Have you tried selecting with " magic wand" and then cleaning up?
Corel Trace is a pretty good tool but it traces all defects too and so hours of clean up are required. I use both Corel and PS.. im not too strong with PS and am much more at home with Corel.
Many illustrators will use both and flip files fron one to the other as neither has all the tools required... what we need is Corel Shop

Yes i have discovered the wonders of the magic wand i havent had access to corel trace might look into it.