Figure 11
From: Correlated color temperature is not a suitable proxy for the biological potency of light
The thick black line shows the four-parameter logistic function that determines Circadian Stimulus (CS) from Circadian Light (CLA). The dashed curve indicates the difference in CS when CLA is doubled. This can be thought of the “strength” of doubling CLA on CS at the specified CLA value. The vertical dashed line indicates that the largest increase on CS of doubling CLA occurs at a CLA of 300 (near the inflection point of the logistic function), which can be for a photopic illuminance of 300–500 lx, depending on spectrum.
