EPUB -> Mobi = 4x larger file size. (4mb -> 16mb)
Working on a book that has 130 B/W gif images.
My first attempt was with larger image file sizes--roughly an 8mb EPUB. That wound up becoming a 16mb MOBI.
I went back and knocked down the gifs to 3-color. This decreased my EPUB to 4mb. Calibre conversion, however, resulted in a similar 15mb MOBI size.
I unpacked the MOBI and determined that Calibre is converting my 3-color 10k gifs to 50k jpegs.
Is there anything I can do to prevent this? I'm annoyed at having to do all this tweaking to decrease Amazon's stupid "delivery fee." Then I see my file sizes increasing 2x to 4x just on conversion.
I've also tried Kindlegen and that "only" results in a 2x file size (4mb to 8mb) but I don't like how Kindlegen handles formatting and ToC.
I've accepted the fact that MOBI files are typically 2x as big as EPUBs but I'm confused about why Calibre is kicking it up 4x. Does anyone have any advice on this? At this point I would be happy with a 2x file size from Calibre.