RNLthres {colourvision} | R Documentation |

Colour thresholds based on receptor noise for any number of photoreceptor types (Vorobyev & Osorio 1998).

RNLthres(photo=ncol(C)-1, Rb, I, C, noise=TRUE, v=NA, n=NA, e=NA, interpolate=TRUE, nm=seq(300,700,1))

`photo` |
Number of photoreceptor types. Model accepts any number of photoreceptor types ( |

`Rb` |
Background reflectance. A data frame with two columns only: first column corresponding to wavelength values and second column with reflectance values. |

`I` |
Irradiance spectrum. A data frame with two columns only: first column corresponding to wavelength values and second column with irradiance values. Irradiance values must be in quantum flux units. |

`C` |
Photoreceptor sensitivity curves, from lowest to longest lambda-max. A data frame: first column corresponding to wavelength values and following columns with photoreceptor sensitivity values (see function |

`noise` |
Logical. Whether receptor noise is provided ( |

`e` |
Receptor noise of each photoreceptor type. Used when |

`n` |
Relative number of each photoreceptor type in the retina. Usually increases with lambda-max. Used to calculate |

`v` |
Noise-to-signal ratio of a single photoreceptor. Used to calculate |

`interpolate` |
Whether data files should be interpolated before further calculations. See |

`nm` |
A sequence of numeric values specifying where interpolation is to take place. See |

Colour thresholds based on receptor noise limited model as in Vorobyev and Osorio (1998). In lack of a direct measurement, receptor noise (*ei*) can be estimated by the relative abundance of photoreceptor types in the retina, and a measurement of a single photoreceptor noise-to-signal ratio:

*ei=v/sqrt(n)*

where *v* is the noise-to-signal ratio of a single photoreceptor, and *n* is the relative abundance of photoreceptor i in the retina. Alternatively, noise may be dependent of the intensity, but this possibility is not implement in `colourvision`

yet. Noise dependent of intensity usually holds for low light conditions only (Vorobyev et al. 1998).

A data.frame with the following columns:

`nm` |
Wavelength in nm. |

`T` |
Colour threshold value. |

`S` |
Log of sensitivity value (inverse of threshold). |

Felipe M. Gawryszewski f.gawry@gmail.com

Vorobyev, M., and D. Osorio. 1998. Receptor noise as a determinant of colour thresholds. Proceedings of the Royal Society B 265:351-358.

###Bee photoreceptors normalized to max=1. data("bee") C<-bee C[,2]<-C[,2]/max(C[,2]) C[,3]<-C[,3]/max(C[,3]) C[,4]<-C[,4]/max(C[,4]) ##Grey background: Rb <- data.frame(300:700, rep(0.1, length(300:700))) ## CIE D65 illuminant: data("D65") #Thresholds thres<-RNLthres(photo=3, Rb=Rb, I=D65, C=C, noise=TRUE, e = c(0.13, 0.06, 0.12)) plot(thres)

[Package *colourvision* version 2.0.3 Index]