An exposure time controller for controlling an exposure time (ET) variable of a video camera, which is associated with an auto-exposure algorithm configured to reduce an exposure mismatch (ΔE) by incrementing and decrementing the ET variable, which comprises: a memory for recording ET values applied while the video camera is imaging a scene and the algorithm is active; and processing circuitry configured to: determine that the exposure mismatch exceeds a threshold while the video camera is imaging the scene; estimate a distribution of the recorded ET values; based on the estimated distribution, identify multiple relatively most frequent ET values; and, in reaction to determining that the exposure mismatch exceeds the threshold, assign one of the identified ET values to the ET variable.