purple fringing

A bluish-purple, ghost-like color that outlines dark edges of objects such as brown or black hair in a photograph. It tends to be more visible when a wide angle lens is used and when shooting high-contrast images, especially with inexpensive cameras. It may be due to chromatic aberration, lens flare or overexposure. See chromatic aberration and lens flare.

With digital cameras, software idiosyncrasies and sensor abnormalities may cause purple fringing. It is an unwanted side effect of "filling in the blanks" via processing of the image. In all digital cameras, except those that use Foveon's X3 chip, all colors are not stored for each pixel, and the missing colors have to be created by software. See Bayer pattern and X3.