionof theeyeunder well-lit conditions (luminancelevels from 10 to 108cd/m2). In humans and many other animals, photopic vision allowscolor perception,mediated bycone cells,and a significantly highervisual acuityand temporal resolution than available withscotopic vision.
The human eye uses three types of cones to sense light in three bands of color. Thebiological pigmentsof the cones have maximum absorption values at wavelengths of about 420 nm (blue), 534 nm (bluish-green), and 564 nm (yellowish-green). Their sensitivity ranges overlap to provide vision throughout thevisible spectrum.The maximumefficacyis 683lm/W at a wavelength of 555 nm (green).[1]Bydefinition,light at a frequency of5.4×1014hertz(λ = 555.17. . . nm)has a luminous efficacy of 683 lm/W.
The wavelengths for when a person is in photopic vary with the intensity of light. For the blue-green region (500 nm), 50% of the light reaches the image point of theretina.[2]
Adaptationis much faster under photopic vision; it can occur in 5 minutes for photopic vision but it can take 30 minutes to transition from photopic toscotopic.[2]
Most older adult humans lose photopic spatial contrast sensitivity. Adults in their 70s tend to require about 30–60% more contrast to detect highspatial frequenciesthan adults in their 20s.[3]
The human eye uses scotopic vision under low-light conditions (luminance level 10−6to 10−3.5cd/m2), andmesopic visionin intermediate conditions (luminance level 10−3to 100.5cd/m2).
See also
[edit]- Adaptation (eye)
- Candela
- Cone cell
- Contrast (vision)
- Mesopic vision
- Night vision
- Purkinje effect
- Photometry (optics)
- Photosensitive ganglion cell
- Scotopic vision
References
[edit]- ^Pelz, J. (1993). Leslie D. Stroebel, Richard D. Zakia (ed.).The Focal Encyclopedia of Photography(3E ed.).Focal Press.p.467.ISBN978-0-240-51417-8.
683 luminous efficacy.
- ^ab"Molecular Expressions".Archivedfrom the original on 2017-12-16.Retrieved2013-03-18.
- ^Burton, Kerri B.; Cynthia Owsley; Michale E. Sloane (4 June 1992). "Aging and Neural Spatial Contrast Sensitivity: Photopic Vision".Vision Research.33(7): 939–949.doi:10.1016/0042-6989(93)90077-a.PMID8506637.S2CID26003597.