Add Humble Bundle PDF support

[axu2]

Humble Bundle PDFs are vectors and text-based text, not images. They are also much higher quality that the epub and cbz provided.

But you can use mutool to convert the HQ pdf to HQ CBZ. I use 1920 since that's the height for kindle scribe, but you should do whatever your kindle height is.

Windows:

winget install --id=ArtifexSoftware.mutool  -e
for %%I in (*) do mutool convert -O height=1920 -o "%%~nI.cbz" "%%~nI.pdf"

macOS:

brew install mupdf-tools
for f in *.pdf; do mutool convert -O height=1920 -o ${f%%.*}.cbz $f; done

https://www.reddit.com/search/?q=kindle%20mutool

https://mupdf.readthedocs.io/en/latest/mutool-convert.html

This is probably a better idea than adding epub support in

• EPUB Input [Enhancement] #277

Example converted png from pdf: