I don't know a lot about the jargon of the editing pictures, but sometimes it's restorations (not too much), because I am a little a maniac concerning the quality and when I zoom on the page with my tablet, the bubbles or cases are sometimes too much pixelate.
To answer your question, for the scanners who try to do high quality, I believe that they retouches a lot the contrast, the optimized fuzziness and the mitigation of fuzziness, they play a lot on the neatness and the shine of colors(...) In brief I'm not an expert in this ^^ " but these people want to reach a level which competes with a pure digital comic book (as the Infinite comics of Marvel for example)