Originally Posted by kevin.pugh
hi folks, I stand corrected ... this is one more thing I have learned today. Thanks for the information.
I can teach you another thing.
The current version of Calibre has font subsetting. Subsetting is where when Calibre converts to ePub (maybe AZW3 as well) it checks which embedded fonts are used and also which characters from which fonts.
So if you embed a 4 family font in your ePub and the bold italic version is not used, Calibre would delete it.
Subsetting also will remove characters from the font(s) that are not used in that specific ePub. So it makes the font files smaller for the used fonts and between cutting out unused fonts/characters, this can make the ePub significantly smaller.
What I do once the ePub is done other then subsetting, I load that into Calibre, convert the ePub > ePub (turning on font subsetting in Look & Feel) and in the converted ePub, extract the font directory to replace the font directory in the finished ePub. Then I edit the CSS & OPF as needed for any fonts that were deleted.
Once that's done and the ePub validates, I delete the two ePub in Calibre and put in the finished ePub to eventually go on my Reader.