kofa
April 26, 2023, 7:42am
25
See
opened 10:44PM - 27 Oct 21 UTC
closed 12:16AM - 24 Apr 23 UTC
no-issue-activity
**Describe the bug/issue**
I've found out that the export module has extremely … inconsistent performance when exporting JPGs.
As you can see in the attached pictures below, simply changing the "set size in pixel" values in export module generates very erratic (and unusable) results.
What makes it bad is that the output at full resolution is also bad.
Thus far, I could obtain (apparently) decent JPG image only setting the pixel size to 3840x3840.
Full resolution and HD (1920x1920) settings give very bad results.
Disabling OpenCL (in "preferences -> gpu/cpu/memory) doesn't solve the issue, but produces differently looking damaged results.
**To Reproduce**
_Please provide detailed steps to reproduce the behaviour, for example:_
1. Set different values in the "set size in pixel" fields in the export module in the light table
2. The result has a chance to come out "broken"
**Expected behavior**
Only the resolution should be different (resized image), but the output should be still consistently looking.
**Screenshots**
This one looks reasonable (size set to 3840x3840)
But at full resolution it looks terrible:
(adding link, file too big) [Trentino_estate_2021_0459_dt.jpg](https://mega.nz/file/Rhl2nCgT#PUc5waQRGozkaZS4GKhrOx7vlED5lFVh9qY4IWuX7A0)
Setting to 1920x1920 also looks terrible:
Same as previous, but with OpenCL disabled:
**Platform**
_Please fill as much information as possible in the list given below. Please state "unknown" where you do not know the answer and remove any sections that are not applicable _
* darktable version : 3.6.1-1.1
* OS : Linux - kernel 5.4.0-89-generic
* Linux - Distro : e.g. Ubuntu 20.04.3
* Memory : 32 GB
* Graphics card : NVIDIA GeForce GTX 1050 Ti
* Graphics driver : nvidia-driver-460 (proprietary)
* OpenCL installed : yes
* OpenCL activated : yes
* Xorg :
* Desktop : Gnome
* GTK+ :
* gcc :
* cflags :
* CMAKE_BUILD_TYPE :
**Additional context**
The raw file is [this](https://mega.nz/file/Uk82zYwS#xCRlZj6lmkyY6oPH4R5poR_ks9biqNSbgRJxDyx6x7E).
The [XML file](https://mega.nz/file/wp9AgayT#w7nCeDZgwsqqcD7i8JPmzxrL3ZVswaRsoyAcogabWhw) (identical development settings for all the jog above, only difference in the export module, pixel size, and OpenCL disabled in the last).
EDIT: forgot to mention, discussion also going on [here](https://discuss.pixls.us/t/darktable-export-bug-photo-changes-depending-on-pixel-size/27610?u=billznn) (apparently I'm not the only one affected; one reported also for ver 3.7).
anddarktable zoom artefacts in darkroom (and Preview window artefacts due to low quality resampling · Issue #10899 · darktable-org/darktable · GitHub )
The preview (in darkroom) is generated using the same code path as when export is scaled down, and high quality resampling is disabled. That is done for performance reasons. Sometimes, one has to zoom in to 100%.
And there are others, where the reason is not known (no dehaze, issue is visible without resizing / at 100% preview, some can reproduce, others cannot). An example is Darkroom view of processed raw image looks different from that of exported image · Issue #11741 · darktable-org/darktable · GitHub .
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