Camouflage the peacock flounder, squid and octopus actively change their skin patterns and colours using special chromatophore cells to resemble their current background, or, as in most chameleons, for signalling. However, Smith's dwarf chameleon does use active colour change for camouflage. Each chromatophore contains pigment of only one colour. In fish and frogs, colour change is mediated by the type of chromatophores known as melanophores that contain dark pigment. A melanophore is star-shaped; it contains many small pigmented organelles which can be dispersed throughout the cell, or aggregated near its centre. When the pigmented organelles are dispersed, the cell makes a
Multi-scale camouflage and overall disruptive effect. A failure to consider all elements of pattern design tends to result in poor results. The US Army's Universal Camouflage Pattern (UCP), for example, adopted after limited testing in 2003–4, performed poorly because of low pattern contrast ("isoluminance"—beyond very close range, the design looks like a field of solid light grey, failing to disrupt an object's outlines) and arbitrary colour selection, neither of which could be saved by quantizing (digitizing) the pattern geometry. The design was replaced from 2015 with Operational Camouflage Pattern, a non-pixellated pattern. The idea of patterned camouflage extends back to the interwar