poor font rendering on encrypted PDF files

[Greg Marks]

After running either the command "pdftk in.pdf output out.pdf user_pw password" or the command "qpdf --encrypt password password 128 -- in.pdf out.pdf" to create an encrypted file "out.pdf" from an unencrypted file "in.pdf," when viewed with qpdfview, the encrypted file (after being opened with the password) displays much less crisply than the original, unencrypted file. I suspect this is an issue with the Poppler library. This bug occurs with qpdfview 0.4.13.99, using Poppler 0.18.4 for PDFs. (By comparison, "in.pdf" and "out.pdf" seem to display identically using apvlv, epdfview, evince, gv, mupdf, okular, or zathura.)

[Adam Reichold (adamreichold)]

Hello Greg,

thanks for taking the time to report this! Is it possible to attach both files (or some samples prepared in the same way) to this bug report so that I can easily reproduce this? Also, if Okular renders it properly, a bug in Poppler is unlikely as Okular exercises the same rendering pipeline within Poppler as qpdfview does.

Best regards, Adam.

P.S.: Screenshots along with the sample files would be even more helpful.

[Adam Reichold (adamreichold)]

Hello again,

it seems like I found the cause of this: Poppler drops all render hints like antialiasing and so on after unlocking the document. So I committed a change in trunk to explicitly restore them. Would be nice if you could test a trunk build of at least revision 1838. Thanks!

Best regards, Adam.

P.S.: Not sure if I'd call it a Poppler bug, but at least it seems to be an undocumented quirk. It also still present in the current release 0.30 of Poppler...