Bug 448462 - PDF images may display repeated rectangular artefacts in the background at certain zooms
Summary: PDF images may display repeated rectangular artefacts in the background at ce...
Status: CONFIRMED
Alias: None
Product: okular
Classification: Applications
Component: printing (show other bugs)
Version: 21.12.0
Platform: Mint (Ubuntu based) Linux
: NOR normal
Target Milestone: ---
Assignee: Okular developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-01-14 14:07 UTC by rgreen
Modified: 2022-01-16 23:06 UTC (History)
1 user (show)

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


Attachments
PDF showing visual artefacts at certain zoom settings (1.28 MB, application/pdf)
2022-01-14 14:07 UTC, rgreen
Details
Screenshot of Okular PDF artefacts at 120% zoom (137.75 KB, image/png)
2022-01-16 10:47 UTC, rgreen
Details
Screenshot of part of original pdf showing artefacts at 120% zoom (572.60 KB, image/png)
2022-01-16 12:08 UTC, rgreen
Details

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Description rgreen 2022-01-14 14:07:12 UTC
Created attachment 145458 [details]
PDF showing visual artefacts at certain zoom settings

SUMMARY
***
At certain zoom levels pdf images may display repeating rectangual markings whose size is related to the zoom level.. 
***
STEPS TO REPRODUCE
1. Open the attached pdf ("artefact"). This is actually an image, although text is displayed.
2. Set zoom level to 100%, then 110%.
3. Now, set zoom to 120%, then 125%.

OBSERVED RESULT

The view is as expected up to 110%. However, at 120%, you can definately make out repeating, bluish, rectangles in the background. These become very much smaller at 125%, and gradually fade away at incrementally larger zooms up to 150% or so.

EXPECTED RESULT

Obviously, there should be no such visual artefacts at any zoom.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma:  Linux Mint
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 5.89
Qt Version: 5.15.3

ADDITIONAL INFORMATION

No artefacts were visible when viewing the same document at similar zooms in Xreader.
Comment 1 Albert Astals Cid 2022-01-15 23:44:22 UTC
Please attach a screenshot of such artifact
Comment 2 rgreen 2022-01-16 10:47:32 UTC
Created attachment 145530 [details]
Screenshot of Okular PDF artefacts at 120% zoom

See attached. If you zoom the png image you will see the artefacts change in a similar way to how they zoom in the pdf. They are somewhat faint, but if viewing on a laptop they become clearer by changing the angle of the screen.
Comment 3 Albert Astals Cid 2022-01-16 11:29:23 UTC
That image doesn't match with the PDF you attached.
Comment 4 rgreen 2022-01-16 12:08:45 UTC
Created attachment 145535 [details]
Screenshot of part of original pdf showing artefacts at 120% zoom

OK, here it is.
Comment 5 Albert Astals Cid 2022-01-16 23:06:53 UTC
I can defenitely not see that kind of artifacts but i can reproduce some different ones, at much lower zoom levels though. Needs someone with time to investigate, most probably a poppler bug.