Bug 338138 - Preview uses low quality interpolation
Summary: Preview uses low quality interpolation
Status: RESOLVED FIXED
Alias: None
Product: digikam
Classification: Applications
Component: Preview-Image (show other bugs)
Version: 4.2.0
Platform: Gentoo Packages Linux
: NOR normal
Target Milestone: ---
Assignee: Digikam Developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-08-08 22:09 UTC by DrSlony
Modified: 2014-08-23 11:05 UTC (History)
7 users (show)

See Also:
Latest Commit:
Version Fixed In: 4.3.0
Sentry Crash Report:


Attachments
Screenshot showing image preview (957.03 KB, image/png)
2014-08-08 22:09 UTC, DrSlony
Details
It should look like this (199.15 KB, image/jpeg)
2014-08-08 22:10 UTC, DrSlony
Details
bad quality preview (127.99 KB, image/png)
2014-08-09 20:09 UTC, Vincent Barberet
Details

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Description DrSlony 2014-08-08 22:09:15 UTC
Created attachment 88170 [details]
Screenshot showing image preview

I haven't noticed this before so it's possibly a new bug. digiKam 4.2.0 uses a low quality interpolation algorithm resulting in horrible previews.
Comment 1 DrSlony 2014-08-08 22:10:39 UTC
Created attachment 88171 [details]
It should look like this
Comment 2 Veaceslav Munteanu 2014-08-09 06:52:08 UTC
I think the problem is relevant to #337231

*** This bug has been marked as a duplicate of bug 337231 ***
Comment 3 DrSlony 2014-08-09 08:44:55 UTC
Are you sure?

I skimmed through that bug report. Seems to me if these bugs are related then I would see a jagged preview even when no scaling is performed, i.e. when the image fits inside the digiKam preview space, yet that's not the case - when no scaling is performed the preview looks good.
Comment 4 Robert Zeller 2014-08-09 10:07:43 UTC
Yes, I think both phenomena (grainy preview & artificial patterns on image parts with regular repeating structures like e.g. brick walls) are related. I am encountering both on DK 4.2., when preview-full-size-of-image is set to true. This was not the case in DK 4.1
Comment 5 Veaceslav Munteanu 2014-08-09 11:41:32 UTC
The only modification that could affect preview is support for Macbook's retina displays. Developer who proposed patch will wrap code for Mac OS, just wait.
Comment 6 Vincent Barberet 2014-08-09 20:09:38 UTC
Created attachment 88191 [details]
bad quality preview
Comment 7 Vincent Barberet 2014-08-09 20:11:54 UTC
Comment on attachment 88191 [details]
bad quality preview

Here is a zoom on the issue I'm facing. It seems similar to other attachments. Please tell me which info is needed to troubleshoot this issue.
Comment 8 caulier.gilles 2014-08-15 10:57:29 UTC
See comment 21 from bug 337231 for the future solution :

https://bugs.kde.org/show_bug.cgi?id=337231#c21

Gilles Caulier
Comment 9 caulier.gilles 2014-08-17 10:26:58 UTC
Git commit 2e03ccdb9319e40b8e40cabea569c8656053171f by Gilles Caulier.
Committed on 17/08/2014 at 10:24.
Pushed by cgilles into branch 'master'.

apply new patch #88275 from Axel Arnold about Retina display support will be only managed under OSX, not Linux or Windows.
Related: bug 337231

M  +7    -0    CMakeLists.txt
M  +3    -0    digikam/utils/config-digikam.h.cmake.in
M  +5    -0    libs/widgets/graphicsview/graphicsdimgitem.cpp
M  +5    -0    utilities/imageeditor/widgets/imagepreviewitem.cpp
M  +5    -1    utilities/slideshow/slideshow.cpp

http://commits.kde.org/digikam/2e03ccdb9319e40b8e40cabea569c8656053171f
Comment 10 DrSlony 2014-08-17 14:35:45 UTC
Great! Now when is 4.2.1 out? :)
Comment 11 caulier.gilles 2014-08-17 17:49:53 UTC
Not 4.2.1, but 4.3.0.

Look release plan :

https://www.digikam.org/about/releaseplan

Gilles Caulier
Comment 12 DrSlony 2014-08-17 19:17:07 UTC
Thank you.
Comment 13 DrSlony 2014-08-23 11:05:05 UTC
Thank you!