Quick way to resize PDF scans en masse

Hello everyone,

I work for a media production company (i.e. DVDs, digital downloads, .epubs, etc), and one of our objectives is to be able to quickly and efficiently produce PDFs fitting the format requirements on the website Create Space, who prints physical copies of books that we give to them in PDF file format. Create Space requires extremely specific document sizes in order to print the physical copies (i.e. I have a book that is 5.5x8.5 paperback cover dimensions. Create Space accepts books that are sized at 5x8). The scanner that I have is a Brother ADS-1000W, which offers an automatic feeder and double-sided scanning options.

The issue that I am having is that the scanner offers a limited amount of page sizes that are tailored to the general office paper sizes (i.e. 5x7, 8.5x11, etc) as opposed to allowing me to customize the options to work with a specified dimension. What happens subsequently is that the books that aren’t exactly the size Create Space wants will be automatically rejected if I attempt to upload these.

Where LibreOffice comes in, is that I know that I can resize pages and objects with ease using the Draw program, however, I was wondering if there’s a way to quickly resize the objects that the scans come up with quickly and in large quantities (I know that you can crtl-a to reformat all of the page dimensions themselves, which is more or less what I’m aiming for with the objects). To better explain what I’m aiming for:

I have 100 pages for a book that I want to take from 5.5x8.5 dimensions to 5x8. I scan these using the Brother scanner, then open the first page of the book using Draw. I format the page and object to be 5x8, and then place the rest of the book pages in. Draw then prompts me with the question of wanting to scale all of the source pages down to the target page size, which it successfully does. The issue I have then is that it is only scaling the page generated by Draw itself, not the actual PDF scan (object). What I end up with is 100 pages that have the Draw generated pages correctly sized, and 99 incorrectly sized PDF objects.

If screenshots or a video screen capture would be helpful in my explanation, I am more than happy to provide these if requested.

So ultimately, my questions is: How do I create a rule in Libre Draw to cause large quantities of PDF scans to become a specified size, as opposed to a scaled size?

Many image applications can resize images in batch mode.

Scan to images, batch resize, then create the PDF from the images.

Thank you for the solution!