Quote Originally Posted by Sushigaijin
You know, I've thought a lot about this topic over the last few days, and I think I have identified the Line in the Sand - believability..
I am inclined to agree that "believability" is a reasonable criteria for judging a lot of postprocessing. Unnatural duotones with a pink cloudy sky in the middle of the day for no apparent photographic or compositional reason do not work, whether intentional or not.

On the other hand, there are things like Kirilian photography which is photographing the electromagnetic field around human, animal and plant life. Colourful and unique as well as proven not to be fake, since it was started well before the advent of digital. Makes it difficult to define believability.

Ronnoco