How to get picture in PowerPoint2007?

[How to get picture in PowerPoint2007?]

Hello ,Everyone
In PowerPoint 2007,use vsto
How to get Slide background picutre?
And,if the Slide use Layout or Master how to get background picutre?
if a shape is fill with picutre,How to get the picture?

I try to use Export method,but is not apply to rotated PictureShape and the
shape filled with picture, the picture file quality is poor.

Another,How to get gradiant color from background,I always get same color
from GradiantStops property.



Thank you.