Photo Manipulation, how far can you go?

It would be easy for a magazine editor to forbid photo manipulation. But as soon as red eye is removed from someone's photo, the image is altered.
Readers will accept fixing flaws, such as correcting colors or lighting. After all, that's what most of them do with their personal photographs before they have them printed.Shooting in black and white or changing a color photo to appear black and white is technically manipulating reality. Because no deception is involved, this creative technique will not raise ethical concerns

Removing food particles or improving smiles may be performed with the best of intentions, but sometimes photos are enhanced for more questionable motives. Time and Newsweek had another cover shot faceoff when O.J. Simpson was arrested in 1994.
Both magazines used his mug shot on their covers. But the Time photo showed Simpson's skin noticeably darker, which had critics saying that the magazine wanted him to appear more sinister. Some even said racial bias was behind the change. Skin tone is a touchy issue for media critics. Beyonce Knowles was blasted for appearing in a fashion shoot with lighter skin, while ESPN The Magazine was booed when it demonstrated how NFL quarterback Michael Vick might look as a white man.
Source:http://media.about.com/od/printmedia/a/The-Ethics-Of-Magazine-Photo-Manipulation.htm