Camouflage images

Figure 1: Two camouflage images produced by our technique. The left and right images have seven and four camouflaged objects, respectively, at various levels of difficulty. By removing distinguishable elements from the camouflaged objects we make feature search difficult, forcing the viewers to use conjunction search, a serial and delayed procedure. (Please zoom in for a better effect. Answer keys are on the last page.) Camouflage images contain one or more hidden figures that remain imperceptible or unnoticed for a while. In one possible explanation, the ability to delay the perception of the hidden figures is attributed to the theory that human perception works in two main phases: fea-ture search and conjunction search. Effective camouflage images make feature based recognition difficult, and thus force the recog-nition process to employ conjunction search, which takes consid-erable effort and time. In this paper, we present a technique for creating camouflage images. To foil the feature search, we remove the original subtle texture details of the hidden figures and replace them by that of the surrounding apparent image. To leave an ap-propriate degree of clues for the conjunction search, we compute and assign new tones to regions in the embedded figures by per-forming an optimization between two conflicting terms, which we call immersion and standout, corresponding to hiding and leaving clues, respectively. We show a large number of camouflage images generated by our technique, with or without user guidance. We have tested the quality of the images in an extensive user study, showing a good control of the difficulty levels.