Bug 307452

Summary:	Corrupt preview images at 30 bit depth
Product:	[Applications] digikam	Reporter:	kdebug1
Component:	Thumbs-Image	Assignee:	Digikam Developers <digikam-bugs-null>
Status:	RESOLVED DOWNSTREAM
Severity:	major	CC:	caulier.gilles
Priority:	NOR
Version:	2.9.0
Target Milestone:	---
Platform:	openSUSE
OS:	Linux
Latest Commit:		Version Fixed In:	7.6.0
Sentry Crash Report:

Description kdebug1 2012-09-26 18:40:43 UTC

Using NVidia Card with 30 bit depth causes thumbnail images to be displayed in corrupted colors.
Double clicking a thumbnail to enable the preview component shows correct preview but the thumbnail line remains oddly colored

Reproducible: Always

Steps to Reproduce:
1. 30 bit depth desktop
2. start digikam
3.
Actual Results:  
see above

Expected Results:  
correct colors

Comment 1 caulier.gilles 2012-09-26 20:51:33 UTC

There is nothing relevant of screen device managed by digiKam. All is delegate to Qt API and screen sub system, including NV driver...

I suspect a problem in NV driver in your case with Qt...

Note : if i understand well your report, only thumbnails are broken, not full screen preview. Right ?

Gilles Caulier

Comment 2 kdebug1 2012-09-28 18:11:20 UTC

Exactly. Thumbnails are broken, but the preview in the lower row is not.

Fullscreen is untested yet, will try it soon and report.

Comment 3 caulier.gilles 2012-09-28 21:17:41 UTC

Ca

Comment 4 caulier.gilles 2012-09-28 21:18:31 UTC

Can you take a screenshot of thumbnail view ?

Can you provide a 30 bits sample image to test here ?

Gilles Caulier

Comment 5 Marcel Wiesweg 2012-09-29 11:11:19 UTC

Gilles, this is about hardware capabilities, 10bits per channel:
http://forums.dpreview.com/forums/read.asp?forum=1004&message=40619494

We generate pixmaps from QImages, there is no other way, which only supports 8bit, and probably the whole traditional 2D X.org stack only support 8bit.

Digikam will not in the near future be based on SceneGraph, but OpenGL seems to be the only way to access this bit depth.
http://stackoverflow.com/questions/6172514/display-monitors-with-more-than-256-shades-of-gray

For the bug here, I suspect a problem in the graphics stack.

Comment 6 caulier.gilles 2012-09-29 12:13:03 UTC

Right Marcel,

So this bug cannot be resolved to digiKam. This problem must be reported in another place, as video card driver company, or on X11 project if opensource driver is used...

Gilles Caulier