Figure 2.

Interactions between hue and saturation. Black and white curves show the chromaticity coordinates (first column) and CIELAB coordinates (second column) for the red (a–b), yellow–green (c–d), green–blue (e–f), and blue–purple (g–h) stimulus sets (cf. Table A1). Chromaticity coordinates for the Munsell chips correspond to standard illuminant C (white disc). Grey curves show different levels of Munsell chroma for constant Munsell hues and illustrate the Abney effect. Coloured discs indicate which colour observers would choose as the prototype and unique hue if their choices were affected by saturation. For prototype and unique hue choices, these predictions clearly held.