No easy ones I know of. Have done it but it was a pain.
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Crop the pages so that headers, footnotes and page numbers arent part of the book anymore. Use Briss for that.
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Convert to html, not sure which is the best software though
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Clean up manually. That is the most work, mostly newlines and stuff. Dont even try without Regex.
I dont bother anymore, for smaller pages I do the cropping and read on kindle. Larger on tablet.
Have a look at this forum for more in depth knowledge: https://www.mobileread.com/forums/forumdisplay.php?f=184