Method and apparatus for the correction of a non-uniform sensitivity of detector elements in thermographic cameras in which background frames of an internal reference are recorded in shutter phases when the beam path of the thermographic camera is closed, the variations between the background frames of the shutter phases are logged, and an updated background frame is generated and used for the correction of at least one image frame, characterized in that the updated background frame is generated from at least one newly recorded background frame and a background frame to be updated in that the data of every pixel of the newly recorded background frame are multiplied by a first factor and are added to the data of every pixel of the background frame to be updated which are multiplied by a second factor, wherein the first factor is a value between zero and one, and the second factor is the difference between one and the first factor, so that the data of every pixel of the updated background frame are in the form of an accumulated weighted average.