Leptonica appears to use Sauvola binarization instead of the improved Wolf version.

Image processing strongly depends on what image you wanna use. To find an "auto" approach, that works for every image is nearly impossible...

I once wrote a bookscanner app in Java (https://boofcv.org), where everything was done automatically (preprocessing, object detection / book extraction, skin detection / finger removal, deskewing, line-slope-correction and so on). It was very difficult to adjust the parameters, that at least most of the books looked good.