“…There are many approaches [30,31] for estimating the temporal delay, δ pq , between two time series, I(p, t) and I(q, t). We compute the delay using a two-stage process, first described by Workman et al [21]. To initialize, we select the integer delay offset that maximizes the correlation between the two time series (in our implementation we use the time series of the green color channel, because it had less spatial noise than the intensity in the videos we use for evaluation).…”