Classification of peacock feather reflectance using principal component analysis similarity factors from multispectral imaging data

Abstract

Iridescent structural colors in biology exhibit sophisticated spatially-varying reflectance properties that depend on both the illumination and viewing angles. The classification of such spectral and spatial information in iridescent structurally colored surfaces is important to elucidate the functional role of irregularity and to improve understanding of color pattern formation at different length scales. In this study, we propose a non-invasive method for the spectral classification of spatial reflectance patterns at the micron scale based on the multispectral imaging technique and the principal component analysis similarity factor (PCASF). We demonstrate the effectiveness of this approach and its component methods by detailing its use in the study of the angle-dependent reflectance properties of Pavo cristatus (the common peacock) feathers, a species of peafowl very well known to exhibit bright and saturated iridescent colors. We show that multispectral reflectance imaging and PCASF approaches can be used as effective tools for spectral recognition of iridescent patterns in the visible spectrum and provide meaningful information for spectral classification of the irregularity of the microstructure in iridescent plumage.

Regulation of melanocyte stem cells in the pigmentation of skin and its appendages: Biological patterning and therapeutic potentials

“…Structural colour is based on the arrangement of organelles (eg, melanosomes) or cell shapes (eg, barbules). Peacock tail feathers look blue or green based on iridescent and light interference . Another good example is the blackness produced by the tight interwoven of barbules in paradise birds.…”

Biophotonics of diversely coloured peacock tail feathers

“…However, when the melanosome-air-layer stack consists of only a few periods (as in regions 3-6), minor changes in the spacing of the rst layers can cause distinct modulations in the reectance spectra. 28,29 We found that the keratin cortex and the melanosome diameter in the rst lattice periods play a prominent role in adjusting the peak shape. Interestingly, the effect of these peak shape modulating parameters decreases when the number of melanosome layers increases.…”

“…1,4 Subsequent spectrophotometry on peacock tail, neck and shoulder feathers yielded a variety of single-and double-peaked reectance spectra, which were interpreted by various optical methods. [26][27][28][29][30] We recently studied the blue feathers of the peacock's neck and breast, applying spectrophotometry and imaging scatterometry. The measured spectra could be well explained with an effective-medium multilayer model.…”

A fast multispectral light synthesiser based on LEDs and a diffraction grating

“…In colour science, the LED synthesiser can be used as the light source for BRDF (bidirectional reflectance distribution) measurements with an imaging hemispherical scatterometer36, or with an imaging angular reflectometer37. If larger scenes need to be illuminated from several angles, the LEDs and output fibres can be stacked in vertical columns around a single grating, or several LED synthesisers can be operated in synchrony.…”