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Old 04-18-2026, 10:28 AM   #3
FelixKrull
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Yes, it does seem to be the images, but I’m still trying to understand how this is even possible.

In the EPUB, I see a lot of PNG files (in the built-in editor it says “1592@1.4 GB” under 'pictures'), but after conversion they appear to be massively inflated in size.

Why would PNG images grow that much during conversion? I would have expected them to stay roughly the same, or at least not increase by such a large factor. PNG is lossless.

Is Calibre reprocessing PNGs in a way that removes compression efficiency, or is this related to how AZW3/KF8 stores images internally?

Trying to understand the mechanism behind this.
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