You can reduce the file size of a presentation and save disk space by compressing pictures in your document. The compression options reduce both the file size and picture dimensions based on how you intend to use the picture, such as viewing on screen or in an email message. You can compress all pictures in the file or just the ones that you select. 

Note: Compressing a picture to reduce the file size changes the amount of detail retained in the source picture. This means that after compression, the picture can look different than before it was compressed.

Compress pictures

1. To compress all pictures in your presentation, click File > Compress Pictures.

   To compress only selected pictures, hold down SHIFT, click the pictures you want to compress, and then click Compress Pictures  on the Picture Format tab.

2. Select one of the following in the Picture Quality box:

   To compress pictures for	Do this
   Printing	Click Print (220 ppi).
   Viewing on screen	Click On-screen (150 ppi).
   Sending in an email message	Click Email (96 ppi).
   Keeping the current resolution and minimizing changes to the picture	Click Use original quality.

   Tip: If you have cropped any pictures, you can reduce the file size even more by selecting the Delete cropped areas of pictures check box.

3. Click Selected pictures only or All pictures in this file.

   Note: If you used the File menu to choose all pictures in step 1, these options will be unavailable. Compression will be applied to all pictures in your presentation.