Hello all. I did a quick serach and I found nothing about his subject.
Let's say I want a nice plaster (like Plaster FX filter) with bricks. I would edit the Plaster FX filter, add a nice existing brick filter and done.
Then lets say my tweaks are worth sharing because it looks great. Is it legit to upload to the library?
If so, how should I credit the original filter makers?
I did read this "No clones or near-clones; new filters must be sufficiently different from other filters in the library." from the guidelines, but sounds unfear to me that I make a paster - brick mixer, which can be awesome, but based 80% on others job.
My view is that so long as the results are sufficiently different/non-trivial there's nothing wrong with re-using the internals of another filter. Just make sure to credit the original authors.
When in doubt you can always contact the author directly and ask for their blessing.
I see many re-mixes of my filters and I take it as a compliment.