Vision with isoluminant colour contrast: 1.A projection technique and observations.

An optical technique is described for projecting two-colour pictures with controlled brightness contrast, which may be set to zero-at isoluminance. Colour registration is maintained without adjustment or special setting up. It is suggested that colour-and brightness-contour registration in the visual channel is a problem which may be solved neurally be master brightness signals locking slave colour signals. The projection apparatus allows the supposed master brightness signals to be removed-at isoluminance-when contour disturbances should occur. Observation of this kind are reported.