Figure 4.

Filter responses to a typical pre-egress–egress sequence tracked over a period of 10 s, before and after the egress event. (A) Response of all six tested image filters to an example egress event. The signal strength from each filter is reported relative to the mean noise level for that signal. Image records were taken at 10 frames per second. (B) Selected responses of the three filters with the strongest and most consistent signals. The numbers next to the markers on the steep upward deflection of each trace report the frame number in which each filter first registered a significant egress-related signal; these numbers are shown to illustrate the tight synchronicity of filter detection.