Figure 2.
(a) Operation of Darg2 on a countershaded cylinder. Column A: a smooth cylinder under top lighting. Column B: the countershaded cylinder under ambient lighting. Column C: the countershaded cylinder under top lighting. The countershaded cylinder can barely be noted under top lighting, due to the camouflage. Under top lighting, the response of Darg is much stronger when the cylinder is smooth than when it is countershaded, showing that this type of camouflage is effective against Darg. (b) Cross sections (parallel to the y-axis, at the centre of the image) of (i) the intensity functions. Thayer's countershading yields a flat intensity function for a cylinder. (ii) Darg2. Dashed curve, column A; dotted curve, column B; solid curve, column A. Under top lighting, the flattened intensity function of the countershaded cylinder has a lower Darg response than that of the convex intensity function of the smooth cylinder.