June 2007
Volume 7, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2007
Vµ*(λ): a generalized luminous efficiency function for any condition of chromatic adaptation
Author Affiliations
  • Andrew Stockman
    Institute of Ophthalmology, University College London, UK
  • Herbert Jägle
    Division of Experimental Ophthalmology, University Eye Clinic, Tübingen, Germany
  • Markus Pirzer
    Division of Experimental Ophthalmology, University Eye Clinic, Tübingen, Germany
  • Lindsay Sharpe
    Institute of Ophthalmology, University College London, UK.
Journal of Vision June 2007, Vol.7, 793. doi:10.1167/7.9.793
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      Andrew Stockman, Herbert Jägle, Markus Pirzer, Lindsay Sharpe; Vµ*(λ): a generalized luminous efficiency function for any condition of chromatic adaptation. Journal of Vision 2007;7(9):793. doi: 10.1167/7.9.793.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Introduction: We recently proposed a luminous efficiency function, V*(λ), for 2° photopic viewing based on heterochromatic flicker photometric (HFP) measurements made under daylight (D65) adaptation (Sharpe, Stockman, Jagla, & Jägle, 2005). V*(λ), is defined as a linear combination of the Stockman & Sharpe (2000) long-wavelength sensitive (L-) and middle-wavelength sensitive (M-) cone fundamentals. However, the applicability of V*(λ) is limited to its measuring conditions, because the relative contributions of the L- and M-cones to luminous efficiency depend strongly on the state of chromatic adaptation. Here, we extend its applicability by characterizing its dependence on background chromaticity.

Methods: 25 Hz HFP matches were obtained in 6 genotyped male observers on 23 different 3.0 log10 photopic troland adapting fields (µ): 14 spectral ones (µ = 430 to 670 nm); 7 bichromatic mixtures (µ = 478 + 577 nm) that varied in luminance ratio; and 2 corresponding to CIE Illuminants A and D65 daylight. Each of the resulting 23 luminous efficiency functions, Vµ*(λ), was characterized as a best-fitting linear combination of the cone fundamentals, aL(λ) + M(µ), where a, the L-cone weighting factor, varies with µ, the effective background wavelength.

Results: As expected, short-wavelength fields increase a, by decreasing the relative M-cone contribution, and long-wavelength fields decrease a, by decreasing the relative L-cone contribution. However, the changes in a are larger on short wavelengths fields and smaller on long-wavelengths ones than predicted from reciprocal sensitivity adjustment (Weber's Law). Shorter and longer wavelength chromatic fields both relatively suppress the M-cone contribution to Vµ*(λ) in excess of Weber's Law.

Conclusions: Our generalized model accounts for Weber's Law and the chromatic suppression of the M-cone contribution to Vµ*(λ). It allows a(µ), and therefore Vµ*(λ), to be predicted for a standard observer for any chromatic background of 1000 td.

Stockman, A. Jägle, H. Pirzer, M. Sharpe, L. (2007). Vµ*(λ): a generalized luminous efficiency function for any condition of chromatic adaptation [Abstract]. Journal of Vision, 7(9):793, 793a, http://journalofvision.org/7/9/793/, doi:10.1167/7.9.793. [CrossRef]
Footnotes
 Grants: JA997/5-1 to HJ
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