Flicker Index (FI)
Flicker Index (FI) is a measure of ripple based on the determination of integrals under the curve. Unlike the previous measure, the flicker index takes into account the shape and filling of the waveform in addition to its amplitude. The value of the measure can range from 0 (in the absence of ripple) to 1. The U.S. IES recommends that light sources should not exceed flicker index=0.1.
A - area under the curve to the level of the
B - area under the curve from the level of the
average to zero.