Fig. 1
From: Melanin-based structural coloration of birds and its biomimetic applications
(a-c) Basic physical mechanisms of structural coloration in birds. Structural colors appeared in barbs or barbules are based on (a) Thin-film interference, (b) Incoherent scattering, (c) Coherent scattering, (d-e) Representative melanin-based photonic nanostructures, (d) Crystalline nanostructures generate iridescent colors, and (e) Amorphous nanostructures generate non-iridescent colors