Image processing & editing: what is an "unmanipulated" image?

What is considered an "unmanipulated" image? As defined by photo.net:

Unmanipulated

• a single uninterrupted exposure


• cropping to taste


• common adjustments to the entire image, e.g., color temperature,
  
  curves, sharpening,


• desaturation to black and white


• dust spots on sensor cloned out

http://photo.net/photodb/manipulation

What else are you allowed to do to an image that falls under unmanipulated?

Would selective sharpening using a mask be considered unacceptable?

Answer

Considered by whom? This is both an issue that has intrigued and bothered people since the dawn of photography and a still-emerging topic that is far from settled. So, in a larger sense, there's really no meaningful answer, just a series of opinions.

But, in a specific sense, there certainly can be an answer. The definition you've taken above has a very specific use — it's the definition to use for photos in the photo.net image database. It's a pretty good, well-thought through definition and could be used elsewhere, but questions over details (like the mask-based sharpening you mention) can only be done in a specific context.

The US-based National Press Photographer's Association has this in their code of ethics:

Editing should maintain the integrity of the photographic images' content and context. Do not manipulate images or add or alter sound in any way that can mislead viewers or misrepresent subjects.

and a more-specific "Statement of Principle" on Digital Manipulation, which says in part:

Accurate representation is the benchmark of our profession. We believe photojournalistic guidelines for fair and accurate reporting should be the criteria for judging what may be done electronically to a photograph.

Similarly, the Canadian Association of Journalists, in their statement of principles and ethical guidelines, says:

Photojournalists are responsible for the integrity of their images. We will not alter images so that they mislead the public. We will explain in the photo caption if a photograph has been staged. We will label altered images as photo illustrations.

Fpr both journalistic associations, the focus is on intent, and technical details aren't mentioned at all. It's probably fair to say that this is a far less strict standard than photo.net has, and, subjectively, that seems reasonable given the context. Note photo.net's reasons for their standards: photos in that database are intended to help others learn, and it is helpful to know whether or not a high degree of post-processing was required.

If you're entering a contest, that contest should explain their rules clearly. For example, the 2010 National Geographic Photography Contest has a statement including a list of okay and not-okay. This is summed-up as:

Please do not digitally enhance or alter your photographs (beyond the basics needed to achieve realistic color balance and sharpness). If you have digitally added or removed anything, please don't submit the shot. We look at every photo to see if it's authentic, and if we find that yours is in any way deceptive, we'll disqualify it.

For artistic and personal work, there's unlikely to be any expectation that your image not be manipulated, unless you create one — in which case, you have the opportunity to be as clear as you like about your process, and your views on photographic integrity.