Meaning of halation

ha•la•tion

Pronunciation: (hā-lā'shun, ha-), [key]
— n. Photog.
  1. a blurred effect around the edges of highlight areas in a photographic image caused by reflection and scattering of light through the emulsion from the back surface of the film support or plate.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.