1. JPG for photos
PDF to JPG gives smaller files and suits pages that are mostly pictures. Every page becomes its own image.
2. PNG for text and diagrams
PDF to PNG is lossless, so text and lines stay crisp.
3. Only want the photos inside?
Extract images saves the pictures embedded in the PDF at their own size, rather than whole pages.
Questions
Do I get one image per page?
Yes. Each page becomes a separate image.