After saving the image in photoshop,
Open up PowerPoint, then select View > Master > Slide Master.
In the slide master, click Format > Background.
Click on the dropdown and select Fill Effects.
Click on the Picture tab, then insert the picture from there.
Once you are done with it, close Master View.
Click File > Save As.
Click on the Save as type dropdown field, and select Design Template (.pot).
There is also an article here which you can check it out:
"Creating or Customize Templates"
http://www.rdpslides.com/pptfaq/FAQ00313.htm
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Shawn Toh (tohlz)
Microsoft Most Valuable Professional (MVP PowerPoint)
Site Updated: June 09, 2006
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