Differential I magnitudes of EE Cep obtained at Piwnice Observatory during the 13 years from 1996 to 2010. The zero value corresponds to the level of the average brightness outside (phases 0.4–0.8) eclipses. Below +01 (i.e. for magnitude changes smaller than +01) an artificial, strongly non-linear scale is used to reduce the contrast in the amplitude of the changes during and outside eclipses (thus, the relatively small variations outside the eclipses can be seen and compared with the depth of the eclipses).