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Bug 735463 - Canvas background disappear
Canvas background disappear
Status: RESOLVED OBSOLETE
Product: GIMP
Classification: Other
Component: User Interface
2.8.14
Other Windows
: Normal minor
: ---
Assigned To: GIMP Bugs
Jernej Simončič
Depends on:
Blocks: 736964
 
 
Reported: 2014-08-26 17:05 UTC by zeusex81
Modified: 2018-05-24 14:31 UTC
See Also:
GNOME target: ---
GNOME version: ---


Description zeusex81 2014-08-26 17:05:00 UTC 
When zooming on a big image the background disappear.
test pic : http://img110.xooimage.com/files/1/2/a/1-4751e65.png
bug screen : http://img110.xooimage.com/files/d/a/9/2-4751e70.png
Comment 1 Michael Natterer 2014-08-27 19:45:05 UTC 
I can't reproduce that on 2.8.14 on Linux.
Comment 2 zeusex81 2014-08-28 20:49:54 UTC 
Tested with the newest 2.8.14 on Windows, the bug is still here.
Comment 3 Michael Schumacher 2014-08-29 11:01:44 UTC 
Confirming. Starts to become opaque in the vicinity of (but not precisely at) suspicous powers of two, e.g. 4096 and 8192.
Comment 4 Michael Natterer 2014-08-29 19:56:06 UTC 
That must be a cairo or pixman issue. What versions are in the installer?
Comment 5 Valerio Messina 2014-09-04 16:34:03 UTC 
confirmed on GIMP 2.8.14 on Win7 64bit, using the new installer with GTK+-2.24.24
Comment 6 Simon Müller 2014-09-05 09:18:56 UTC 
Little Addition: you can "paint" whith the background by either creating a selection in one of the ares where it is missing or hovering with drawing tools. So everytime the UI is redrawn at the tools' position, the background becomes either visible or invisible. Quick video of this behavior: https://www.youtube.com/watch?v=b6S6SV3T5Bk
Comment 7 0815 2014-09-08 13:56:36 UTC 
Maybe an inconsistent alpha channel caused by a strange PNG File written by Adobe ImageReady?

PNG File can be fixed by following steps:
* Start gimp and load png. Whole background is transparent. At 1100% zoom background will be white.
* Set zoom back to 100% remove alpha channel and add alpha channel. Step for step.
* Export picture to png with default values. Problem is gone!

A diff betwwen both PNG files shows minimal difference between them.
Comment 8 Michael Natterer 2014-09-10 20:57:53 UTC 
I don't see how changing the PNG can make this bug go away. It totally
looks like a display-only issue. Of course if you remove and then add
back the alpha channel, all transparent areas will be opaque and it
doesn't happen any more. Or did I misunderstand you?
Comment 9 0815 2014-09-11 09:47:44 UTC 
Oh you're right.

A simple new picture whose background is set transparent shows the same error. So i was wrong.


Windows Paint shows a white background so I thought background is white and gimp shows at 100% zoom a false background.
Comment 10 Adrian 2016-10-03 20:53:39 UTC 
This problem still exists in 2.8.18.
Comment 11 GNOME Infrastructure Team 2018-05-24 14:31:54 UTC 
-- GitLab Migration Automatic Message --

This bug has been migrated to GNOME's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.gnome.org/GNOME/gimp/issues/576.