An image sensor comprises an arrangement of pixels, the pixels including an acquisition circuit each, the acquisition circuit including: a sensor circuit configured to generate a sensor signal (VLOG) depending on a light signal illuminating a photosensor of the pixel; a storage circuit configured to store during a storage interval a stored signal (VSTORE) proportional to the sensor signal (VLOG); and a comparator circuit configured to generate after the refresh interval a comparator signal (VCOMP) depending on the sensor signal (VLOG) and the stored signal (VSTORE). A method of operating an image sensor comprises steps of generating a sensor signal (VLOG) depending on a light signal illuminating a photosensor of the pixel, storing during a storage interval a stored signal (VSTORE) proportional to the sensor signal (VLOG) and generating after the refresh interval a comparator signal (VCOMP) depending on the sensor signal (VLOG) and the stored signal (VSTORE).