I changed the default colour of the paper in Okular, but with a specific PDF file I obtain a weird behaviour: Okular shows the colour only for a few tenths of a second, then the paper turns white like the default settings. If you need the file please send me an email because I cannot put it here okular-19.08.3-1.fc31.x86_64
Please attach such a file
(In reply to Albert Astals Cid from comment #1) > Please attach such a file I just said I cannot put it here. I will send it to you by e-mail
There's no "paper" in that file, just a huge image that has a white background
(In reply to Albert Astals Cid from comment #3) > There's no "paper" in that file, just a huge image that has a white > background How can a 717 pages document just contain "a huge image that has a white background? I reopen the bugreport
It's amazing how you think you know more than me about this. It's very simple, your PDF is just one image per page, probably because it's a scan or a reprint of the original one. I'm going to leave this open if it makes you happy. I will also ignore your bug reports from here to eternity, you don't deserve me wasting my time on your entitled behavior
(In reply to Albert Astals Cid from comment #5) > It's very simple, your PDF is just one image per page, probably because it's > a scan or a reprint of the original one. Only page one and two are scanned images. From page 3, the document is a regular text so Okular should show the "paper" colour I specified in Okular settings, instead of a white background
Please check whether these pages contain a large white rectangle in the background -- some pdf files have that. You can check, e.g., by loading one page into inkscape. Strangely, pdf does not have the concept of 'paper color', so in particular any pdf files with non-white background have these rectangles.
Oliver Sander is right, the PDF pages contain hardcoded page-covering white rectangles that cover whatever background Okular tries to render. (I opened page 3 in Inkscape and I got that rectangle.)
*** This bug has been marked as a duplicate of bug 406646 ***