Convert from PDF to SWF file

Hey there,

After I convert PDF to SWF file using the pdf2swf command , most of pages look perfect, but only one PDF page lose some quality ( I attached the file as reference-convert back from swf to PDF)

On the top of the Page, there is "Welcome" Text, and it seems that it was shaped by a white box, which is not exist on the Original PDF file.

Thanks,
T