To convert a pdf into navigable html (with images intact), you can use pdftohtml:

E.g.,

 pdftohtml -c originalfile.pdf  newname_template.html

Converting a book-length pdf using this method gave me a directory full of files, with consecutively numbered html files representing the pages.   Names were based on the ‘newname_template’ supplied, as were the png image files.  Not the prettiest, but functional, and viewable on devices lacking native pdf-rendering capabilities.