If you place high resolution images in PowerPoint 2007 presentations (say, above 220 dpi*), save the file and then reopen it, you may notice that the photos or graphics no longer appear as sharp as they should. This is because PowerPoint 2007 automatically compresses images down to 96 dpi, the resolution of projected slideshows. Animated GIFs may also lose their animation due to automatic image compression.

What to do? You can turn off automatic image compression but you must do so before saving the file for the first time. Once you’ve saved the file, it’s too late — images are compressed. Also, you’ll have to turn off image compression for each presentation you work on (exception noted below**) as the solution provided herein only apply to the current file.
Here’s how to turn off image compression for the current file in PowerPoint 2007:

• Click on the Office Button (the tiny circle graphic in the top left corner of the PowerPoint window) and select Save As.
• In the Save As window, select Tools > Compress Pictures > Options.
• In the Compression Settings window that appears, remove the checkmark next to “Automatically perform basic compression on save.”
• As an option, you can also remove the checkmark next to “Delete cropped areas of pictures.”

• Click OK twice to return to the Save As window. Here, you can choose to save the file or cancel; either way, the compression settings you just selected will take effect.

*220 dpi: We have read somewhere (unconfirmed) that apparently 220 dpi is the default PowerPoint 2007 maximum resolution. The 220 dpi figure may be related to presentation print output (as shown in the above illustration). In any case, 220 dpi is way more than needed for on-screen shows as most projectors can’t display at that high resolution.
**The permanent solution (removing automatic image compression for all presentations) requires editing the registry, not a step for the faint of heart.