Depends on the purpose of the algorithm. If the purpose of the algorithm is, for instance, to simulate as accurately as possible the curvature of earth, then while the algorithm itself might be creative, and worthy of copyright, the resulting output wouldn't be. (If the purpose of the algorithm is to make a pretty picture, then it probably would be.)
It sounds like you're saying copyright depends on the intention of the creator - I'm not sure that's true. If the output is the same, it shouldn't matter if it was intended to be an accurate representation or intended to look pretty. It's the same piece of work, created the same way, so it has the same copyright.
Would you say a painting made using a rubber stamp wasn't creative because anyone can cover stamps in paint and put them on a piece of paper? The creativity comes in making the stamp, and so, what you make with that stamp is copyrightable.
A painting made using a rubber stamp is a copy of the stamp. Not all output from computer algorithms are copies of that algorithm.
Would you say a photograph made using a camera was copyrighted by the person who wrote the firmware on the camera (the image stabilization algorithm, the sharpening algorithm, etc.)? Of course not. The algorithm is likely copyrighted by the programmer (the standard for creativity in computer software is unfortunately very low), but that doesn't mean the output of the software is copyrighted by the programmer.
Yeah, it's a bad analogy. Sorry.