The’Visual Contrast Analysis’ is an umbrella term for a variety of pattern parameters which were first conceptualised by John Endler in the early 90s (Endler 1990, 1991, 1992; Endler & Mielke 2005). These parameters seek to combine both chromatic and achromatic properties of colour pattern elements with their spatial properties, specifically their relative abundance in a given colour pattern to describe the visual contrast (Saliency, vividness, detectability, memorability) a colour pattern might provide to an observer. A range of these parameters have been tested on biological systems such as guppies (Endler & Houde 1995) with many more avaiting testing.
We have taken every possible parameter which has ever been formulated as well as expanding on the existing selection (See here). However, we have systematically excluded angular chromaticity metrics and replaced them with metrics derived from the log-transformed Receptor Noise Limited (RNL) colour space. For detailed information and equations please see the suppl. Material.
References:
Endler, J.A. & Houde, A.E. 1995. Geographic Variation in Female Preferences for Male Traits in Poecilia reticulata. Evolution (N. Y).49: 456–468.
Endler, J.A. 1990. On the measurement and classification of colour in studies of animal colour patterns. Biol. J. Linn. Soc. 41: 315–332.
Endler, J.A. 1992. Signals, signal conditions, and the direction of evolution. Am. Nat. 139.
Endler, J.A. 1991. Variation in the appearance of guppy color patterns to guppies and their predators under different visual conditions. Vision Res. 31: 587–608.
Endler, J.A. & Houde, A.E. 1995. Geographic Variation in Female Preferences for Male Traits in Poecilia reticulata. Evolution (N. Y). 49: 456–468.
Endler, J.A. & Mielke, P.P.W. 2005. Comparing entire colour patterns as birds see them. Biol. J. Linn. Soc. 86: 405–431.