A method adjusts the sensitivity of an image sensor, and includes: adjusting an integration duration of the image sensor between a minimum duration and an image frame duration, receiving from the image sensor a frame signal, and amplifying the frame signal by applying an adjusted amplification gain between different minimum and maximum gain values. For each frame of the frame signal, if an integration duration, calculated as a function of an average value of the frame signal, is comprised between the minimum duration and a maximum duration equal to several times the frame duration, the method establishes the integration duration at the integration duration calculated and maintains the amplification gain at a fixed value, otherwise it maintains the integration duration at the minimum or maximum duration and adjusts the amplification gain between the minimum and maximum values as a function of the average value.