subtraction

The passage around this formula

An event camera, more precisely a dynamic vision sensor (DVS), inverts that design at the pixel level. Each pixel contains its own small analog circuit — a photoreceptor, a differencing amplifier, and a pair of comparators — that continuously tracks the logarithm of local light intensity and fires an asynchronous digital event only when that log-intensity has moved by more than a threshold since the pixel’s last event. Formally, a pixel emits an event when $\left|\log I(t) - \log I(t_{\text{last event}})\right| \geq C$. where C is a contrast threshold set by an analog bias current, and each event carries just an address, a timestamp, and a sign — brighter or darker — streamed out asynchronously on a shared digital bus rather than…

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