The invention relates to an image sensor comprising a photodetector array including neighboring photodetector elements, each photodetector element comprising: - a photodetector cell having a photodiode and a reset unit; - a cell control unit coupled with the photodetector cell and configured to reset the photodiode by means of the reset unit; wherein the cell control unit is configured to asynchronously effect resetting of the photodiode after a given dead time after detection of a photon.