Symbol b

The passage around this formula

Commercial event sensors have reached production stacked-silicon form. The Sony-Prophesee IMX636 reports pixel latency under 100 microseconds at 1,000 lux, standby power of 5 milliwatts against a maximum of 205 milliwatts, and a peak event rate above one billion events per second across its 1,280-by-720 array [ 13 ] . Because a pixel only ever transmits when it individually crosses its change threshold, the sensor’s data rate scales with how much of the scene is actually changing, not with the pixel count or a fixed frame clock — the opposite dependency from a frame sensor’s fixed-rate readout: $R_{\mathrm{frame}} = N_{\mathrm{pixels}} \cdot f_{\mathrm{frame}} \cdot b, \qquad R_{\mathrm{event}}(t) \approx N_{\mathrm{active}}(t) \cdot b_{\mathrm{event}}$. where $N_{\mathrm{active}}(t)$ , the number of pixels crossing threshold at a…

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