I think I did answer you @ Kodi forum, if you're @PINA there. Anyway, just re-posting here in case, and echoing some of what @Futeko just said...
You can disable Imprex 2.0 processing engine completely. But, I'd give it a try as Impex works in similar manner to the highly regarded Darbee Darblet. It's about the levels to which you apply options w/Imprex, as over-applying it will indeed result in nasty edge enhancement, unnatural contrast, etc. I usually pick 'optimal' and have most options at 'low'. You can also, like w/Darbee, do a split screen with and w/o the PQ processing to help you decide.