Multispectral estimation of retinal photoreceptoral inputs

Bará, Salvador; Bonmatí-Carrión, María Ángeles; Madrid, Juan Antonio; Rol, María Ángeles; Zamorano, J.

doi:10.4302/plp.v11i3.920

Cited by 5 publications

(6 citation statements)

References 4 publications

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“…3a. The zero-point luminances corresponding to blackbody radiation with CCT comprised between 1500 K and 7500 K (Bará, 2019) are also shown for comparison. In Figure 3b we show for completeness the corresponding scotopic zero-point luminances, that is, the zero points 0 (scotopic) to be used in equation (9) to transform the Johnson-Cousins V-band mpsas to the luminances that would be perceived by a human eye under fully dark adaptation (see Section 2).…”

Section: Zero-point Luminances In the V Band For Spectra Recored At Dmentioning

confidence: 99%

“…A widely used transformation between Johnson-Cousins V mpsas and visual brightness in nanoLamberts (nL) has been proposed by Garstang (1986Garstang ( , 1989, based on previous results by Allen (1973), and is still routinely applied in many works. However, this transformation is strictly valid only for blackbody radiation of a specific temperature (Bará, 2019). As a matter of fact, no single zeropoint luminance with universal validity can be assigned to such transformation, because it depends not only on the particular definition of the intervening photometric bands (Bessell, 2005;Carroll & Ostlie, 2007) but also, and very significantly, on the spectral composition of the incoming light.…”

Section: Introductionmentioning

confidence: 99%

“…In previous works we developed a consistent definition of an absolute mpsas system for the human visual system (Bará, 2017), and reported the conversion factors for determining the luminance of blackbody radiation of arbitrary temperature as a function of its mpsas brightness in the Johnson-Cousins B, V, and R photometric bands (Bará, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Magnitude to luminance conversions and visual brightness of the night sky

Bará

Aubé

Barentine

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The visual brightness of the night sky is not a single-valued function of its brightness in other photometric bands, because the transformations between photometric systems depend on the spectral power distribution of the skyglow. We analyze the transformation between the night sky brightness in the Johnson-Cousins V band (m V , measured in magnitudes per square arcsecond, mpsas) and its visual luminance (L, in SI units cd m -2 ) for observers with photopic and scotopic adaptation, in terms of the spectral power distribution of the incident light. We calculate the zero-point luminances for a set of skyglow spectra recorded at different places in the world, including strongly light-polluted locations and sites with nearly pristine natural dark skies. The photopic skyglow luminance corresponding to m V =0.00 mpsas is found to vary between 1.11-1.34 x 10 5 cd m -2 if m V is reported in the absolute (AB) magnitude scale, and between 1.18-1.43 x 10 5 cd m -2 if a Vega scale for m V is used instead. The photopic luminance for m V =22.0 mpsas is correspondingly comprised between 176 and 213 µcd m -2 (AB), or 187 and 227 µcd m -2 (Vega). These constants tend to decrease for increasing correlated color temperatures (CCT). The photopic zero-point luminances are generally higher than the ones expected for blackbody radiation of comparable CCT. The scotopic-to-photopic luminance ratio (S/P) for our spectral dataset varies from 0.8 to 2.5. Under scotopic adaptation the dependence of the zero-point luminances with the CCT, and their values relative to blackbody radiation, are reversed with respect to photopic ones.

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Section: Zero-point Luminances In the V Band For Spectra Recored At Dmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnitude to luminance conversions and visual brightness of the night sky

Bará

Aubé

Barentine

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…This approach seeks to reduce their excessive light emissions, especially the most detrimental ones, and is formulated basically (although not exclusively) in terms of intensive quantities, that is, indicators of relative performance. Some examples of these intensive quantities are the fraction of light emitted by a luminaire toward the upper hemisphere, the average number of lumen per square meter (lx) on the lit surfaces, the fraction of the light emitted by a lamp that effectively reaches the area intended to be illuminated (utilization factor), the luminous efficacy of the lighting system, measured in lm per W, or the relative spectral content of the light, usually described by CCT for visual purposes and by other metrics for non-visual applications (Bará et al, 2019b;Galadí-Enríquez, 2018;Lucas et al, 2014;Rea and Figueiro, 2016;Rea et al, 2012;Sánchez de Miguel et al, 2019).…”

Section: Local Sources Control: Necessary But Not Sufficientmentioning

confidence: 99%

Keeping light pollution at bay: a red-lines, target values, top-down approach

Bará¹,

Falchi²,

Lima³

et al. 2021

Preprint

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The prevailing regulatory framework for light pollution control is based on establishing conditions on individual light sources or single installations (regarding features like ULOR, spectrum, illuminance levels, glare, ...), in the hope that an ensemble of individually correct lighting installations will be effective to somehow solve this problem. This "local sources" approach is indeed necessary, and shall no doubt be enforced; however, it seems to be clearly insufficient for curbing the actual process of degradation of the night, and for effectively attaining the necessary remediation goals. In this paper we describe a complementary (not substitutive) 'red-lines' strategy that should in our opinion be adopted as early as possible in the policies for light pollution control. This top-down approach seeks to set definite limits on the allowable degradation of the night, providing the methodological tools required for making science-informed public policy decisions and for managing the transition processes. Light pollution abatement should routinely be included as an integral part of any territorial management plan. A practical application case-study is described to illustrate these concepts.

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“…We also have rods peaking at 498 nm [9,10,17], which we use for dim light vision. All human photoreceptors have broad spectral half-widths of roughly 100 nm [20]. Apart from rods and cones, the eye contains intrinsically light-sensitive retinal ganglion cells (ipRGCs) peaking at 480 nm [2,[21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Quantifying biologically essential aspects of environmental light

Nilsson

Smolka

2021

J. R. Soc. Interface.

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Quantifying and comparing light environments are crucial for interior lighting, architecture and visual ergonomics. Yet, current methods only catch a small subset of the parameters that constitute a light environment, and rarely account for the light that reaches the eye. Here, we describe a new method, the environmental light field (ELF) method, which quantifies all essential features that characterize a light environment, including important aspects that have previously been overlooked. The ELF method uses a calibrated digital image sensor with wide-angle optics to record the radiances that would reach the eyes of people in the environment. As a function of elevation angle, it quantifies the absolute photon flux, its spectral composition in red–green–blue resolution as well as its variation (contrast-span). Together these values provide a complete description of the factors that characterize a light environment. The ELF method thus offers a powerful and convenient tool for the assessment and comparison of light environments. We also present a graphic standard for easy comparison of light environments, and show that different natural and artificial environments have characteristic distributions of light.

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Multispectral estimation of retinal photoreceptoral inputs

Cited by 5 publications

References 4 publications

Magnitude to luminance conversions and visual brightness of the night sky

Magnitude to luminance conversions and visual brightness of the night sky

Keeping light pollution at bay: a red-lines, target values, top-down approach

Quantifying biologically essential aspects of environmental light

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