Bug 75346 - [SLIDESHOW] Images scaled down poorly, resulting in aliasing/moire patterns
Summary: [SLIDESHOW] Images scaled down poorly, resulting in aliasing/moire patterns
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
(earliest affected) release
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Not Assigned
Depends on:
Blocks: Slide-Show Impress-Images
  Show dependency treegraph
Reported: 2014-02-22 03:40 UTC by Mike Doherty
Modified: 2019-08-19 07:07 UTC (History)
2 users (show)

See Also:
Crash report or crash signature:

Editing view - no moire pattern (614.68 KB, image/png)
2014-02-22 03:41 UTC, Mike Doherty
Presentation view - severe moire pattern (1.69 MB, image/png)
2014-02-22 03:42 UTC, Mike Doherty

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Description Mike Doherty 2014-02-22 03:40:39 UTC
I have a presentation with a very large image. In editing view, it gets scaled down nicely, and there's very little in the way of aliasing or moire pattern visible. When I run the presentation, the image is scaled poorly, and severe moire patterning is visible. The same thing happens if I remove the background and instead insert the image as a normal image object in the slide itself.

I have both hardware acceleration and antialiasing enabled in Options > View > Graphics output.

The best workaround is to:
  - scale the image to the right size and resolution yourself outside Impress, or
  - insert the image as an image object within the slide, and then right-click on it, and select "Compress graphic" to scale it down to size

Either of these will permanently change the image in your presentation, so you might end up changing the image for each different output device.

Instead, Impress should scale the image down better.

I'll attach screenshots showing the effect shortly.
Comment 1 Mike Doherty 2014-02-22 03:41:34 UTC
Created attachment 94548 [details]
Editing view - no moire pattern
Comment 2 Mike Doherty 2014-02-22 03:42:28 UTC
Created attachment 94549 [details]
Presentation view - severe moire pattern
Comment 3 Jean-Baptiste Faure 2014-04-21 20:12:14 UTC
Please could you attach a presentation document showing the problem?

Note: we do not need your photo and your cv, the part of the cloth showing the moire effect.

Best regards. JBF
Comment 4 QA Administrators 2014-11-02 16:46:31 UTC Comment hidden (obsolete)
Comment 5 Mike Doherty 2014-11-02 18:00:44 UTC
I've uploaded a presentation with just the one problematic slide to Dropbox, because it's too large to be uploaded here: https://db.tt/pOAmrtYc
Comment 6 Buovjaga 2014-11-16 17:37:20 UTC
(In reply to Mike Doherty from comment #5)
> I've uploaded a presentation with just the one problematic slide to Dropbox,
> because it's too large to be uploaded here: https://db.tt/pOAmrtYc

Moire reproduced on Ubuntu and not reproduced on Windows.

Win 7 64-bit Version:
Build ID: b021b5983c62e266b82d9f0c5c6d8d8900553827
TinderBox: Win-x86@39, Branch:master, Time: 2014-11-12_01:10:08

Ubuntu 14.10 64-bit Version:
Build ID: 3cf226622a3d8c09d655034dbcc81695f1662b87
TinderBox: Linux-rpm_deb-x86_64@46-TDF-dbg, Branch:master, Time: 2014-11-15_23:24:22
Comment 7 QA Administrators 2015-12-20 16:15:42 UTC Comment hidden (obsolete)
Comment 8 QA Administrators 2017-01-03 19:49:18 UTC Comment hidden (obsolete)
Comment 9 Buovjaga 2019-01-11 11:29:24 UTC
The Dropbox link is now 404. Our upload limit is currently 30MB. Mike: please attach the presentation. Well, re-test before uploading.
Comment 10 QA Administrators 2019-07-11 02:55:35 UTC Comment hidden (obsolete)
Comment 11 QA Administrators 2019-08-19 07:07:30 UTC
Dear Mike Doherty,

Please read this message in its entirety before proceeding.

Your bug report is being closed as INSUFFICIENTDATA due to inactivity and
a lack of information which is needed in order to accurately
reproduce and confirm the problem. We encourage you to retest
your bug against the latest release. If the issue is still
present in the latest stable release, we need the following
information (please ignore any that you've already provided):

a) Provide details of your system including your operating
   system and the latest version of LibreOffice that you have
   confirmed the bug to be present

b) Provide easy to reproduce steps – the simpler the better

c) Provide any test case(s) which will help us confirm the problem

d) Provide screenshots of the problem if you think it might help

e) Read all comments and provide any requested information

Once all of this is done, please set the bug back to UNCONFIRMED
and we will attempt to reproduce the issue. Please do not:

a) respond via email 

b) update the version field in the bug or any of the other details
   on the top section of our bug tracker

Warm Regards,
QA Team