ImageMagik can convert ENTIRE book. But security prevent it (normally) using a PDF as source. So step one is open the PDF in The Gimp (or possiblly photoshop). Each page is a layer. Export in reverse order as a motion png, that's a PNG with a frame for each page, an mpng or mng.
ImageMagik will convert that to PDF.
or use
https://www.mobileread.com/forums/sh...d.php?t=144711