Originally Posted by fading
I've done all those things however and the text still looks poor...
I replaced that NRhtml2mobi.exe file in the 'bin' folder of PDFRead, and my settings for conversion are as follows:
profile - prc-mobi-p
unpaper - v
dilation DPI - 900
cropping percent - 2.0
colors - 256
edge level -5
NO DILATION - TICKED
OPTIMIZE PNGs - TICKED
The file I have been left with is attached - as you can see, it doesn't look great when any level of zoom is set.
OK, you're probably not going to like the answer, but due to those crop marks, the margins cannot be removed by PDFRead by itself. It can however, when using unpaper to strip them - see this post
on how to do just that; needs experimentation, perhaps on a few pages at a time.
The idea for displaying pdf pages on small screen ebook devices is to somehow gain back those white margins (when using portrait-mode) OR use a landscape profile/mode (see attached screenshot). However, this will require two page turns for each pdf pages. (I told you wouldn't like the answer...
But there's no other way to increase the clarity/readiblity of the text unless the image can be "zoomed-in" on the ebook page via white margin removal or landscape mode.