Color opponent mechanism

Figure 2.7 Three color opponent mechanisms. The first is an achromatic channel. The second compares the red and green channels. The third compares yellow and blue. The connection to the blue cones in the achromatic, as well as the red-green channel, is drawn with a dotted line as the role of the blue cones is unclear. (Cone illustration from from LifeART Collection Images 1989-2001 by Lippincott Williams Wilkins, used by permission from SmartDraw.com.)...

Figure 2.20 The transformation performed by the color opponency mechanism may be a simple rotation of the coordinate system. In this case, the mechanism for color constancy may operate on the rotated coordinates. (Reprinted from Vision Res., Vol. 26, No. 1, Edwin H. Land, Recent advances in retinex theory, pp. 7-21, Copyright 1986, with permission from Elsevier.)...

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