Quote:
Originally Posted by Gormagon
Someone has to unzip the epub file, either you yourself or some program/script.
If you extract them yourself, you could delete the enlarged pictures in the azw3 file with calibre after opening the azw3 file with "edit book", then add the original pictures of the unzipped epub file....
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Maybe I didn’t explain that clearly:
I already unzipped the EPUB and looked at the images. The issue is that the images themselves are already large at that stage. So even before any AZW3 conversion, the extracted PNG files are much bigger than what the 14 MB EPUB size would suggest.
That’s why simply replacing images in the AZW3 with those from the EPUB doesn’t really help in my case, they’re effectively the same (already “inflated”) files once extracted.
So the core of my confusion is this:
How can the EPUB be only arond 14 MB, while the extracted image assets (PNG) already add up to a much larger size? Is this purely due to zip compression efficiency on PNG files, or is there something else going on (e.g. optimization tricks inside the EPUB container)?
In other words, the size jump seems to happen between:
EPUB (compressed container) > extracted contents
not just during:
EPUB to AZW3 conversion