Population gradients and photometric metallicities in early- and transition-type dwarf galaxies: Clues from the Sculptor groupS. Lianou, E. K. Grebel, G. S. Da Costa, M. Rejkuba, H. Jerjen and A. KochA&A, 550 (2013) A7DOI: https://doi.org/10.1051/0004-6361/201219959