I've got a similar issue - a bunch of contours I've made into a surface, and from there an image which I'll use later. Lots of holes due to how fine the contours are and how low I'm having to set the resolution.
Working in Manifold 8, but never done anything with images before. Any idea where I'd find the interpolation option you used (even if it means having to transform the image again)?
EDIT - never mind, found it!