Scan Tailor will output 600 dpi black and white images (around 3000x5000, depending on the book) which compresses great. But don't resize them, tho. Antialiasing adds unnecessary information and they won't be 1 bit images anymore. I don't like repeating myself very often so just read: https://www.mobileread.com/forums/sho...d.php?t=173214
Anyway, you shouldn't have scanned straight to PDF. Now you'll probably have to extract the images from the PDF because you can't just feed Scan Tailor anything. How would you do that? I don't know. Maybe print to a virtual printer that outputs PNG or TIFF images. You'll have to do some googling.