>>4448735
The target audience for that is far too limited. Pirates are just going to grab whatever they get and many customers will stick to one store.
In order to get real data you'd have to purchase the same thing across a lot of different stores.
For Kobo you can generally trust the previews, those contain the same files as the full epub and they don't even have DRM so you can extract the images directly without having to go through Calibre.
It may be more practical to simply keep an archive of the best versions and possibly splice them together from different versions with various shortcomings.

Here's two versions of a page from Taechan to Jimiko 3, a censored 1,353 × 1,920 from Kobo (preview) and an less censored 1,057 × 1,500 from DMM
https://files.catbox.moe/5uqtzh.jpg
https://files.catbox.moe/xcp19c.jpg
With some imagemagick I've turned the white in the censored image transparent and laid it over an upscaled uncensored.
The result is far from perfect, the jpeg artifects around the censored parts create some problems, but this has the advantage of being automatized.
But that approach can only work if both versions are derived from a common origin. Older released can be produced from different scans and incompatible.
https://files.catbox.moe/ykkq4b.jpg
https://files.catbox.moe/uhmadf.jpg