Merge PDFs with background images

Hi,

done a job with merging many PDF docs together to a single new PDF. All works fine.
The PDFs are containing formatted text and a few vector objects like rectangles or cyrcles.

Now I have to insert background images in the new main document, each merged PDF with an own jpg image as background.
The text and vectors of the different merged files should naturally be in front of the background images within the new main document.

After drawing the image in the new document and then merging, the white background of the merged PDF overlapped the image, so there is a white rectangle (media box) over the image.

Is there a way to remove the white background of the PDFs before merging, so that only the text and vector objects are moved to the new document ?
Other recommendations ?

Thanks for any advice.

Frank

Doesn't work, there are still white rectangles of the merged pdf over the background images.

Using Quick library11.15 with Clarion.
Here the Code:

QPL.ClearFileList('List1')
Loop Zae = 1 to ...
     ....
    QPL.AddToFileList('List1', pathname-array)
End

DateiSumme = QPL.MergeFileList('List1', PDFDateinameNeu)
...
 If Not QPL.LoadFromFile(PDFDateinameNeu,'')
    Exit
End

!New page in new main document
Akt_Seite += 1
QPL.InsertPages(Akt_Seite, 1)
QPL.SelectPage(Akt_Seite)
QPL.SetMeasurementUnits(1)
QPL.SetOrigin(1)
QPL.SetPageDimensions(BOG:Bogengroesse_X, BOG:Bogengoesse_Y)

!capture single pdf for merging
PDF_Seite += 1
QPL.SelectPage(PDF_Seite)
QPL.SetMeasurementUnits(1)
PDF_Hoehe = QPL.GetPageBox(1,3)
PDF_Breite = QPL.GetPageBox(1,2)
PDF_ID = QPL.CapturePage(PDF_Seite)
....

!merging file x-times on one page of the new doc.
QPL.SelectPage(Akt_Seite)
QPL.DrawCapturedPage(PDF_ID, BOG:StartPosX, BOG:StartPosY, PDF_Breite, PDF_Hoehe)
....

!draw background images
HintergrundStream = QPL.NewContentStream()
QPL.SelectContentStream(HintergrundStream)
QPL.DrawImage(BauPosX, BauPosY, BAU:Bild_Breite, BAU:Bild_Hoehe)

...
!Move Image Stream  to 1
If HintergrundStream > 0
    QPL.MoveContentStream(HintergrundStream, 1)
     HintergrundStream = 0
     QPL.CombineContentStreams()
End

!PDF-Information
QPL.SetInformation(0, '1.4')
QPL.SetInformation(5, 'Demo Tools Franco')
QPL.SetInformation(6, 'Demo-Manager xyz')

!Save PDF
QPL.SaveToFile(Clip(PDFDateinameNeu))