Method for Quantifying the Spectral Based Error in Luminance Measurements

The accuracy of luminance measurements throughout the visible spectrum was investigated by breaking down a broadband source into narrow bandwidth sections. Measurements from a standard luminance meter were then compared to a derived luminance found with an illuminance spectrophotometer. High Dynamic Range Images (HDRI) of the narrow bandwidth sources were also taken in order to evaluate the spectrally dependent accuracy of HDRI as a luminance measurement tool. These results were evaluated for nine saturated color sources throughout the visible spectrum, as well as a white LED. The saturated sources were expected to produce errors in luminance measurements, based on previous studies. However, results of the white LED condition raised additional concerns about the accuracy of photometric measurements for LED sources. Additional research on how the spectral characteristics of a source affect the accuracy of standard illuminance and luminance meters is also presented in this report.