[digikam] [Bug 376721] New: Poor quality colour management in Preview vs Editor

classic Classic list List threaded Threaded
4 messages Options
Reply | Threaded
Open this post in threaded view
|

[digikam] [Bug 376721] New: Poor quality colour management in Preview vs Editor

bugzilla_noreply
https://bugs.kde.org/show_bug.cgi?id=376721

            Bug ID: 376721
           Summary: Poor quality colour management in Preview vs Editor
           Product: digikam
           Version: 5.4.0
          Platform: Other
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: ColorManagement
          Assignee: [hidden email]
          Reporter: [hidden email]
  Target Milestone: ---

Background:
digikam 5.4.0-2 from Arch Linux packages.
My colour-management settings:
enabled
working = BestRGB
Monitor profile = specified an ICC file generated from displayCal
Use colour-managed view in editor: enabled
Use colour-managed view for previews and thumbnails: enabled
Advanced: Use black-point; perceptual

Problem:
I am working with the image http://misc.sty.nu/IMGP0431_1-large_v1.tiff (21MB)
which uses the ProPhotoRGB-linear profile.

In the preview it looks utterly ghastly, with massively quantized shadow areas.
See http://misc.sty.nu/digikam-screenshot-preview.png 

However, in the editor it looks fine:
http://misc.sty.nu/digikam-screenshot-editor.png  (I used the "keep" option on
opening, so there remains a ProPhotoRGB->monitor-space transformation in place
to display this.)

This inaccuracy in the preview makes it difficult to compare/rate images that
rely on shadow zones in ProPhotoRGB-linear space.

I have tried varying the colour-management Advanced settings and no combination
of blackpoint compensation nor rendering intent makes it go away - and some
look even worse.

The problem does go away when I convert the image to sRGB, but changing now
would be premature in the workflow - there are lots of blends and edits pending
in multiple utilities yet.

I would understand if it was my monitor calibration profile being low quality,
but how come the editor can get it right, so why can't the preview show the
same thing?

--
You are receiving this mail because:
You are the assignee for the bug.
Reply | Threaded
Open this post in threaded view
|

[digikam] [Bug 376721] Poor quality colour management in Preview vs Editor

bugzilla_noreply
https://bugs.kde.org/show_bug.cgi?id=376721

Maik Qualmann <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[hidden email]

--- Comment #1 from Maik Qualmann <[hidden email]> ---
Your image has 14 bits. The preview load for speed reasons images only in 8
bits. The Image Editor can load 16 bits images.

Maik

--
You are receiving this mail because:
You are the assignee for the bug.
Reply | Threaded
Open this post in threaded view
|

[digikam] [Bug 376721] Poor quality colour management in Preview vs Editor

bugzilla_noreply
In reply to this post by bugzilla_noreply
https://bugs.kde.org/show_bug.cgi?id=376721

Maik Qualmann <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Latest Commit|                            |https://commits.kde.org/dig
                   |                            |ikam/0ca4c66af71b2364d69d28
                   |                            |cdff4e5364e42db28a
   Version Fixed In|                            |5.5.0
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #2 from Maik Qualmann <[hidden email]> ---
Git commit 0ca4c66af71b2364d69d28cdff4e5364e42db28a by Maik Qualmann.
Committed on 24/02/2017 at 20:29.
Pushed by mqualmann into branch 'master'.

make it possible to disable converting preview image to 8 bits
FIXED-IN: 5.5.0

M  +2    -1    NEWS
M  +2    -0    libs/settings/applicationsettings.cpp
M  +1    -0    libs/settings/applicationsettings_p.cpp
M  +1    -0    libs/settings/applicationsettings_p.h
M  +6    -4    libs/threadimageio/previewsettings.cpp
M  +2    -2    libs/threadimageio/previewsettings.h
M  +4    -1    libs/threadimageio/previewtask.cpp
M  +20   -12   utilities/setup/album/setupalbumview.cpp

https://commits.kde.org/digikam/0ca4c66af71b2364d69d28cdff4e5364e42db28a

--
You are receiving this mail because:
You are the assignee for the bug.
Reply | Threaded
Open this post in threaded view
|

[digikam] [Bug 376721] Poor quality colour management in Preview vs Editor

bugzilla_noreply
In reply to this post by bugzilla_noreply
https://bugs.kde.org/show_bug.cgi?id=376721

--- Comment #3 from Tim <[hidden email]> ---
Many thanks!

--
You are receiving this mail because:
You are the assignee for the bug.