Red/green opponent colors equilibria measured on chromatic adapting fields: Evidence for gain changes and restoring forces

The luminance invariance and additivity of red/green opponent equilibria were tested under conditions of chromatic adaptation. Four empirical relationships were found. (1) At high test intensities on all adapting fields luminance invariance holds. (2) Luminance invariance holds for all test intensities measured when the adapting field is in red/green equilibrium. (3) At high test intensities on all adapting fields additivity of red/green equilibria holds. (4) At low test intensities on non-equilibrium adapting fields luminance invariance fails. These empirical findings can be explained in terms of a two process model of chromatic adaptation.