[iText-questions] PdfPTable with transparent background color ?

[[EMAIL PROTECTED]]

Sorry for my previous e-mail
my English is a disaster

Now I retry to explain my problem :

I create a pdf document using a PdfPTable class to create a table (see the attachment)
I also add a watermark on the document.

For more readeable table, I set an alternate gray background using the below code

                    if (row % 2 == 1) {
                        cell.setGrayFill(0.9f);
                    } else {
                        cell.setGrayFill(0.0f);
                    }

but In this manner the setGrayFill method cover the watermark image.

How I can set a background color (transparent) without cover the watermark image ?

Thanks in advance.

<<attachment: Table.jpg>>