|Colored lithograph from La Guerre Documentée|
To my mind, this is one of the most exquisite illustrations of camouflage, as practiced during World War I. It's one of a series of colored lithographs that appeared initially in La Guerre Documentée (c1920).
It represents three stages in the application of disruptive camouflage. In the top, there is no disruption since the truck is painted in monochrome gray (in a manner not unlike the use of battleship gray in ship camouflage). In the second stage, disruptive shapes have been applied that contradict its physical shape. And then, in the bottom image, the truck has been placed in a setting in which it is not only visually broken apart (high difference) but aspects of its pattern blend (high similarity) with various parts of the background.
The gestalt psychologists' term for this was an embedded figure. In his famous book, Adaptive Coloration in Animals (1940), British zoologist (and military camouflage instructor) Hugh B. Cott talked about the combined use of blending and disruption in the coloration of animals, as when a frog folds up its legs, and connecting patterns link its limbs. Much earlier, American artist Abbott H. Thayer had described the same phenomenon (in Concealing Coloration in the Animal Kingdom (1909)), but it was Cott who came up with a suitable name—he called it coincident disruption.