Allow Default artwork Generation to a specific page other than the first

[LATINO-BICEPS]

Current behaviour for thumbnails of each book is to auto generate them from each of their first page. This works great in several cases, however is not useful for cases where the first page is blank or only contains credits to translation groups for example. At the moment, I am having this issue with webtoons - see any chapters online for Solo Levelling and half the first page is consumed by credits or blank white space which makes scrolling through thumbnails to find specific scenes useless.

I see that there is an option to do this manually by either setting it per book which is extremely time consuming with 100+ chapters or renaming files for local artwork assets. I suppose I could write a script that would take extract the middle of each cbz archive and rename it accordingly but the option to do it automatically would be ideal.

edit:
For the time being this is my quick and dirty solution

#!/bin/bash
# https://komga.org/docs/guides/local-artwork-assets
# iterate and extract the 4th page from each chapter

archive_dir=$1
file_name=004.jpg

cd $archive_dir

for file in *.cbz; do
    echo "$file"
    # force extract only the specified page
    unzip -o -q "$file" "$file_name" -d "$archive_dir"
    # rename the page to the name of the archive
    cover_name=$(basename "$file" .cbz).jpg
    mv $file_name "$cover_name"
done

$ ./rename.sh my-comic-dir/

[gotson]

How would you see that configured ? This would quickly become a headache IMO.

[LATINO-BICEPS]

Ideally it would be done at the library level as it has already been done for Series Cover, but for Book Cover instead.

I am not sure how trivial it is to expand on the current implementation of only generating artwork from the first page, to being able to specify a page -> then if it doesn't exist -> default back to the first page. It does not have to be smart and detect if N% of the page contains useful information.

As a quick aside, I am aware of being able to set current page as a poster for the book. However, with 100+ chapters (100+ books) this quickly becomes unfeasible.

[gotson]

Note that you can already set the current page of any book as the poster for the book or its series: