The boy at the left has too much light and the boy at the right has Red Eye which are corrected in a rollover effect.

Boy with too much light  Boy with Red Eye

Rollovers were used in the following photos to show various techniques of photo lightening, manipulation, and caricature.

Underexposed Airplane  Mcamaras Family Photo  John Makeover

Lady with Skin so soft  Wrinkles of a lady  Navy Man