A gauge invariant effective Lagrangian with ten anomalous gauge boson couplings
is considered. Sensitivities on these couplings are discussed for the process
gamma gamma -> W+ W-, both for the LHC and the ILC. Statistically optimal
observables are used to disentangle the different anomalous contributions to
the normalised event distributions. The measurements of photon-photon processes
are shown to complement the observables for e+e- collisions.