It's commonly known that natural daylight is the only light source that will not distort our ability to evaluate color. Any well-managed color program specifies a form of daylight as the light source of choice for making accurate color evaluations.
The problem with natural daylight is that its appearance and spectral characteristics can change dramatically from day to day, season to season and even during a single day. Morning sunrise tends to have a red hue. An overcast day appears gray and drab, and a crystal clear bright sky appears blue. Changes in daylight quality are affected by atmospheric conditions, the change of seasons, time of day, pollution, altitude and even your location – city versus country. All of these factors affect our ability to accurately evaluate the color quality of a product, hence the need for daylight simulation.
This paper dispels the common myths and misconceptions about daylight simulators. It reviews technologies, industry standards and practices, and issues relative to simulating daylight in color evaluation applications.