However, I don't think a huge AviSynth script that started with the DVD as its source would either be illegal or violate any patents. So you could do all the colour correction, re-editing, etc., you liked, put it in an AviSynth script, and sell that. I'll bet you could even sell the mattes and other differences between the frame you want and the frame you've got, since you'd be creating those works yourself. I would guess that you can't copyright the differences between one copyrighted work and another, just by owning the copyrights on the two works at either end.
However, I don't think a huge AviSynth script that started with the DVD as its source would either be illegal or violate any patents. So you could do all the colour correction, re-editing, etc., you liked, put it in an AviSynth script, and sell that. I'll bet you could even sell the mattes and other differences between the frame you want and the frame you've got, since you'd be creating those works yourself. I would guess that you can't copyright the differences between one copyrighted work and another, just by owning the copyrights on the two works at either end.