Bug 416659 - Okular PDF line rendering worse than in other PDF viewers
Summary: Okular PDF line rendering worse than in other PDF viewers
Status: RESOLVED UPSTREAM
Alias: None
Product: okular
Classification: Applications
Component: PDF backend (show other bugs)
Version: 1.6.3
Platform: openSUSE Linux
: NOR normal
Target Milestone: ---
Assignee: Okular developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-01-23 18:43 UTC by Tommi Nieminen
Modified: 2020-01-23 19:03 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
Sample PDF drawing in Okular vs muPDF (22.46 KB, image/png)
2020-01-23 18:43 UTC, Tommi Nieminen
Details

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Description Tommi Nieminen 2020-01-23 18:43:34 UTC
Created attachment 125344 [details]
Sample PDF drawing in Okular vs muPDF

SUMMARY

Okular tends to have trouble rendering line drawings exactly in PDF files. This is especially noticeable in varying line widths or the spacing of dots in dotted lines (as shown in the attached sample screenshot).

STEPS TO REPRODUCE
1. Produce a PDF file with a line drawing.
2. Compare line widths in Okular and another PDF viewer such as Zathura or muPDF.

OBSERVED RESULT

In Okular, line widths vary without any apparent pattern. muPDF and Zathura produce top-quality results.

EXPECTED RESULT

Line widths should follow whatever is in the PDF file.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSUSE Leap 15.1
KDE Plasma Version: 5.12.8
KDE Frameworks Version:  5.55.0
Qt Version: 5.9.7

ADDITIONAL INFORMATION

The attached image shows how different line widths appear in Okular vs. in muPDF, which (despite the 96 dpi rendering) produces uniform line widths.
Comment 1 Yuri Chornoivan 2020-01-23 18:50:36 UTC
Does "Enhance thin lines" in PDF backend configuration help?

https://docs.kde.org/trunk5/en/kdegraphics/okular/config-pdf.html

Can this problem be observed in other poppler-based viewers (qpdfview, Evince)?

thanks in advance for your answers.
Comment 2 Tommi Nieminen 2020-01-23 19:00:30 UTC
(In reply to Yuri Chornoivan from comment #1)

> Does "Enhance thin lines" in PDF backend configuration help?

Doesn’t seem to have any effect. I tried both options, “Solid” and “Shape”. (I closed and restarted Okular while doing this but I didn’t log out and in to make sure the settings propagate.)

> Can this problem be observed in other poppler-based viewers (qpdfview,
> Evince)?

I tried qpdfview now and for sure it looks exactly like Okular, so to the problems seems to be backend-related.
Comment 3 Yuri Chornoivan 2020-01-23 19:03:51 UTC
Please report the bug against poppler.

https://gitlab.freedesktop.org/poppler/poppler/issues/new?issue

Thanks.