Remove Camera Backgrounds in a Book

Please note that Acrobat cannot scan. What it does is to use some software called Twain that lets it link to your scanner's software. I wrote the following a number of years ago that directly focuses on the issue you're concerned with. I hope it helps you.

https://community.adobe.com/t5/acrobat-discussions/scanning-clean-searchable-pdfs/td-p/4785435 

Hi @David Sirius ,

Adobe Acrobat is a PDF editing software not an image manipulation program. Your goal may be simple, but when it comes to all the PDF elements that takes place in a PDF document, you'll soon learn that understanding what a scan image is is not that simple at all.

For starters, a scanned image may appear to be readable to the human eye, but to the programs that are handling this particular aspect in a PDF document involves numerous layers of embedded content.

That said, you may be able to partially do some professional quality editing using other tools, like the Print Production tool => "Preflight,but it is quite advanced and cumbersome to master if you're new to PDF content creation and print production.

Scan & OCR, on the other hand, will attempt to recognize text and make text and images searcheable only, and in the process of working around scanned images it may (and will) break the static content that is produced as you continue to perform further editings in that document.

for instance, to handle the aspects of background removal, I would recommend to employ Adobe Express mobile app or the online service to remove the undesired background from all of the desired images in bulk before you import them to your final PDF document.

See here: https://www.adobe.com/express/

The free version allows you perform numerous image editing and enhancements, such as cropping and transparent background. It is extremely easy to remove backgrounds from an image file. I prefer the mobile app since it is a lot quicker and your content is easily accessible accross Creative Cloud programs with the Adobe Creative Cloud.

See all available features (free!):

Overall, yes the goal is simple since this type of work can be achieved just using the Edit Text or Edit PDF tools.

However, to work around how to fit that scanned content into a desired height and width page dimesnions, you may need to combine in your workflow additional steps with "Print to PDF". This particular step will allow you to print the edited content to a specific page format.

Nevertheless, these are not trivial tasks, specially if you are trying to edit an entire book with your current method.