Simulations of charge summing and threshold dispersion effects in Medipix3

► Medipix3 readout chip compensates charge sharing using inter-pixel communication. ► In initial production run, the flat-field response is unexpectedly nonuniform. ► This effect is reproduced in simulation, and is caused by threshold dispersion. ► A new inter-pixel communication process is proposed. ► Simulations demonstrate the new process should give much better uniformity.