Sounds to me like the pix were created in Photoshop (or another editor)
using color profiles. This is pretty common behavior for PPT once color
profiles get into the mix.
This is a pretty old FAQ, and the description is a bit off for your current
problem, but I believe it's the same issue. I don't know of a way to fix the
problem other than discarding color mgmt for the pictures...
Transparent areas of graphics turn black
http://www.pptfaq.com/FAQ00627.htm
--
Echo [MS PPT MVP]
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"Shannara5" <Shannara5@discussions.microsoft.com> wrote in message
news:4BA29ABC-AF8C-43C9-BAD7-A82678A7096A@microsoft.com...
> When I insert a picture (TIFF) into a slide in PPT and then save the PPT;
> when I reopen the PPT the picture is so dark it is almost black. However,
> when I convert the pictures to jpg I do not have a problem. This PPT was
> created with almost 90 pictures (TIFF). What happened and is there any
> easier
> way to fix it?