[digiKam-users] why is batch convert to bw so extremely slow? solved

[Maik Qualmann]

The BQM now uses the initial settings from the editor for the parameters to 
save images.

https://invent.kde.org/graphics/digikam/-/commit/
b6c1940f7972d5c9c2ad5db2cb61ca6d0ce398f2

Maik

Am Freitag, 3. Juli 2020, 18:13:32 CEST schrieb Daniel Bauer:
> Am 01.07.20 um 18:55 schrieb Maik Qualmann:
> > The cause is the set compression. The BQM has its own setting for
> > compression, see the "Save Images" tab. The default is 9, here with a
> > 20MB PNG it takes about 1 minute, at level 5 only 10 seconds. The
> > compression settings are also saved when you save a workflow.
> 
> Hm. I have set png compression to 5 in digikam settings
> (Bildbearbeitung -> Einstellungen speichern -> PNG Kompression)
> 
> Just to look what happens I put a jpg image in batch processor and there
> chose "convert to png", then a dialog is offered to set compression, and
> this dialog is already set to 5.
> 
> ... Just now I see:
> 
> When converting a color png to a bw png the batch processor does not
> take the settings from digikam settings, but one has to set it again
> within the batch processor under "save images" (a tab that I have never
> looked at before, just used the "rename images", because I thought the
> standard digikam settings were used)
> 
> > The Multicore setting is in the "Behavior" tab.
> 
> Ha, after desperately searching for that "Behaviour" in the digikam
> settings, I finally found it in the batch window :-)
> 
> > Maik
> 
> So, thanks. The problem is solved for me.
> 
> (Although me personally thinks that the batch processor should use the
> settings saved in the general digikam settings as default. That would be
> more logical from my point of view because usually one only opens those
> tabs of things one wants to change, and does not check again those
> settings that one believes that one has already set them...)
> 
> > Am Mittwoch, 1. Juli 2020, 17:49:23 CEST schrieb Daniel Bauer:
> >> Am 01.07.20 um 16:08 schrieb Gilles Caulier:
> >>> Hi Daniel,
> >>> 
> >>> Did you activate Multicore support in BQM ?
> >> 
> >> Hi Gilles,
> >> 
> >> where do I find that setting?
> >> 
> >>> Le mer. 1 juil. 2020 à 16:07, Daniel Bauer <linux at daniel-bauer.com> a
> > 
> > écrit :
> >>>> Am 01.07.20 um 07:42 schrieb Maik Qualmann:
> >>>>> Saving large PNG files takes so long, Gimp is not faster either. Are
> >>>>> you
> >>>>> sure you saved it as a PNG in the editor and not as a JPG? If
> >>>>> versioning is active, "Save changes" creates a JPG depending on the
> >>>>> setting, which is very fast. If you want to have a JPG in BQM, you
> >>>>> have
> >>>>> to attach the tool for saving in JPG at the end of the tools.
> >>>>> 
> >>>>> Maik
> >>>> 
> >>>> I use to work with png. The difference I see is between the batch tool
> >>>> and the edit tool. Of course, saving "save as png" takes a bit, but
> >>>> compared to the batch tool it is extremely much faster.
> >>>> 
> >>>> There is no versioning active. It reads the original png, converts to
> >>>> bw, then saves in a subfolder as png. This takes 2 to 3 minutes per
> >>>> image, which is really long.
> >>>> 
> >>>> Doing the same manually, also in digikam: in album click on image to
> >>>> open editor, color: convert to bw, save as png... is at least ten times
> >>>> faster, but needs a lot of clicks and is very boring - and ideal job
> >>>> for
> >>>> a batch process. But I had to do it manually because I didn't want to
> >>>> wait almost 3 hours...
> >>>> 
> >>>> I know that highly compressed png take more time, but in settings I
> >>>> have
> >>>> set png compression to 5, and I think, the batch process uses that
> >>>> compression, too. Or not?
> >>>> 
> >>>>> Am Dienstag, 30. Juni 2020, 20:11:56 CEST schrieb Daniel Bauer:
> >>>>>> Hi,
> >>>>>> 
> >>>>>> Sometimes I'd like to convert a complete album to bw. I added 69
> >>>>>> color
> >>>>>> png of 30-40MB to a batch, selected convert to bw, save in new
> >>>>>> folder,
> >>>>>> run.
> >>>>>> 
> >>>>>> Each image takes more tan 2 minutes to convert. When I open it in
> >>>>>> editor, and click color->bw it works immediately, also saving the
> >>>>>> file
> >>>>>> is fast. But batch processing is so slow that it cannot be used.
> >>>>>> 
> >>>>>> Now I must go through the album in editor, click
> >>>>>> color->bw->save->next
> >>>>>> 68 times, which is not comfortable but at least 10 times faster :-(
> >>>>>> 
> >>>>>> Why?
> >>>> 
> >>>> --
> >>>> Daniel Bauer photographer Basel Málaga
> >>>> https://www.patreon.com/danielbauer
> >>>> https://www.daniel-bauer.com