If I am understanding correctly what you are trying to do, then I think you want to use the camera icon on the e-ink screen. It will copy part (or all of) the page displayed on the e-ink side into an application on the LCD side. You can save the resulting image to the library using the + button. It will save as a BMP image file, which you can then export from the library, attach it to other documents, etc.

Looks like the image viewer on the LCD side with which the e-ink camera button interacts is pretty rudimentary, unfortunately. Would be nice to be able to manipulate the image or save it into various formats directly from that, rather than having to go through the library.