You might be interested in this article from New York Times>
Walker Evans. Or Is It?
By MICHAEL KIMMELMAN
Published: August 25, 2006
"....A printer, in a dark room using chemicals, or at a computer
screen, can tinker with the image, crop it, enlarge it, make it
lighter or darker, highlight one part or obscure another.
"In other words, the image produced by the camera, whether it's a
negative or a digital file, is only the matrix for the work of art. It
is not the work itself, although if the photographer is a journalist,
any hanky-panky in the printing process comes at the potential cost of
the picture's integrity......"