Abstract: An electromagnetic-radiation detection system is equipped with an electromagnetic-radiation sensor, which has a plurality of detectors sensitive to electromagnetic radiation, allowing images composed of pixels to be obtained, each pixel being represented by at least one value issuing from at least one detector of the sensor. These sensors should generally be cooled. Because of dispersion of the individual responses of each detector of a sensor, each detector of said sensor is calibrated for gain and offset value. A calibration of a detector includes acquiring at least two values issuing from said detector in order to estimate a gain and an offset value to be applied to the values issuing from said detector. A bandpass electromagnetic-radiation filter may have a predefined transmission coefficient in said system in order to vary the electromagnetic radiation reaching said sensor and thus to obtain, for each detector, the two values necessary for implementing calibration.