Bug 274394 - Dolphin, Dolphin kpart, and the file dialog render previews for some transparent png images on black background.
Summary: Dolphin, Dolphin kpart, and the file dialog render previews for some transpar...
Alias: None
Product: kio
Classification: Frameworks and Libraries
Component: thumbnail (show other bugs)
Version: unspecified
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: Unassigned bugs mailing-list
Depends on:
Reported: 2011-05-29 01:50 UTC by Nikita Skovoroda
Modified: 2011-06-14 23:59 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In: 4.7.0

Screenshot of the bug. (7.33 KB, image/png)
2011-05-29 01:50 UTC, Nikita Skovoroda
Bad image (this one is rendered on black background). (145 bytes, image/png)
2011-05-29 01:51 UTC, Nikita Skovoroda
orig.png (good image, this one is ok) (148 bytes, image/png)
2011-05-29 01:52 UTC, Nikita Skovoroda

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Description Nikita Skovoroda 2011-05-29 01:50:28 UTC
Created attachment 60424 [details]
Screenshot of the bug.

Version:           unspecified (using Devel) 
OS:                Linux

Reproducible: Always

Steps to Reproduce:
0) You should be using light color scheme, default one is good.
1) Download the two provided images, place them in some (new) folder.
2) Open them in gwenview, KolourPaint, or any other image viewer. Confirm that they are equal.
3) Open dolphin with image previews turned on, go to that folder.

Actual Results:  
Dolphin shows different images. One of them is rendered on black background, instead of transparent. See screenshot.

Expected Results:  
Two equal images, no black color.

*) That happens for Dolphin, Dolphin kpart, and the file dialog.
*) KDE 4.6.3 on two different Kububtu machines was also affected.
*) optipng.png is a result of „optipng -o9“ command on orig.png.
*) That (original, good) file is a testcase created with KolourPaint. It also happens on real images with transparency (if you use optipng on them).
Comment 1 Nikita Skovoroda 2011-05-29 01:51:06 UTC
Created attachment 60425 [details]
Bad image (this one is rendered on black background).
Comment 2 Nikita Skovoroda 2011-05-29 01:52:24 UTC
Created attachment 60426 [details]
orig.png (good image, this one is ok)
Comment 3 Nikita Skovoroda 2011-05-29 01:59:22 UTC
Forgot to mention, i have KDE 4.7.beta1 on ArchLinux.

But it also happens with 4.6.3 on two different  Kubuntu machines.
Comment 4 Nikita Skovoroda 2011-05-29 02:30:35 UTC
Looks like the problem lies in image depth. Optimized images with depth 32 are ok, while with any lower depth — rendered on black background.
Comment 5 Christoph Feck 2011-06-14 13:55:13 UTC
Git commit 31f8be7ae74a5e91501fa885977d96961636d1d9 by Christoph Feck.
Committed on 14/06/2011 at 13:55.
Pushed by cfeck into branch 'master'.

Do not discard alpha component of palettized images

BUG: 274394
FIXED-IN: 4.7.0

M  +1    -1    kioslave/thumbnail/imagecreator.cpp     

Comment 6 Nikita Skovoroda 2011-06-14 23:59:21 UTC
Thank you :-).