[digikam] [Bug 332598] New: seems to display wrong colours on TIFF files

[Christoph Anton Mitterer]

https://bugs.kde.org/show_bug.cgi?id=332598

            Bug ID: 332598
           Summary: seems to display wrong colours on TIFF files
    Classification: Unclassified
           Product: digikam
           Version: 3.5.0
          Platform: Debian unstable
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: Color Management
          Assignee: [hidden email]
          Reporter: [hidden email]

Hi.

I've attached three low res scans from some film material, made with
SilverFast... each of them was created with different color profiles.

sRGB
ECI RGB v2 ICC4
ROMM RGB (also ICC v4)

When I display these files with e.g. imagemagick or Eye of GNOME, then all
three look basically like the same (i.e. same colours) (but not with GIMP, it
seems to have the same problem:
https://bugzilla.gnome.org/show_bug.cgi?id=727038).

But when I view it in digikm, then the colors look all different, just as when
I
open them with some dumb default Windows viewer (as said, made with SilverFast)
which has no clue about color management.

Any ideas?

Cheers,
Chris.

Reproducible: Always

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[Christoph Anton Mitterer]

https://bugs.kde.org/show_bug.cgi?id=332598

--- Comment #1 from Christoph Anton Mitterer <[hidden email]> ---
Created attachment 85742
  --> https://bugs.kde.org/attachment.cgi?id=85742&action=edit
ECI v2 ICC v4

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[Christoph Anton Mitterer]

https://bugs.kde.org/show_bug.cgi?id=332598

--- Comment #2 from Christoph Anton Mitterer <[hidden email]> ---
Created attachment 85743
  --> https://bugs.kde.org/attachment.cgi?id=85743&action=edit
ROMM RGB (ICC v4)

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[Christoph Anton Mitterer]

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--- Comment #3 from Christoph Anton Mitterer <[hidden email]> ---
Created attachment 85744
  --> https://bugs.kde.org/attachment.cgi?id=85744&action=edit
sRGB (i think ICC v2)

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=332598

Gilles Caulier <[hidden email]> changed:

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                 CC|                            |[hidden email]

--- Comment #4 from Gilles Caulier <[hidden email]> ---
Can you share tiff file also using web file service please.

Gilles Caulier

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[Christoph Anton Mitterer]

https://bugs.kde.org/show_bug.cgi?id=332598

--- Comment #5 from Christoph Anton Mitterer <[hidden email]> ---
What exactly do you mean? The same files that I've attached already? To e.g.
Flickr?

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[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=332598

--- Comment #6 from Marcel Wiesweg <[hidden email]> ---
Gilles: these files have names that sound as if they were color profiles but
they are TIFFs

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[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=332598

--- Comment #7 from Marcel Wiesweg <[hidden email]> ---
Created attachment 85795
  --> https://bugs.kde.org/attachment.cgi?id=85795&action=edit
screenshot of thumbnails

Christoph: Attached are the photos as they look on my computer. ECI and sRGB
look almost the same, ROMM is slightly lighter. Which one is wrong?

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[Christoph Anton Mitterer]

https://bugs.kde.org/show_bug.cgi?id=332598

--- Comment #8 from Christoph Anton Mitterer <[hidden email]> ---
ECI/sRGB look generally very similar (I mean when the profile is "ignored") and
ROMM looks much lighter, since, AFAIU, it was made for being used with a gamma
for 1,8.

When I open the three images with e.g. eog or imagemagick,... they look all the
way as digikam/gimp displays the srgb version on my computer... which is
probably due to the fact that my ColorHUG is somehow broken and I run with sRGB
right now...

So I guess that just confirms my point, that e.g. eog/imagemagick render
correctly, while e.g. gimp/digikam render something wrong.


I made some other scans of school pictures, where one sees the effect even
better... in eog/imagemagic all three version ECI/ROMM/sRGB look really
identically... while in digikam/gimp, the ECI/sRGB look similar... but ROMM RGB
looks just weird... all colours far too staurated, etc.

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[Christoph Anton Mitterer]

https://bugs.kde.org/show_bug.cgi?id=332598

--- Comment #9 from Christoph Anton Mitterer <[hidden email]> ---
Yeah... well... maybe I have to take everything back O:-)

Uhm I found out in the meantime, that imagemagick's display seem to not support
color profiles at all (except, showing their names)... and eog seems to only
support them for JPEG, but not for TIFF.
This eventually tricked me to believe that digikam/gimp were wrong, but maybe/I
guess they're not.

Now I've created a new set of scan's with silverfast:
http://christoph.anton.mitterer.name/tmp/public/1e7337c4-b9a1-11e3-9385-502690aa641f/c/
The readme tells which file is scanned with which parameters...

Something strange happens now:

The files that I've scanned with the Epson scanner profile,...
=> look all the same in programs that DO (I guess) support color profiles (like
digikam)
=> look way different in programs that DON'T support color profiles

The files that I've scanned with NO scanner profile,...
=> look all the same in programs that DON'T (I guess) support color profiles
=> look way different in programs that DO support color profiles

Okay I don't understand that behaviour... but at least it seems digikam is
right.
Also, looking at these test images:
http://www.color.org/version4html.xalter
seems to show, that color support in digikam is working (and I've converted
them to TIFF as well, and there it works too).

Please confirm that behaviour and then we can close the bug as invalid I guess.

Cheers,
Chris.

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=332598

Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
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             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #10 from Gilles Caulier <[hidden email]> ---
I can confirm this behavior using your image collection. I use also CM here...

Gilles Caulier

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