[Digikam-users] editing with Color Management enabled is very slow?

Elle Stone l.elle.stone at gmail.com
Wed Mar 27 12:32:05 GMT 2013

> On 3/26/13, Marcel Wiesweg <marcel.wiesweg at gmx.de> wrote:
>> So I'm puzzled as to what Desktop ICC color
>> management, and especially ICC profile management, brings to the
>> already bountiful table that is Linux color management.
> We want to support color management enabled by default, and we want it to
> "just work". There is some low-level code involved, like scanning hard coded
> file paths on Linux for profile files. This works quite ok but it feels
> "dirty", this falls into abstraction layers which IMO should be placed at a
> desktop wide layer.

Hmm, what you say is the first thing I've read about Desktop CM
profile management that makes sense. The digiKam/Krita way of scanning
for all the available profiles means I've moved most of my profiles to
where digiKam *can't* find them. The list of folders where digiKam and
Krita look is long, many of the folders are hidden, and many of these
profiles are duplicates of profiles that are in /usr/share/color/icc.
If I don't move all the profiles that I'm not currently using out of
all the folders where digiKam and Krita look, then there are too many
profiles to comfortably wade through to find the ones I want.

As an aside, Gimp justs asks the user which folder to look in whenever
you want to choose a profile for whatever purpose. It doesn't scan for
"all" profiles upon startup. The Gimp way is much simpler from my own
point of view, but probably not from everyone's point of view.

>> The X atom is still used, yes? It's the same as the _ICC_PROFILE atom?
> Yes, exactly
>> I interpreted the first bullet above to mean that colord can set the
>> _ICC_PROFILE (same as X?) atom, and the second bullet to mean that
>> other applications can (but don't have to) use dbus to query colord
>> about what profiles are available to use for what purposes.
> Yes, sounds as if digikam should be able to read it. I have personally never
> tested with colord, though. I wouldn't say it's not a problem on digikam's side.

On 3/26/13, Erik Felthauser <efelthauser at gmail.com> wrote:
>>> it appears that digiKam (a KDE/qt
>>> app) isn't aware that colord assigned a system monitor profile. Do you
>>> have Gimp (a Gnome/gtk app) on your computer? Is Gimp aware that you
>>> have a system monitor profile?
> Looking at GIMP, I see my system monitor profile in the list, and above
> this there is a checkbox 'Try to use the system monitor profile', which it
> allows me to check / enable.

The Gimp checkbox is there even if there isn't any installed system
monitor profile.

The way to tell if Gimp is really picking up the installed system
monitor profile is to open an image with a distribution of familiar
colors, preferably with an expanse of white somewhere. Then choose a
blatantly wrong profile (try ProPhoto or WideGamut) as the
Gimp/Edit/Preferences/Color Management/Monitor profile" and
alternately check and uncheck the box that says "Try to use the system
monitor profile".

If the "Try to use the system monitor profile" box is checked AND the
correct system monitor profile is really installed, then the picture
will look right even if you've chosen a blatantly wrong profile for
the Gimp Monitor profile. And unchecking the box will then show the
wrong colors. But if there *isn't* an installed system monitor profile
(or there is one and Gimp isn't finding it), then the colors will look
wrong regardless of whether "Try to use the system monitor profile" is
checked or unchecked.

> Looking at krita, I do NOT find my system monitor profile in the list to
> choose from (there appears no way to add any not in the list), and the
> checkbox above "Use system monitor profile" is greyed out and unchecked...
> Any ideas?
> I wonder if this is related: https://bugs.kde.org/show_bug.cgi?id=312153

That's a very suggestive bug report, but there are a lot of moving
parts. Your digiKam package might use LCMS1 or 2, depending on how it
was compiled, and Krita uses LCMS2. Compared to Krita 2.5, Krita 2.6
has new (and very nice) ICC profile conversion code. There's also
"slowness if color management is enabled or not enabled" plus "using
or not using colord" plus using Ubuntu (the bug report) vs using
Kubuntu (your system)".

I'm interested in testing this new CM Desktop stuff and none of it
works on my main computer. So I will try installing Kubuntu
12.10/digiKam/colord on my laptop and see if I can replicate the "slow
color management/system monitor profile not recognized" problem. Can
you tell me which specific kde/colord color management packages you
are using? Are any of the oyranos packages also installed?


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