Picture Size issue

I added a picture to my presentation, then used that picture in a PictureFrame. When I go to resize the picture frame based on the new picture size, the picture frame ends up being approximately 1/4 the size it's supposed to be. Here's some sample code:

Picture myPic = new Picture(pres, picturePath);
pres.Pictures.Add(myPic);
...
for (int j=0; j<shapes.Count; j++)
{
PictureFrame pf = shapes[j] as PictureFrame;
if(pf != null)
{
pf.PictureId = myPic.PictureId;
pf.Width = myPic.Image.Width;
pf.Height = myPic.Image.Height;
}
}

Any idea why it's doing this? Am I missing something?

Dear Jamon,

Standard resolution of slides is ~576 pixels per inch.
Your picture probably has 300 ppi resolution.