Above WWII American ship camouflage (unidentified), 1944
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Matthew Luckiesh, Visual illusions, their causes, characteristics and applications. New York: Van Nostrand, 1922, pp. 225-227—
Many optical illusions have been devised and studied by scientists. In fact, some of these tricks are well known to the general reader. Straight lines may appear broken, convergent, or divergent by providing certain patterns or lines intermingled with them. [Beginning in World War I] Many of these were applied to models in laboratory experiments and it has been shown that confusion results as to the course of the vessel. The application of these on vessels has resulted in the grotesque patterns to be seen on ships during the latter stage of the war. It is well known that these illusions are most effective when the greatest contrasts are used, hence black and white patterns are common. Color has not been utilized as definitely as pattern in confusibility, although there is a secondary aim of obtaining low visibility at a great distance by properly balancing the black, white, and other colors so that a blue-gray results at distances too great for the individual patterns to be resolved by the eye. Color could be used for the purpose of increasing the conclusion by apparently altering the perspective. For example, blue and red patterns on the same surface do not usually appear at the same distance, the red appearing closer than the blue.
Such apparently grotesque patterns aimed to distort the lines of the ship and to warp the perspective by which the course is estimated. This was the final type of marine camouflage at the close of the war. Besides relying upon these illusions, ships zigzagged on being attacked and aimed in other ways to confuse the enemy. No general attempt was made to disguise the bow, because the bow-wave was generally visible. However, attempts have been made to increase it apparently and even to provide one at the stern. In fact, ingenuity was heavily drawn upon and many expedients were tried.
