Controlling object appearance with variable spectral distribution of lighting having constant chromaticity

A lighting system, comprising:

• a plurality of output channels each configured to provide power to a light source;
• and
• a controller configured to individually control the output channels, wherein the control includes activating a first one of the output channels to illuminate a given target with a first light source having a first chromaticity so as to cause the target to have a first appearance, and activating a second one of the output channels to illuminate the target with a second light source having a second chromaticity so as to cause the target to have a second appearance, wherein the second chromaticity is within a MacAdam ellipse having the first chromaticity;
• wherein the MacAdam ellipse is a 7-step MacAdam ellipse or smaller.

A lighting system, comprising:

• a target to be illuminated;
• a plurality of light sources including a first light source having a first chromaticity and a second light source having a second chromaticity, wherein the second chromaticity is within a 3-step MacAdam ellipse having the first chromaticity;
• a plurality of output channels each configured to provide power to a corresponding one of the light sources;
• and
• a controller configured to individually control the output channels, wherein the control includes activating a first one of the output channels to illuminate the target with the first light source so as to cause the target to have a first appearance, and activating a second one of the output channels to illuminate the target with the second light source so as to cause the target to have a second appearance;
• wherein one of the first or second light sources includes a spectral feature not included in the other light source, and an optical response property of the target reacts to changes in the spectral feature thereby causing changes in appearance.