Colour vision models: a practical guide, some simulations, andcolourvisionR package

Abstract

17• Human colour vision differs from the vision of other animals. The most obvious 18 differences are the number and type of photoreceptors in the retina. E.g., while humans are 19 insensitive to ultraviolet (UV) light, most non-mammal vertebrates and insects have a colour 20 vision that spans into the UV. The development of colour vision models allowed appraisals of 21 colour vision independent of the human experience. These models are now widespread in 22 ecology and evolution fields. Here I present a guide to colour vision modelling, run a series of 23 simulations, and provide a R package -colourvision -to facilitate the use of colour vision 24 models. 25• I present the mathematical steps for calculation of the most commonly used colour vision (1998) linear and log-linear receptor noise limited models (RNL). These models are then tested 28 using identical simulated and real data. These comprise of reflectance spectra generated by a 29 logistic function against an achromatic background, achromatic reflectance against an 30 27, 2017; achromatic background, achromatic reflectance against a chromatic background, and real flower 31 reflectance data against a natural background reflectance. 32ND 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/103754 doi: bioRxiv preprint first posted online Jan.• When the specific requirements of each model are met, between model results are, 33 overall, qualitatively and quantitatively similar. However, under many common scenarios of 34 colour measurements, models may generate spurious values and/or considerably different 35 predictions. Models that log-transform data and use relative photoreceptor outputs are prone to 36 generate unrealistic results when the stimulus photon catch is smaller than the background 37 photon catch. Moreover, models may generate unrealistic results when the background is 38 chromatic (e.g. leaf reflectance) and the stimulus is an achromatic low reflectance spectrum. 39• Colour vision models are a valuable tool in several ecology and evolution subfields.

Intrafloral Color Modularity in a Bee-Pollinated Orchid

“…Euclidian color distances between loci is a proxy for chromatic contrast, while the angular distance between loci corresponds to the difference in color hue. We are aware that bees behave differently to colors on different hexagons subsets, in a way that similar Euclidean distances might not elicit similar discrimination responses by bees ( Dyer and Chittka, 2004 ; Telles and Rodríguez-Gironés, 2015 ), yet the bee hexagon color space model is a simple and reliable tool to access the kind of information we are aiming to evaluate in this study ( Gawryszewski, 2017 ).…”