Bug 139152 - Exporting Image or Drawing to PNG is missing metadata, doesn't match target resolution
Summary: Exporting Image or Drawing to PNG is missing metadata, doesn't match target r...
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: LibreOffice (show other bugs)
(earliest affected) release
Hardware: All All
: medium normal
Assignee: Not Assigned
Keywords: bibisected, bisected, regression
Depends on:
Blocks: Graphics-Export Image-DPI
  Show dependency treegraph
Reported: 2020-12-22 12:53 UTC by Telesto
Modified: 2023-07-19 16:35 UTC (History)
4 users (show)

See Also:
Crash report or crash signature:

Bibisect log (2.88 KB, text/plain)
2020-12-22 13:13 UTC, Telesto

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Description Telesto 2020-12-22 12:53:41 UTC
Exporting Image or Drawing to PNG doesn't insert DPI resolution with Skia (previously OpenGL). Working with GDI

Steps to Reproduce:
1. Open attachment 168385 [details]
2. Select the shape
3. File -> Export
4. Pick PNG and enter a file name
5. Set DPI to 222 cm/or inch (does not matter)
6. Export
7. Open the file with Gimp or another image viewer.. notice dpi missing

Actual Results:
No dpi inside the file (also not totally sure about the resolution)

Expected Results:
Should be the case

Reproducible: Always

User Profile Reset: No

Additional Info:
Version: (x64)
Build ID: 315c7570c4a72f4c834086082825533b1e50d1bf
CPU threads: 4; OS: Windows 6.3 Build 9600; UI render: default; VCL: win
Locale: nl-NL (nl_NL); UI: en-US
Calc: CL
Comment 1 Telesto 2020-12-22 13:13:02 UTC
Created attachment 168409 [details]
Bibisect log

Bisected to:
author	Tomaž Vajngerl <tomaz.vajngerl@collabora.co.uk>	2019-02-15 13:14:32 +0100
committer	Tomaž Vajngerl <quikee@gmail.com>	2019-04-03 11:57:08 +0200
commit 86ea64f216819696cd86d1926aff0a138ace2baf (patch)
tree db513803abc9dc255d27c0f08cba6d6d0c9ef1d9
parent 994b41a6c69d20637dcb95894c385f5c0102d600 (diff)
Support for native 32bit Bitmap in VCL and SVP (cairo) backend
This adds basic support for 32bit bitmaps for the SVP backend. For 
other backends the support is disabled for now as we need to add it for 
each backend separately and enable support.

When this patch is applied it is possible to a Bitmap with bit count 
32, but currently no input filter uses this with the exception of the 
new PngImageReader(libpng based), which is used only for the icons.

For a general support more things need to be implemented and tested:
- conversion back and fourth between 32-bit and 24-bit + 8bit alpha (or 
other supported pairs) 
- 'raw' export of the bitmap needs to be handeled properly (like in
SVM import/export) so it creates the correct image.
- input filters need to be checked and converted if this is necessary
- look for possible bugs when drawing transparent bitmaps
- check of UNO API


-> This is only about lacking dpi. The resolution is a mess too. Should be somewhere in the close area of the identified commit here
Comment 2 Telesto 2020-12-22 13:14:54 UTC
Conformation of this can be found in bug 132959. Setting to NEW
Comment 3 Telesto 2020-12-22 13:17:30 UTC
Adding CC: to Tomaž Vajngerl
Comment 4 Telesto 2020-12-23 09:08:59 UTC
I think lots of issue are coming from here.. Compare Export results from Master with 6.2 (running OpenGL). I think it's also relevant for transparency topic [but not sure of course]
Comment 5 Luboš Luňák 2021-01-04 17:45:43 UTC
Not Skia specific, using KF5 and Gtk3 backends has the same problem.

*** This bug has been marked as a duplicate of bug 132959 ***
Comment 6 Stéphane Guillou (stragu) 2023-07-19 16:35:41 UTC
Setting this 6.3 regression back to New to keep it separate from the older issue in bug 132959.

For the record, I followed a similar process as Teleto, on Linux and with Draw:

1. Open attachment 168385 [details]
2. File > Export > as PNG, make sure it uses 96 DPI
3. Open file in GIMP, look at metadata in Image > Image Properties

Alternatively, with command line:
1. convert the file:
instdir/program/soffice --headless --convert-to png star.odg

2. Use ImageMagick's command line tool "identify" to see missing metadata:
identify -verbose star.png | head -10

Resolution is at 72 ppi.
Resolution, print size and units are missing from identify output.

96 ppi and useful metadata.

Present in recent master buid at 24.2 alpha as well as Not in, so it's a regression.

Bibisected with linux-64-6.3 bibisect repo to first bad commit e36ad95ea54fcef5b6b97de27a7e8843b78b9e1b which points to core commit:

commit 86ea64f216819696cd86d1926aff0a138ace2baf
author	Tomaž Vajngerl Fri Feb 15 13:14:32 2019 +0100
committer	Tomaž Vajngerl Wed Apr 03 11:57:08 2019 +0200
Support for native 32bit Bitmap in VCL and SVP (cairo) backend
Reviewed-on: https://gerrit.libreoffice.org/69289

Tomaž, can you please have a look?