Given a published paper, as a Computer Scientist, I see an opportunity to extend the work and methodology of previous authors.
By modifying the presented work, introducing some concepts and a different approach for input parameters (for example) my "new" work can achieve better results than the results presented by the original authors.
In some cases, the modifications I suggest are not extensive or radically divergent, but even this way the results are better than the current state of the art.
Is there considered to be a minimum change from the methodology in the original paper, to publish an extension of that earlier paper from other authors?
EDIT: By extending I mean: writing a paper emphasizing the modifications that produce improved/better results, instead of copying significant passages from the original work results.