Using stably transfected HeLa cells expressing either green fluorescent protein (GFP) labelled histone H2B or yellow fluorescent protein (YFP) labelled histone H2A, we investigated the positioning of individual histone proteins in cell nuclei by means of high resolution localization microscopy (Spectral Position Determination Microscopy = SPDM). The cells were exposed to ionizing radiation of different doses and aliquots were fixed after different repair times for SPDM imaging. In addition to the repair dependent histone protein pattern, the positioning of antibodies specific for heterochromatin and euchromatin was recorded by SPDM. Experimental data was acquired in the Experimental Biophysics group by Michael Hausmann, Patrick Müller, Sabina Hillebrandt, Margund Bach and Rainer Kaufmann. Kernel Density Estimations of the experimental data and the maskings of the regions of interest based on the KDEs were calculated by Yang Zhang, a member of the Statistical Physics and Theoretical Biophysics Group.