Calculation of Mesopic Luminance Using per Pixel S/P Ratios Measured with Digital Imaging

Maksimainen, Mikko; Kurkela, Matti; Bhusal, Pramod; Hyyppä, Hannu

doi:10.1080/15502724.2018.1557526

Cited by 7 publications

(4 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The scotopic luminances 𝐿𝐿 v,scot can be easily obtained by multiplying the photopic ones 𝐿𝐿 v (Eq. 3) by the scotopic-tophotopic luminance ratio (S/P) defined as (Maksimainen et al, 2019):…”

Section: Figure 1 Geometry For the Definition Of Spectral Radiancementioning

confidence: 99%

Magnitude to luminance conversions and visual brightness of the night sky

Bará

Aubé

Barentine

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

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.

show abstract

Section: Figure 1 Geometry For the Definition Of Spectral Radiancementioning

confidence: 99%

Magnitude to luminance conversions and visual brightness of the night sky

Bará

Aubé

Barentine

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Their associated photometric systems are defined, by historical reasons, in terms of energies instead of photon numbers, even if the actual interactions of the radiation with the detectors take place on a photon basis. When working with human visual bands in the photopic, scotopic or mesopic adaptation ranges the in-band radiance, expressed in energy units, can be converted into SI luminous units of cd•m -2 by multiplying it by the corresponding luminous efficacy coefficients, namely 𝐾 = 683 lm•W -1 for photopically adapted eyes, 𝐾′ = 1700 lm•W -1 for scotopically adapted ones, and intermediate values for mesopic adaptation [43].…”

Section: 𝐵 = 𝑆(𝜆)𝐿(𝜆)D𝜆 (A1)mentioning

confidence: 99%

“…The use of the Johnson V band [38][39] is partly motivated by historical reasons and should probably be revised in the near future. From a visual point of view the Johnson V band turns out to be suboptimal: the sky luminance in the photopic [40], scotopic [41], or mesopic [42][43] human vision bands should be routinely reported instead, whereas for large-scale, worldwide light pollution instrument-based measurement and reporting campaigns the scientific photometric system defined for the standard RGB bands [44], such as those used in science-, industry-, and consumer-grade digital cameras [45], seems to be the-most efficient choice. For the purposes of this work, the quality of the urban night sky will be characterized with two metrics commonly used in this field: the total zenith sky brightness in Johnson magV/arcsec 2 , and the photopic artificial zenith luminance, in cd/m 2 .…”

mentioning

confidence: 99%

Can we illuminate our cities and (still) see the stars?

Bará

Falchi²,

Lima³

et al. 2021

IJSL

View full text Add to dashboard Cite

Could we enjoy starry skies in our cities again? Arguably yes. The actual number of visible stars will depend, among other factors, on the spatial density of the overall city light emissions. In this paper it is shown that reasonably dark skies could be achieved in urban settings, even at the center of large metropolitan areas, if the light emissions are kept within admissible levels and direct glare from the light sources is avoided. These results may support the adoption of science-informed, democratic public decisions on the use of light in our municipalities, with the goal of recovering the possibility of contemplating the night sky everywhere in our planet.

show abstract

“…A functional model based on the chromaticity-guided was built for lighting applications of the trichromatic light source in both photopic and mesopic conditions [24]. Maksimainen developed a measurement technology by use of a calibrated digital camera to acquire pixel-wise S/P ratio and further calculated the mesopic luminance [25]. Shin proposed a mesopic color appearance model, which could be used to simulate color appearance in the mesopic range as well as photopic and scotopic conditions by adding rod intrusion to the two-stage model [26,27].…”

Section: Introductionmentioning

confidence: 99%

Spectral Optimization of White LED Based on Mesopic Luminance and Color Gamut Volume for Dim Lighting Conditions

Sun

Huang

et al. 2020

Applied Sciences

View full text Add to dashboard Cite

The study aims to propose an approach of white LED spectral optimization based on mesopic luminance and color gamut volume for dim lighting conditions. Three optimal white LED spectra with relatively higher mesopic luminance and color gamut volume, the highest mesopic luminance, and the largest gamut volume are recommended for reducing energy consumption and enhancing color perception and recognition of human eyes. The theoretical simulation shows that the spectra with higher correlated color temperatures (CCT) and S/P-ratio increase the mesopic luminance and also extend the range of color gamut with the decreasing of lighting level. An evaluation model is developed to faster predict mesopic luminance, color gamut volume, and S/P ratio for lighting applications.

show abstract

Calculation of Mesopic Luminance Using per Pixel S/P Ratios Measured with Digital Imaging

Abstract: This study describes a method of measuring the pixelwise S/P ratio using a calibrated digital camera and applying these S/P ratios to calculate mesopic luminance values. An example of using the developed method is presented. Further improvements for the method are discussed.

Cited by 7 publications

References 33 publications

Magnitude to luminance conversions and visual brightness of the night sky

Magnitude to luminance conversions and visual brightness of the night sky

Can we illuminate our cities and (still) see the stars?

Spectral Optimization of White LED Based on Mesopic Luminance and Color Gamut Volume for Dim Lighting Conditions

Contact Info

Product

Resources

About