Abstract: The imaging apparatus comprises a detector constituted by a two-dimensional matrix of opto-electronic sensors and by correction means for correcting the output signals in order to compensate for the differences between the response characteristics of the various sensors by applying respective offset values and stored gains thereto. An optical plate is temporarily interposed on the inlet beam, which plate is sufficiently diffusing to make the illumination received from the observed scene uniform over all of the sensors. The offset value for each sensor is calculated from the output signals of the sensors while they receive the uniform illumination, taking the stored gains into account.