Most species of bees, like humans, have trichromatic colour vision and excellent colour discrimination abilities. They acquire visual information through three types of photoreceptors, with peak sensitivities in the short- (UV), medium- (blue) and long-wavelength (green) regions of their visual spectrum. In contrast to us, bees can see UV light but not far red.

This project, produced by the Bee Sensory and Behavioural Ecology Lab, Queen Mary University of London, estimates the electrical signals the bees' photoreceptors will produce in response to an image. The normalized (and so dimensionless) receptor response is the function of the reflectance properties of the stimulus, the spectral sensitivity of the receptor, the illuminant, and the background that the receptor is adapted to. These calculations are described in detail in the related publication [1]. The functions in the program are discretized and can be run at any resolution.

The downloadable zip file below contains the Python script, and a set of example input files. For more multispectral images, visit the Floral Image Database; for a collection of single spectrum measurements, see the Floral Reflectance Database (FReD).

Bee photoreceptor response model (

Arnica Mollis - UV responseArnica Mollis - blue responseArnica Mollis - green response
Example heatmaps for the UV, blue and green photoreceptor responses.


[1] Vasas V, Hanley D, Kevan P, Chittka L (2017) Multispectral images of flowers reveal the adaptive significance of using long-wavelength-sensitive receptors for edge detection in bees. J Comp Physiol A, doi:10.1007/s00359-017-1156-x

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