Brown Belly of the Lizard podarcis tiliguerta
Badiane, A., & Font, E. (2021). Information content of ultraviolet-reflecting colour patches and visual perception of body coloration in the tyrrhenian wall lizard podarcis tiliguerta. Behavioral Ecology and Sociobiology, 75,
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| Originator | Publication |
Here the colour of the object with this reflection spectrum is cacluated. The height of the bars represents the signal seen from each photoreceptor, mathematically: Integral over the product of reflection spectrum and photoreceptor sensitivity. This is euqivalent to a light of constant intensity (pure mathematically white light) being reflected. The cone sensitivites are normalized such that the area under their curve equals 1. This is equivalent to white light of constant intensity resulting in an equal signal to each photoreceptor. For reptiles these four "hypothetical" photoreceptor sensitivites are chosen: L-Cone, M-Cone, S-Cone, and U-Cone. They are based on measured reptile photoreceptor sensitivity curves and chosen as an average over different species. For the human colour vision, a RGB colour approximation for the coordiante is shown as a small square (note that this is only a rough estimate, as converting colour to RGB is more difficult than it seems and I have chosen an easy route).
| Human (CIE) | 3 cone reptile | 4 cone reptile | |
|---|---|---|---|
| Cone Excitation | |||
| Colour Coordinate | ( 0.39 ; 0.4 ) ◼ | ( 0.58 ; 0.33 ) | ( 0.45 ; 0.32 ; 0.18 ) |
| colour space | 3-D-graph not implemented yet |
In this second colour calculation, not a light source with constant spectrum, but with a standard LED spectrum (Spectrum id 722) was chosen as reference. The spectrum graph shows the product spectrum of LED light and reflection spectrum and in green the two indivial spectra. For human colour vision the colour should hardly change. For reptiles with UVA colour vision the missing UVA in the LED makes a drastic difference.
| Human (CIE) | 3 cone reptile | 4 cone reptile | |
|---|---|---|---|
| Cone Excitation | |||
| Colour Coordinate | ( 0.4 ; 0.42 ) ◼ | ( 0.66 ; 0.34 ) | ( 0.53 ; 0.31 ; 0.16 ) |
| colour space | 3-D-graph not implemented yet |