This “how much is too much” question is an interesting one, but I think it’s a bit misleading. A better question, for me, is does an image tell me something about the world or show me something that I might not otherwise have seen? If the answer is yes, it’s a good photograph, irrespective of the amount of post-processing or the effort that went into an image’s creation. For example, Ansel Adams work relied on “his” vision – the strength of his work is directly related to his skill in converting a negative to a print that captured his vision of the world. For anyone to say, “but that’s not how it looked!” would be to miss the point of what he was trying to convey. And the same principle applies to digital editing – it’s about using the tools at your disposal to create an image that says what you want to say. Perhaps “too much” is when it’s done badly, when it’s “too” obvious, or when it’s simply done for effect.