A System for image processing, comprising an input interface (IN) for receiving energy resolved count data generated by a photon-counting detector (PCD) with at least 2 energy bin but preferable more than two. A count data transformer (DT) of the system is configured to perform a transformation operation to transform the energy resolved count data into transformed count data, the operation including applying one or more weights to the count data, the weights previously obtained based on i) calibration image data for the or a photon-counting detector and ii) calibration image data for an energy integrating detector. A data convertor component (CC) is configured to convert the transformed count data into through-material path length data. The system allows emulating an energy integrating detector.