Sech central surface brightness μ_0SK of the SF dwarfs as a function of sech absolute magnitude M_SK. The dashed line represents the fit of most dIs and BCDs in the LV and Virgo cluster (Vaduvescu et al. 2006). Most galaxies in A1367, Hercules and Coma show fainter cores compared to galaxies in other clusters with similar luminosity, and the environmental influences could be the origin of these differences. The cross in the upper left shows typical uncertainties in the two parameters.