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Bug 712317 - "Merge down" changes bottom layer's opacity and mode
"Merge down" changes bottom layer's opacity and mode
Status: RESOLVED OBSOLETE
Product: GIMP
Classification: Other
Component: User Interface
2.8.8
Other All
: Normal normal
: ---
Assigned To: GIMP Bugs
GIMP Bugs
: 532232 (view as bug list)
Depends on:
Blocks:
 
 
Reported: 2013-11-14 16:56 UTC by Jase
Modified: 2018-05-24 14:02 UTC
See Also:
GNOME target: ---
GNOME version: ---



Description Jase 2013-11-14 16:56:26 UTC
I have looked to see if thsi is a known issue or not, and have found no other mention of it, although a similar issue is reported involving layer transformations...

Given two layers:
A (Mode Normal, Opacity 50), and
B (Mode Normal, Opacity 50);

When:
Layer A is selected and via the right click menu  in the layer dialogue, instructed to 'merge down', the reslutant layer B has Mode Normal, Opacity 100.

Objects previously drawn on layer B still reflect the previous Opacaity, and adjusting the Layer's opacity back to 50 further fades the existing items.

New objects follow the opacity 100 value, and fade correctly if the layer's opacity is altered.

From the Gimp Help FIle

"7.7. Merge Down

The Merge Down command merges the active layer with the layer just below it in the stack, taking into account the various properties of the active layer, such as its opacity and layer mode. The resulting merged layer will be in Normal mode, and will inherit the opacity of the layer below. If the layer below is not opaque, or if it is in some mode other than Normal, then this command will generally change the appearance of the image.

The most common use of Merge Down is to construct a layer, by starting with a “base layer” (usually opaque and in Normal mode, so that you can see what you are doing), and adding a “modification layer” on top of it, with whatever shape, opacity, and layer mode you need. In this case, merging down the modification layer will combine the two layers into one, without changing the way the image looks."

Unless I am missing something, current function is opposite of intention.  Lower layer is reset instead of being honored.

Ubuntu 12.04 64 bit
I-7 Processor
8 GB ram
Gimp 2.8.8 (from Ubuntu Repos)
Comment 1 Michael Schumacher 2013-11-18 23:41:25 UTC
Bug 532232 is probably related.
Comment 2 saulgoode 2014-01-31 11:15:34 UTC
It seems that the description in the Help File is incorrect. The new layer created by a merge does NOT inherit the opacity of the bottom layer.

To my knowledge, GIMP has never behaved the way described in the Help File with regard to the opacity of merged layers. If it were to do so then merging a fully opaque layer down onto a less than opaque layer would result in the opaque graphic of the top layer becoming semi-transparent. 

Furthermore, the comments in the source code (app/core/gimpimage-merge.c) describe the result as:

  /*  The final merged layer inherits the name of the bottom most layer
  *  and the resulting layer has an alpha channel whether or not the
  *  original did. Opacity is set to 100% and the MODE is set to normal.
  */
Comment 3 Michael Schumacher 2014-02-07 21:04:25 UTC
We could reassign the bug to GIMP-manual.
Comment 4 Michael Natterer 2016-11-07 18:17:40 UTC
*** Bug 532232 has been marked as a duplicate of this bug. ***
Comment 5 GNOME Infrastructure Team 2018-05-24 14:02:45 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/508.