For more technical details about image sizes, see Whats all this about DPI and INCHES and RESOLUTION?
Stuff on masters, etc. When you check your presentation for overside images and embedded OLE objects as explained above, check the Slide and Title Master(s) and Notes and Handouts Masters as well as the individual slides. Also check each Notes page in Notes view (graphics on the Notes pages don’t appear in the Notes pane in Tri-Pane view in PowerPoint 2000 and later). Saving as earlier-version PowerPoint files PowerPoint 97 (PC) and PowerPoint 98 (Mac) and all later PowerPoint versions compress images. Earlier versions of PowerPoint don’t. If you Save As to any format that includes PowerPoint 95 or 4 in the name, your PPT file sizes will get very large if they include images. The PowerPoint Viewer that originally shipped with PowerPoint 97 was really a PPT 95 Viewer in disguise. Guess what: To make your PPT97 file compatible with this PPT95 Viewer, the file has to be saved in PPT95 format, so the images get uncompressed along the way. If you use PPT97 and Pack and Go, you need to updat
