Face recognition at mesopic light levels and various light spectra
conference paper
Light sources that are optimized for mesopic vision contain a relatively high amount of bluish light (high S/P-ratio) and are therefore effective for peripheral visual tasks at mesopic light levels. Since the spectra of these light sources differ strongly from the common public lighting there were doubts on the performance of these light sources in residential areas where faces of pedestrians should be recognised at sufficient distance. We performed a face recognition experiment at mesopic light levels using light sources with six various light spectra and S/P-ratios between 0.52 and 3.16. We measured the vertical and semi-cylindrical photopic illuminance at the faces of the target persons. The mesopic illuminance was calculated with the CIE-191 model. It appeared that the face recognition distance strongly depends on the vertical photopic illuminance at the face of the target persons but no difference was found between the six light spectra. The mesopic and semi-cylindrical illuminance did not give a better prediction of the face recognition distance than the common vertical photopic illuminance. The experiment indicates that the spectrum of the lamps is not very important for face recognition, which is a foveal visual task where only the central part of the visual field is involved and where the mesopic effect does not play a role.
TNO Identifier
478881
Source title
Proceedings of the 12th European Lighting Conference Lux Europa 2013, 17-19 September 2013, Kraków, Poland
Pages
212-217
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