Below is a simulated compound-eye view showing how a Great Spangled Fritillary Butterfly sees another Great Spangled Fritillary Butterfly from different distances. The largest image, at top right, is what the butterfly would see at 18 centimeters’ distance. The lower image provides a simulated view at 7 centimeters (left), compared with the original photograph (right). At 18 centimeters a striking phenomenon occurs: If the “eye” or the subject moves slightly, large portions of the field of view seem to flash between all orange and all black. It may be more than coincidence that 18 centimeters (7 inches) is the typical courtship distance for this species. The regularity of the compound eye may act as a cross-correlation filter for the regularity of the spotted wing design.