Abstract: An image sensor provided with a pixel including a photosensitive region formed in a semiconductor substrate and surrounded by a peripheral isolation trench; a sense node formed on a charge collecting region; a charge transfer gate around the sense node; a well; the pixel being provided with a so-called “detection acceleration” transistor configured to, during a so-called “charge overflow detection” operation, be switched on so as to weaken a potential barrier generated by the transfer gate and thus to favour an overflow of photogenerated charges to the sense node of the photosensitive region and to accelerate detection of this overflow.