kromatisering

Kromatisering is a term used in optics and photography to describe the phenomenon of chromatic aberration. Chromatic aberration occurs when a lens, particularly a simple convex lens, is unable to focus all wavelengths of visible light to the same point. This is because the refractive index of the lens material varies slightly with the wavelength of light. Shorter wavelengths, like blue light, are refracted more strongly than longer wavelengths, like red light. As a result, different colors of light are brought to focus at slightly different distances from the lens. This leads to a visible fringing of colors, especially around high-contrast edges in an image.

In photography, kromatisering can manifest as purple or blue halos around bright objects against a dark background, or as red and green fringes around dark objects against a bright background. While early photographic lenses suffered significantly from this aberration, modern lens designs often employ multiple elements made of different types of glass to correct for kromatisering. These achromatic or apochromatic lens designs combine different refractive indices and dispersion properties to bring most, if not all, wavelengths of light to a common focus. Post-processing software also offers tools to reduce or eliminate chromatic aberration in digital images.