Almost complete colour constancy achieved with full-field adaptation

A successive asymmetric colour-matching task was used to study the changes in colour appearance of simulated Munsell samples. Colour shifts were induced with two Planckian illuminants, standard illuminant A (u′ = 0.256, v′ = 0.524) and illuminant S (u′ = 0.174, v′ = 0.392). Measurements were conducted with a 20° field and a 120° field. Adaptation period varied from 1 to 30 s with the smaller field and from 1 to 60 s with the larger field. Colour shifts were specified in terms of a modified Brunswik ratio (BR). Higher values of BR were associated with longer adaptation periods but only when the larger background was used. Supplementary experiments showed that the changes in colour appearance were related to a slight shift in the perceived colour of the background. The timing of the colour shifts are modelled in terms of cone opponent responses. High values of BR correspond to almost complete von Kries adaptation in all three cone types.