Photometry in the dark: time dependent visibility of low intensity light sources: erratum

Dirk Poelman; Philippe F. Smet

doi:10.1364/OE.19.018808

Abstract

An error was made in the equations describing the wavelength dependent dark adaptation of the human eye. The conclusions of the paper remain unchanged.

In paper [1], a visibility index is described as:

VI (I (λ), t) = X \times \frac{P}{{PT}_{I (λ)} (t)} + (1 - X) \times \frac{S}{{ST}_{I (λ)} (t)}

where PT _I(λ) (t) and ST _I(λ) (t) are the time dependent visibility thresholds for cones and rods respectively. These curves for the dark adaptation, measured at 460 nm [2] are generalised for an arbitrary spectrum in Eqs. (12) and (13) of the appendix. As the thresholds were measured in photopic units, the photopic threshold is independent of the spectrum used, and Eq. (12) should be replaced by:

{PT}_{I (λ)} (t) = {PT}_{460} (t)

The rod threshold was also measured in photopic units, while the S in Eq. (7) is expressed as scotopic luminance. Therefore, the rod threshold should be converted to the same scotopic luminance, and Eq. (13) should be changed to:

{ST}_{I (λ)} (t) = {ST}_{460} (t) \times \frac{{K'}_{m} \cdot V' (460 nm)}{K_{m} \cdot V (460 nm)} = {ST}_{460} (t) \times 22.56

Figure 4 should also be corrected. The conclusions of the paper are not influenced by these corrections.

Fig. 1 Reference [1], corrected Fig. 4.

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Acknowledgments

Katrien Meert is gratefully acknowledged for pointing out this error.

References and links

1. D. Poelman and P. F. Smet, “Photometry in the dark: time dependent visibility of low intensity light sources,” Opt. Express 18(25), 26293–26299 (2010). [CrossRef] [PubMed]

2. H. Davson, The Eye (Academic Press, 1962), Vol. 2.

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Figures (1)

Fig. 1

Fig. 1 Reference [1], corrected Fig. 4.

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Equations (3)

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VI (I (λ), t) = X \times \frac{P}{{PT}_{I (λ)} (t)} + (1 - X) \times \frac{S}{{ST}_{I (λ)} (t)}

{PT}_{I (λ)} (t) = {PT}_{460} (t)

{ST}_{I (λ)} (t) = {ST}_{460} (t) \times \frac{{K'}_{m} \cdot V' (460 nm)}{K_{m} \cdot V (460 nm)} = {ST}_{460} (t) \times 22.56