Answer:
a City skyline would be pretty easy.
Explanation:
First off, this isn't really a yes or no question, this is an opinion.
My opinion is that photos that have been altered in any way should be marked. These days you never know what a person will do to say, get a job, advance a political agenda, or ruin the reputation of another person. The public has the right to the truth. Therefore, altered pictures should be marked or labeled in a way that differentiates them from others.
Is this a genuine question or a curious question?