If you put in the folder an image file, it is treated as a book that folder.
Treat as a book even if you leave harden in ZIP format image files.
Because it does not correspond to the PDF format, you need to use additional software, and re-save as an image file on its own.
I can smooth page turning by the look-ahead.
And then to automatically store page on the way to read. Without special operations, I can start reading from the middle.
I can set the number of pages / sheet, display direction, method of page turning, and animation when turning page for each item.