WPF Image Background issue

HI,

I have BitmapSource from physical image.

private void RenderImage(BitmapSource source, DrawingContext dc, Rect imageRect, bool isPrinting)
        {

I use Image object to create Image from bitmapsource:

 Image bgImage = new Image() { Source = source };

}

Is there any way I can find out that my image is transparent of it has white background. There are 1000 images in my project and I want to find out for each.

I also have to make sure that solution of this wont cause performance issue.

Thanks

Dee