The GetPagePart method gets the images, thumbnails, fonts, and so on in a page by using the URI.
HRESULT GetPagePart( const wchar_t *uri, IUnknown **ppUnk );
The URI for a part. For example, the filter might parse the page markup and find a referenced font. The filter can use the font URI in a call to GetPagePart. The filter could then retrieve the font object that is associated with the page.
The object that is to be queried.
GetPagePart returns an HRESULT.
A filter must use QueryInterface on the return value to see what part types reside in the page.