Bug 105380 - Black/Write 25% and 75% mso color modes are mapped to black/white 50% in LibreOffice
Summary: Black/Write 25% and 75% mso color modes are mapped to black/white 50% in Libr...
Status: RESOLVED DUPLICATE of bug 89928
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
Version:
(earliest affected)
Inherited From OOo
Hardware: All All
: low minor
Assignee: Not Assigned
URL:
Whiteboard:
Keywords: filter:pptx
Depends on:
Blocks: PPTX-Images
  Show dependency treegraph
 
Reported: 2017-01-17 02:24 UTC by Haleh Alemasoom
Modified: 2021-05-10 14:07 UTC (History)
5 users (show)

See Also:
Crash report or crash signature:


Attachments
photo of logo color changed after opening in libreoffice + original slide (538.85 KB, patch)
2017-01-17 02:24 UTC, Haleh Alemasoom
Details
pptx document (530.72 KB, application/vnd.openxmlformats-officedocument.presentationml.presentation)
2017-01-17 09:39 UTC, Xisco Faulí
Details
comparison (56.02 KB, image/png)
2017-01-17 09:39 UTC, Xisco Faulí
Details

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Description Haleh Alemasoom 2017-01-17 02:24:49 UTC
Created attachment 130487 [details]
photo of logo color changed after opening in libreoffice + original slide

Logo color changed after openning a pptx document in Libreoffice. please see the attachment. The original log is all white, but the Libreoffice one is half black half white.
Comment 1 Cor Nouws 2017-01-17 09:02:32 UTC Comment hidden (obsolete)
Comment 2 Cor Nouws 2017-01-17 09:09:22 UTC Comment hidden (obsolete)
Comment 3 Xisco Faulí 2017-01-17 09:38:17 UTC
Confirmed in

Version: 5.4.0.0.alpha0+
Build ID: 36afb355ac37122d32d624db079def123ef548a2
CPU Threads: 4; OS Version: Linux 4.8; UI Render: default; VCL: gtk3; 
Locale: ca-ES (ca_ES.UTF-8); Calc: group

and

LibreOffice 3.3.0 
OOO330m19 (Build:6)
tag libreoffice-3.3.0.4
Comment 4 Xisco Faulí 2017-01-17 09:39:00 UTC
Created attachment 130490 [details]
pptx document
Comment 5 Xisco Faulí 2017-01-17 09:39:35 UTC
Created attachment 130491 [details]
comparison
Comment 6 Timur 2017-01-17 11:26:52 UTC
This is slide master with PNG images.
It's obvious MSO and LO are different, but if you open .pptx as .zip and there \ppt\media\image2.png, you'll see that original Gainsight PNG has color changed, just like on http://www.gainsight.com/. 
So, I'd say that LO preview is better. Or MSO prevents effects, because they are none, and displays simple image. 
I update the title but I cannot confirm this as a bug. Please mark as Resolved-NotaBug or wait until someone explains why this is a bug. 

PS after I wrote that and before submitted, Xisco confirmed, but I disagree again, triage is not proper.
Comment 7 Tomaz Vajngerl 2017-01-17 12:35:23 UTC
Hm.. the image is converted to B&W and it looks like the threshold what color is black and what is white is different between MSO and LO.

Changing the threshold to match MSO is an option but that would be a regression for existing documents. A solution is to convert it to B&W bitmap using MSO compatible threshold in the input filter but only if image is different.. maybe. 
This solution would cause a loss down the road, because the original image would be replaced, but at least the reproduction would be exact.

I'm not sure if this is worth the effort, but at least we could document somewhere that the difference exists.

Tomaž
Comment 8 Timur 2017-01-17 12:42:43 UTC
In my non-export view, solution as explained is not required and I propose this be marked as NotaBug, after "document somewhere" is precised.
Compatibility pages in Help should be proper, I guess.
Comment 9 QA Administrators 2019-03-17 03:51:47 UTC Comment hidden (obsolete)
Comment 10 Xisco Faulí 2019-10-01 15:48:13 UTC
The problem is that the image uses as color mode 'black & white 25%' which is translated to 'black & white 50%' in LibreOffice
Comment 11 Xisco Faulí 2019-10-01 16:28:54 UTC
We don't take into account a value like <a:biLevel thresh="25000"/>
Starting point: https://opengrok.libreoffice.org/xref/core/oox/source/drawingml/fillproperties.cxx?r=09cd0e36#750
Comment 12 Xisco Faulí 2019-10-02 10:18:01 UTC
the value 128 is passed hardcoded to BitmapMonochromeFilter in https://opengrok.libreoffice.org/xref/core/vcl/source/gdi/bitmap3.cxx?r=f93a345a#253, changing it to 64 is like using 25% black/white
Comment 13 Xisco Faulí 2021-02-16 10:56:08 UTC
Still reproducible in

Version: 7.2.0.0.alpha0+ / LibreOffice Community
Build ID: a5d68a4f959804f93ddda61a45cedaadb504e3f2
CPU threads: 4; OS: Linux 5.7; UI render: default; VCL: gtk3
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded
Comment 14 NISZ LibreOffice Team 2021-05-10 14:07:58 UTC
This has the same b/w 25% effect applied on the image as bug #89928

*** This bug has been marked as a duplicate of bug 89928 ***