I’m doing the formatting/pre-press for a book to be printed as a hardcover at Amazon or maybe Barnes & Noble. Using InDesign and saving as a PDF. The source document is a Word file with 59 photos, none of which seem to be 300 dpi, and the original photos aren’t available. I can place the Word file in InDesign and the embedded photos show up somewhere around Actual PPI: 72 and Effective PPI: 181, or maybe Actual PPI: 220, Effective PPI: 220. Will they print OK and will the file even be accepted by the printer? Or do I need to copy and paste all the photos into Photoshop and save at 300 dpi and then place them into the InDesign file? Thanks!
Make sure your Word file is in the .docx format and not .doc.
Make a copy of your Word file at the desktop level.
Change the .docx extension to .zip.
Expand or open the zip file.
Go into the "doc" folder.
Remove the "media" folder.
Use Adobe Bridge to identifiy and inspect the resolution of the graphics.
If they are any better than what you see in InDesign, place those instead.
You may want to use Bridge to rename the graphics.
(This whole process takes about a minute.)
To answer your question, If you can get around 200 ppi, that should suffice. If lower that that, they may ask you to sign a waiver so you can't complain about the quality. Bringing the low-res images into Photoshop and increasing the resolution will help a little, but should only be a method of last resort. You may want to run a little sharpening on the image afterwards.