I have some PDF which I want to print out as hardcover. Sadly, the PDF is in a non-standard format (some weird American format, I guess), so I need to scale it to A4. The online print service I want to use tells me exactly how large the PDF shall be. So I open the PDF with Preview, open the Print dialog, select my custom paper size (A4 + some margins) and print it with PDFwriter.
Sadly, after sending the resulting PDF to the print service, the web interface says that the image resolution is too low. The source PDF has been distributed for printing purposes, so I am pretty sure that the image resolution is proper for printing it. Therefore, I guess that PDFwriter reduces the image resolution when creating the A4 PDF. I cannot find the setting for changing this.
How can I scale my PDF so that the images do not lose resolution?