Fig. 3.

Observed microscopic colour patterns. a Light micrograph of rainbow patterned M. robinsoni scales. Black centre square: 4 × 4 μm². b Reflectance spectra collected by hyperspectral imaging of the iridescent scales. c SEM micrograph of the 3D printed foil grating (left, scale bar: 10 μm), and a hyperspectral image of the 3D printed foil grating (right) showing arbitrarily assigned, false-colour rainbow patterns emerging from the tip of the foil grating. Pixels show the same false-colour have the same reflectance spectrum and vice versa. d Reflectance spectra collected by hyperspectral imaging from the entire 3D printed foil grating image. For b, d the colours of the curves are estimated based on the “spec2rgb” function in R script “pavo”⁴⁹