Agent (I) for coloring and/or brightening keratin fibers, preferably human hairs comprises valine (0.05-10 wt.%) and 0.01-10 wt.% of chitosan and/or its derivatives. An independent claim is included for a process for coloring and/or brightening of keratin fibers comprising applying a pretreating agent M1 on the fiber, applying a tinting agent or a coloring agent M2 on the fiber, where the agent M2 is added before the use of a further agent M3, washing the fibers after applying the agent M2, after 5-45 minutes, optionally applying an agent M4 on the fiber and washing the agent after an influential time of some minutes, where at least one of the agent M1, M2 or M3 is (I).
