Värivarjostus

Värivarjostus, also known as color shading or chromatic aberration in a visual context, refers to the effect where different colors of light are focused at slightly different points by a lens. This phenomenon occurs because the refractive index of a lens material varies with the wavelength of light. Consequently, when white light passes through a lens, it is dispersed into its constituent colors, similar to a prism.

This dispersion results in chromatic aberration, a type of optical distortion. In imaging, it manifests as colored fringes or halos around objects, particularly noticeable at high contrast edges. For instance, bright objects against a dark background might appear with blue or purple edges on one side and yellow or red edges on the other. This effect is more pronounced with simple lens designs and at the edges of an image.

In photography and optics, efforts are made to minimize värivarjostus. This is typically achieved through the use of achromatic or apochromatic lens systems. These complex lens designs combine multiple lens elements made from different types of glass with varying refractive properties. By carefully selecting and arranging these elements, the chromatic aberration caused by each individual lens can be corrected, bringing different colors of light to a common focal point. While complete elimination is challenging, advanced lens designs can significantly reduce the visual impact of värivarjostus.