the first photo is of a natural element, hence that its nit man-made. the shape of the first photo is more geographic then the second photo.
the second photo is of a side walk, a man-made object. the shape of the second photo is of a square, a square that was man-made, had to be put in place.
I think it would look good with a light blue or royal blue.
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.
The answer to your question is a.