colorshifting

Colorshifting refers to the visible change in hue when the viewer's perspective or lighting changes. It arises from angle-dependent optical interactions that selectively reflect, transmit, or scatter different wavelengths.

Mechanisms include structural coloration via thin-film interference in multilayer coatings or in natural structures; diffraction from periodic surfaces; scattering in certain pigments; and liquid crystal or metamaterial effects where the refractive index experienced by light changes with orientation. Pigment arrangements can also produce angle-dependent reflections, contributing to color shifts.

Materials and examples include automotive color-shift paints employing multilayer dielectric stacks that reflect different wavelengths at different angles; pearlescent pigments based on mica platelets with metal oxide coatings; opal-like nanostructured materials; and photonic crystals.

Applications encompass security printing (color-shifting inks on money and documents), cosmetics and fashion, art, camouflage, and sensing. Color shifting can enhance visual effects or provide functional cues in design and technology.

Limitations involve shifts that may be narrowband or limited to a specific viewing angle range; lighting conditions strongly influence perceived color; and practical considerations such as durability, cost, and color consistency can constrain use. See also iridescence, pearlescent pigments, structural color, and interference coating.