In order to improve the noise suppression in a video image stream 3 of a medical image recording system, the video image stream including a sequence of frames, it is provided that an image processing unit 5 of the image recording system analyses the video image stream 3 continuously in real time and determines at least one variability between successive image pixels of the frames, for example of spatially adjacent image pixels of frames and/or of image pixels of a plurality of the frames corresponding to one another spatially and temporally, in order, on the basis of the variability determined, to set at least one parameter of a noise suppression subsequently applied to the video image stream 3. As a result, the noise suppression can be adapted continuously to a current recording situation.