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Hi. I rescanned the illustration and get it processed by waifu2x to make lines clear, also I put a piece of white paper below when scanning so that colors of the page behind can't show through the paper. Which post do you think is better? I'm a freshman of scanning, using EPSON V19. How does you guys scan so well? Please teach me. Much appreciated.
Doesn't look too bad to be honest.

If anything, I think the filter now is a little bit too strong as the lines became overshapen. And some low frequency noises are still there.

I recommend to process it with typical filters like greyc/noiseware/whatever you like first to deal with low freq noises and break screening pattern, and then finish it with waifu2x with lighter strength.