Measured and Observed Discrepancies of Screen Luminances

Abstract

Some of the reasons for discrepancies between observed and measured luminances of theater screens have been investigated. The resultant spectral distribution is obtained by using a typical coated lamphouse reflector with a carbon-arc or xenon light source that is then combined with the spectral response of the eye and of photometric instruments. The data presented suggest that photometric instruments might be modified to have a mesopic sensitivity to more closely match the spectral response of a partially dark-adapted eye of an observer in a theater. An additional Helmholtz Kohlrausch effect also tends to make xenon screens appear brighter.