One of PowerPoint’s greatest qualities is that you can get all sorts of content from disparate sources and add them all within one presentation to create a unified document. Pictures are one of the most important content types you add on your slides — however, each picture you insert may have different resolutions — and thus even though you may have sized your picture to look like a small postage stamp on your slide, it may be increasing your file size by several megabytes. You can of course manually compress pictures in your presentation — additionally, you can set the document resolution for any presentation — this option will compress pictures you insert automatically to the default resolution you set.
Learn how to set document resolution in PowerPoint 2010 for Windows.

