You can customize exporting EPUB file's cover image with Yet Comic Reader.
When you export a comic file with Yet Comic Reader, it will show you an option panel like below screenshot.
The default cover image option is using first page of comics. Normally it would be fine to use it as cover image.
But there are some cases, for example, scanned comic book that has been scanned its cover in spread which is scanned front-end and back-end covers together.
The problem is there are no way to find out which part of this image is front and the other.
Left-to-Right reading book's cover has its front cover in right side and backend cover is in left side, but Right-to-Left reading book has opposite way.
Anyway this is developer's problem, not yours.
There are options so that you can just split it and decide which part you want to make a cover.
If the first page is landscape scale, There are two more "Cover" options are activated, "Left half of first page" and "Right half of first page".
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| Left half of first page option |
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| Right half of first page option |
The last option is for applying any image file that you like, just drag and drop any image file into the cover page preview box.
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| Drag & drop cover image |