The implementation of a Depleted Field Effect Transistor (DEPFET) in each pixel of the DSSC (DEPFET Sensor with Signal Compression) X-ray camera for the European XFEL is intended to provide the appropriate signal compression at high injection levels and low noise figure. The aim of this work is the assessment of the non-linear DEPFET response. To this purpose the response of DSSC DEPFET pixels has been measured and analyzed up to 2 MeV equivalent deposited energy in the experimental conditions foreseen for the final DSSC camera. An appropriate fitting function has been introduced to predict the compression “kink” positions and to model the shape of the compression curve. The preliminary results of this study will be summarized.