Photo Manipulation and Ethics.

The article goes over and shows examples of when editing with photoshop can go to far, even when its not intentional. It shows the difference between carelessly affecting and altering a photo out of reality vs purposely changing a photo to lie.

Photo editing can be either ethical or unethical, there isn't really ground between the two. 

I would say its ethical if its not changing the photo in a way that harms or can change the message of the photo. That is the true purpose of a photo after all, is to tell a story, so if its altered and made false, then its not ethical, its not real anymore. 

The Most Unethical Photo:

August 26, 1989: TV Guide pastes Oprah's head onto Ann Margaret's body

Its quite obvious why this is unethical, nothing about this photo is real! They literally superimposed Oprahs face onto someone else's body, who does that?

The Most Ethical Photo:

May 1970: Pulitzer Prize-winning photo by John Filo shows Mary Ann Vecchio screaming as she kneels over the body of student Jeffrey Miller at Kent State University on May 4, 1970 -- after being fired upon by National Guardsmen.Valley Daily News, 1970 (bottom)
Life Magazine, May 1995 (top)

Out of all the photo shown on the website I would say this is the most ethical because nothing is added or removed from the photo and it still tells the same story. Even though the content of the photo is quite sad, the only thing changed were the levels of white and black color in the photo.