[Bug 303170] New: Autorotate on Import should be lossless

https://bugs.kde.org/show_bug.cgi?id=303170

            Bug ID: 303170
          Severity: normal
           Version: 2.7.0
          Priority: NOR
          Assignee: [hidden email]
           Summary: Autorotate on Import should be lossless
    Classification: Unclassified
                OS: Linux
          Reporter: [hidden email]
          Hardware: openSUSE RPMs
            Status: UNCONFIRMED
         Component: Import
           Product: digikam

When "Auto-rotate/flip image" is checked on import, photos are rotated
automatically according to their EXIV tag which is fine. Unfortunately this
seems to be done in a lossy manner, meaning rotating the image and saving it
anew. This should be done using a lossless rotation instead.

Reproducible: Always

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[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=303170

--- Comment #1 from Marcel Wiesweg <[hidden email]> ---
Which image format are you referring to?

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[Gilles Caulier-4]

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Gilles Caulier <[hidden email]> changed:

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

--- Comment #2 from Gilles Caulier <[hidden email]> ---
Autorotation is performed by JPEG Loss Less methods, provided by libjpeg...

https://projects.kde.org/projects/extragear/graphics/digikam/repository/revisions/master/entry/libs/jpegutils/jpegutils.h#L84

Gilles Caulier

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--- Comment #3 from [hidden email] ---
Yes, I'm referring to JPEG. But how do you explain that those pictures are
about 20% smaller after the import? I know JPEGs can often be optimized but I
cannot explain a change from 900k to 700k...?

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--- Comment #4 from [hidden email] ---
BTW: When loading them into GIMP, setting the second image to "difference" and
boosting the curves way up, I can actually see, that there's a difference
between those two pictures. So it cannot be a lossless rotation imo.

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[Gilles Caulier-4]

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--- Comment #5 from Gilles Caulier <[hidden email]> ---
Can you share 'before' and 'after' JPEG images to check diff.

I don't know how you compare both image into gimp, but i'm sure that you need
to rotate one image to check color channel contents. Rotation can change image
color data... This can be not lossless, depending of algorithm used in
background.

The file sizes diff can become from metadata where digiKam will record
information. This operation do not touch image data !

Gilles Caulier

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[Gilles Caulier-4]

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Gilles Caulier <[hidden email]> changed:

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

--- Comment #6 from Gilles Caulier <[hidden email]> ---
Do you see my previous comment.

Without images samples it will be difficult to investigate.

Gilles Caulier

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[Gilles Caulier-4]

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Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Autorotate on Import should |Auto-rotate should be
                   |be lossless                 |loss-less while importing

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[Gilles Caulier-4]

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--- Comment #7 from Gilles Caulier <[hidden email]> ---
New digiKam 4.11.0 is available :

https://www.digikam.org/node/740

Can you reproduce the problem with this release ?

Gilles Caulier

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[Gilles Caulier-4]

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--- Comment #8 from Gilles Caulier <[hidden email]> ---
digiKam 4.12.0 is out :

https://www.digikam.org/node/741

We need a fresh feedback using this release please...
Thanks in advance.

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[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=303170

[hidden email] changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Version Fixed In|                            |5.1.0
         Resolution|WAITINGFORINFO              |WORKSFORME

--- Comment #9 from [hidden email] ---
With digiKam 5.0.0, I cannot reproduce this problem.
I close this file now. Don't hesitate to re-open if necessary.
Gilles Caulier

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