1. A method for reconstructing image data of an examination subject from measured data, comprising: acquiring a series of measured data sets during a relative rotational movement between a radiation source of a computed tomography system and the examination subject and the measured data sets relate to a same section of the examination subject at succeeding instants in time; reconstructing first image data from each of the measured data sets, such that a series of first image data is available; determining a change variable indicating a change over time within the series of first image data; and distinguishing between different components of the examination subject in the first image data with the aid of the change variable, the distinction being used for beam hardening correction in an iterative algorithm for calculating enhanced image data.