kymarto wrote:
Generally speaking, pictures can be optimized in terms of exposure and color, without manipulations that affect the impact of the photos. For instance, correction of lens vignetting is fine, but darkening or lightening specific areas to draw attention to a face or a certain area of the photograph, for example, is not allowed. Manipulation of pixels, such as removing, adding, altering or moving objects, is a complete no-no.
But the standards of manipulation are stricter now than in the film era. One of our greatest photojournalists, W. Eugene Smith, routinely darkened backgrounds or areas he felt weren't important to make the main subject stand out, or lightened (sometimes using bleach) areas he felt were important, and nobody seemed to object.