(07-03-2021, 07:45 PM)rich2005 Wrote: Well, if you scanned at 1200 ppi and the scanner outputs to a PDF then you can open the PDF at 1200 ppi and the print size should still be correct (page size taken from the PDF)

That will be a large file size. Usually 300 ppi is sufficient. Use that if it looks ok. If not bump up the ppi until you are happy with the result. Higher the ppi the larger the image is in pixels, the larger the file size when exported.

Quote:The file size is not an issue. Is the setting for ppi the same as the resolution box?

(07-04-2021, 07:55 AM)rich2005 Wrote:

Quote:The file size is not an issue. Is the setting for ppi the same as the resolution box?

Yes, where it has 100 ppi enter 1200 ppi. This is only true for your scanned pdf images. It would be easier if you scanned directly to a raster (bitmap) image, for example my scanner scans to .tif at a xxx.ppi setting.  Import that into Gimp and it is the actual size in pixels.
Your scanned pdf is just a 1200 ppi raster image embedded in a pdf wrapper. When you come to re-export as a Gimp pdf then that too is a raster image embedded in a pdf wrapper.

Gimp (and other programs) uses 100 ppi as a base resolution, because it is a Portable Document Format meant for viewing in a variety of devices as well as sometimes printing. PDF originally meant for text and vector graphics, logos etc, (both scale-able without loss ) and occasionally an embedded raster image.  Not really meant for editing.