121:(CIE) established the scotopic luminous efficiency function, V'(λ). However, there was still no system of mesopic photometry. This lack of a proper measurement system can lead to difficulties in relating light measurements under mesopic luminances to visibility. Due to this deficiency, the CIE established a special technical committee (TC 1-58) for collecting the results of mesopic visual performance research.
125:
the use of more electric energy than might otherwise be needed. The energy-savings potential of using a new way to measure mesopic lighting scenarios is significant; superior performance could in certain cases be achieved with as much as 30 to 50% reduction in the energy use comparing to the high pressure sodium lights.
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Two very similar measurement systems were created to bridge the scotopic and photopic luminous efficiency functions, creating a unified system of photometry. This new measurement has been well-received because the reliance on V(λ) alone for characterizing night-time light illumination can result in
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curves defined by the two organizations have very different shapes. The weighted function is intended to define "visual effectiveness", i.e. how helpful a light source is in helping human spot an object, rather than any perceived level of luminance. Variation in how this "effectiveness" is rated
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There is not one single luminescence value where photopic vision and scotopic vision meet. there is a wide zone of transition between them. Because it is between photopic and scotopic vision, it is usually called the zone of mesopic vision. The reason that the zone of mesopic vision exists is
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The traditional method of measuring light assumes photopic vision and is often a poor predictor of how a person sees at night. Typically research in this area has focused on improving street and outdoor lighting as well as
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Goodman T, Forbes A, Walkey H, Eloholma M, Halonen L, Alferdinck J, Freiding A, Bodrogi P, Varady G, Szalmas A. Mesopic visual efficiency IV: a model with relevance to nighttime driving and other applications.
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because the activities of neither cones nor rods is simply switched 'on' or 'off'. There are reasons to believe that the cones and the rods both operate in all luminescence conditions.
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374:. Various weighting functions are in use, for blue-heavy and red-heavy light sources, as proposed by two organizations, MOVE and Lighting Research Center (LRC).
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Human eyes respond to certain light levels differently. This is because under high light levels typical during daytime (photopic vision), the eye uses
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The rods have a different wavelength sensitivity, causing blue objects to appear brighter and red objects to appear darker. This is called the "
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Yandan Lin, Dahua Chen, Wencheng Chen. "The significance of mesopic visual performance and its use in developing a mesopic photometry system",
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Rea M, Bullough J, Freyssinier-Nova J, Bierman A. A proposed unified system of photometry. Lighting
Research & Technology 2004; 36(2):85.
117:(light measurement); all measurements were based on the photopic spectral sensitivity function V(λ) which was defined in 1924. In 1951, the
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to process light. Under very low light levels, corresponding to moonless nights without artificial lighting (scotopic vision), the eye uses
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to process light. At many nighttime levels, a combination of both cones and rods supports vision. Photopic vision facilitates excellent
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Stockman, A.; Sharpe, L. T. (2006). "Into the twilight zone: the complexities of mesopic vision and luminous efficiency".
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Cinematographers intentionally emulate mesopic effects to make scenes look darker than a display can actually achieve.
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under low-light (but not necessarily dark) conditions. Mesopic levels range approximately from 0.01 to 3.0
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under scotopic vision. Mesopic vision falls between these two extremes. In most nighttime environments, enough
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As a result of guadually switching from cones to rods in processing light, a number of visual effects occur:
737:"Mesopic Street Lighting Demonstration and Evaluation Final Report for Groton Utilities Groton, Connecticut"
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is the scotopic luminosity function (peaking at approx. 1700 lm/W at 507 nm), and standardized by
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Spatial acuity decreases linearly with log-luminance. A varying "noise" slowly becomes more prominent.
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CIE Publication No. 81. Mesopic photometry: history, special problems and practical solutions. 1989.
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Jacobs, David E.; Gallo, Orazio; A. Cooper, Emily; Pulli, Kari; Levoy, Marc (8 May 2015).
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CIE Publication No. 41. Light as a true visual quantity: principles of measurement. 1978.
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is the standard photopic luminosity function (peaking at 683 lm/W at 555 nm) and
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44:. Most nighttime outdoor and street lighting conditions are in the mesopic range.
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ISO/CIE 23539:2023 CIE TC 2-93 Photometry – The CIE system of physical photometry
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Color appears desaturated and hues change, drifting towards a dull purple.
712:"Driver Response to Peripheral Moving Targets under Mesopic Light Levels"
838:"Circadian Regulation of the Rod Contribution to Mesopic Vision in Mice"
608:"Simulating the Visual Experience of Very Bright and Very Dark Scenes"
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Photopic and
Scotopic lumens – 4: When the photopic lumen fails us
242:{\displaystyle V_{m}(\lambda )=(1-x)V'(\lambda )+xV(\lambda )}
742:. Lighting Research Center Rensselaer Polytechnic Institute.
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678:, Volume 41, Issue 2, February 2006, Pages 117–125.
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113:Prior to 1951, there was no standard for scotopic
790:Zele, Andrew J.; Cao, Dingcai (22 January 2015).
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792:"Vision under mesopic and scotopic illumination"
569:Outdoor Lighting: Physics, Vision and Perception
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16:Ability to see in low light conditions
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157:can be written as the weighted sum,
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699:Lighting Research & Technology
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528:10.1111/j.1475-1313.2006.00325.x
70:In the words of Duco Schreuder:
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643:"Mesopic Vision and Photometry"
378:MOVE and LRC weighting factors
67:prevents true scotopic vision.
854:10.1523/JNEUROSCI.0486-22.2022
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309:{\displaystyle V'(\lambda )}
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842:The Journal of Neuroscience
275:{\displaystyle V(\lambda )}
129:Mesopic luminosity function
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572:. Berlin & New York:
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809:10.3389/fpsyg.2014.01594
676:Building and Environment
150:{\displaystyle \lambda }
24:, sometimes also called
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516:Ophthalmic Physiol. Opt
566:Schreuder, D. (2008).
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367:{\displaystyle L_{p}}
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61:barely perceptible
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337:{\displaystyle x}
108:aviation lighting
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774:. ISO/CIE. 2023.
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57:color perception
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621:(3): 1–15.
391:Blue-heavy
884:Categories
501:References
394:Red-heavy
115:photometry
101:Photometry
346:luminance
301:λ
267:λ
234:λ
216:λ
196:−
181:λ
145:λ
42:luminance
872:36216501
832:(Review)
828:25657632
802:: 1594.
574:Springer
536:16684149
294:′
209:′
30:photopic
863:9698662
819:4302711
544:6184209
895:Vision
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720:9 June
651:9 June
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399:(cd/m)
253:where
740:(PDF)
715:(PDF)
646:(PDF)
611:(PDF)
540:S2CID
479:1.00
462:1.00
445:0.11
428:0.01
49:cones
868:PMID
824:PMID
722:2011
653:2011
578:ISBN
532:PMID
476:0.98
473:1.00
470:0.98
459:0.68
456:1.00
453:0.70
442:0.34
439:0.28
436:0.42
425:0.00
422:0.04
419:0.13
416:0.01
411:LRC
408:MOVE
402:MOVE
320:and
53:rods
38:cd/m
32:and
890:Eye
858:PMC
850:doi
814:PMC
804:doi
623:doi
524:doi
450:1.0
433:0.1
405:LRC
322:ISO
318:CIE
40:in
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