What is CIE's Recommended System for Mesopic Photometry?(<Special Issue>Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

This article introduces the CIE191:2010 Recommended System for Mesopic Photometry Based on Visual Performance. This article will lead readers to understand how to calculate a mesopic luminance by using two variables, i.e., an s/p ratio and an adaptation luminance, what kinds of experimental data CIE191 was based on, and what problems CIE191 has to be solved before being applied to practical lighting applications.