[Request] Split large images over many pages

[badbob001]

I'm reading translated Japanese light novels and they often start with a few graphic-only pages that are too small to read on a reader. Propose option to split this graphics into multiple pages. I think the person that created the browser-based file-transfer epub optimizer did something similar in an earlier web-hosted optimizer app.

Workflow:

• Specify viewing direction of images (left-to-right or right-to-left).
• Specify if device is held in portrait, then specify if split images should be rotated landscape CW or landscape CCW orientation. The idea is that even if you're reading in portrait, split images will be shown in landscape.
• Specify if the cover image should be split. The split images of the cover will be added to pages after the original cover page so the full cover image is still used for book thumbnails and screensaver.

1. If there are large landscape images, split them into 2 portrait images based on viewing direction.

┌1───────┐┌────────┐           ┌1───────┐    ┌2───────┐
│                  │           │        │    │        │ 
│                  │           │        │    │        │ 
│                  │    ->     │        │    │        │ 
│                  │           │        │    │        │  
│                  │           │        │    │        │ 
└────────┘└────────┘           └────────┘    └────────┘

2. For each large portrait image (including ones created from landscape images), split from top-to-bottom into smaller images that fits the target device's landscape orientation of the screen. This type of split is often used for viewing webtoon images.

┌1───────┐          ┌1───────┐
│        │          └────────┘
│        │          ┌2───────┐
│        │    ->    └────────┘
│        │          ┌3───────┐
│        │          └────────┘
└────────┘          ┌4───────┐
                    └────────┘ 

3. If the device is specified as having portrait orientation, rotate the split images as specified. This allows the image to be viewed correctly when the device is temporarily physically rotated to landscape to view the image.

╭─┐──────────╮ 
‖ │┌1───────┐│      ┌2───────┐      ┌3───────┐      ┌4───────┐
‖ │└────────┘│      └────────┘      └────────┘      └────────┘
╰─┘──────────╯ 

Note: Don't need to make this into a full-blown manga viewing feature where we split each image into a grid of smaller images and then view them in a specific reading order. There are existing tools for image-only books. But they don't work on epub.