Perylene derivatives of the general formula I ##STR00001## where X and Y are independently oxygen, --NR.sup.1 or --NR.sup.2; R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1 C.sub.18-alkyl, C.sub.5 C.sub.7-cycloalkyl, aryl or C.sub.1 C.sub.6-alkoxy; R.sup.3 to R.sup.10 are independently hydrogen, hydroxyl or aryl, although radicals conjointly attached to one carbon atom may also be .dbd.O or .dbd.CHR.sup.11, R.sup.11 is hydrogen or C.sub.1 C.sub.3-alkyl, with the proviso that said perylene derivative I contains from at least one to not more than three carbonyl groups per molecule.