Method for generating image data of an object under examination, projection data processing device, X-ray system and computer program The invention relates to a method for generating image data (BD) of an object under examination (0) from X-ray projection data (P) of the object under examination (0), wherein, before a reconstruction of the image data (BD), the X-ray projection data (P) are subjected to scattered radiation correction on the basis of scattered radiation measured values. Here, the scattered radiation measured values are initially subjected to an extra-focal radiation correction before being used for the scattered radiation correction. The invention also relates to a projection data processing device (C20) for carrying out a method of this kind and an X-ray system (C1), in particular computed tomography system (C1), with a projection data processing device (C20) of this kind.