If you want to extract the full resolutions of the images from a powerpoint (PPT) presentation, then follow this easy steps:
1. In PowerPoint 2007/2010 (maybe 2008/2011?) the .pptx file is actually a compressed folder.
2. Copy the file, change its file extension to .zip, and you can extract its contents.
3. In the extracted folders \ppt\media you’ll find jpegs for all the images at the highest resolution they have been saved.
For 2003 ppt format, follow these steps:
1. Make the slide as big as possible and drag the corner of the graphic you wish to print to make it as large as possible within the slide.
2. Go to file options and choose “Save as Web Page…” via the File Menu.
3. Below the explorer window in that dialog is a button labeled “Publish”, click this and you are presented with yet more options and another button “Web Options”.
4. Click this and again go to "more options", and select the "Pictures tab" on that dialog box
5. Change the “screen size” to the highest value (1920×1200).
6. Click OK in that dialog and Publish in the next.
The result will be a clutch of new files in your folder, a static website based on the original Powerpoint slideshow. Go to the web page files folder and open it. In this folder you will find a large-ish png file, which will hopefully have pixel dimensions of 1920×1200, which is perfectly adequate for printing at about six inches width screening at 300 dots-per-inch (not to be confused with desktop printer resolution, by the way), this is print for screened publications such as newspapers and magazines.
Source: http://www.sciencetext.com/extracting-images-from-powerpoint-files.html,
You can also refer to http://support.microsoft.com/kb/827745.
