PDM said:
is it possible to select only a part of the picture(without the background
which is always a square), so that it can be exported to power point
without
having a white background.
As Mary mentioned, PNG and GIF will support transparency. So will TIF. So
you can make that area transparent in a photo editor and then save as one of
those three file types, and PPT should recognize that transparency.
In addition, you can insert a picture inside an autoshape, which might work
for your needs. Draw an oval (or whatever) on your PPT slide, then select
it, right-click, and choose Format Autoshape. On the colors and lines tab,
click the Fill box, choose Fill Effects, then Picture tab. Choose your
picture. You can also get to this from the Fill bucket icon on the Drawing
toolbar.
PPT has a transparency wand on the Picture toolbar, but it makes only one
color in your picture transparent. So it probably won't help for what you
want, but it's definitely useful to be aware of.