[digikam] [Bug 338753] New: Exif ImageDescription field is being used incorrectly

[DrSlony-4]

https://bugs.kde.org/show_bug.cgi?id=338753

            Bug ID: 338753
           Summary: Exif ImageDescription field is being used incorrectly
           Product: digikam
           Version: 4.2.0
          Platform: Gentoo Packages
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: Metadata
          Assignee: [hidden email]
          Reporter: [hidden email]

I had a hard time figuring out where the software chain I used in my workflow
is broken. I traced it down to digiKam using the EXIF:ImageDescription field
for the image description. While this seems perfectly fine, reading the Exif
specification reveals that the unfortunate circumstance is that this field is
actually reserved for the title!

CIPA DC- 008-Translation- 2012
" ImageDescription
A character string giving the title of the image. It is possible to be added a
comment such as "1988
company picnic" or the like. Two-byte character codes cannot be used. When a
2-byte code is
necessary, the Exif Private tag UserComment is to be used.
Tag = 270 (10E.H)
Type = ASCII
Count = Any
Default = None"

One ends up with a long image description where the title should be, and when
you use other software which stick to the spec this causes problems and more
work.

I edited the metadata like this:
http://i.imgur.com/YF5qPP7.png

exiftool -G -s -a -m -u -args apg363.tif | egrep "Description panel|Title
panel"
-EXIF:ImageDescription=Description panel..ASCII   Kolor stitching | 3 pictures
| Size: 599 x 512 | Lens: Fisheye | RMS: 2.23 | FOV: 73.76 x 49.34 ~ 28.90 |
Projection: Planar | Color: None |
-EXIF:UserComment=Description panel..ASCII   Kolor stitching | 3 pictures |
Size: 599 x 512 | Lens: Fisheye | RMS: 2.23 | FOV: 73.76 x 49.34 ~ 28.90 |
Projection: Planar | Color: None |
-XMP:ImageDescription=Description panel..ASCII   Kolor stitching | 3 pictures |
Size: 599 x 512 | Lens: Fisheye | RMS: 2.23 | FOV: 73.76 x 49.34 ~ 28.90 |
Projection: Planar | Color: None |
-XMP:Title=Title panel.
-XMP:Description=Description panel..ASCII   Kolor stitching | 3 pictures |
Size: 599 x 512 | Lens: Fisheye | RMS: 2.23 | FOV: 73.76 x 49.34 ~ 28.90 |
Projection: Planar | Color: None |
-XMP:UserComment=Description panel..ASCII   Kolor stitching | 3 pictures |
Size: 599 x 512 | Lens: Fisheye | RMS: 2.23 | FOV: 73.76 x 49.34 ~ 28.90 |
Projection: Planar | Color: None |
-IPTC:ObjectName=Title panel.
-IPTC:Caption-Abstract=Description panel..ASCII   Kolor stitching | 3 pictures
| Size: 599 x 512 | Lens: Fisheye | RMS: 2.23 | FOV: 73.76 x 49.34 ~ 28.90 |
Projection: Planar | Color: None |

As you can see, according to the spec this is wrong, as EXIF:ImageDescription
should be "Title panel."

Any chance this could be fixed in 4.3.0?

Reproducible: Always

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=338753

Gilles Caulier <[hidden email]> changed:

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--- Comment #1 from Gilles Caulier <[hidden email]> ---
As i know, we don't change anything about Exif comment management since a long
time into libkexiv2 interface (and in whole digiKam in fact)

I suspect more a bug introduced in Exiv2 shared lib. After all this lib perform
all background metadata management.

Q : what's give Exiv2 CLI tool instead to use Exiftool ?

After that, can you report this problem to Exiv2 team to check if all is right
or not. They know better all standard to use about metadata.

Gilles Caulier

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #2 from Gilles Caulier <[hidden email]> ---
In other words, you want mean that in your example you want to see :

-EXIF:ImageDescription=Title panel.

Right ?

Gilles Caulier

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #3 from Gilles Caulier <[hidden email]> ---
Reading spec :

"A character string giving the _TITLE_ of the image."

Yes, this depand how you interpret "title" here.

"... It is possible to be added a _COMMENT_ such as..."

It's clear that it can be interpreted as a comment. And i think that usual
people use Exif "Description" tags as a comment about the image.

Q : how other tools, which differentiate "Title" and "Comment" from GUI manage
this tag exactly ? For ex, Photoshop which can be considerated as a reference
here ?

Gilles Caulier

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[DrSlony-4]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #4 from DrSlony <[hidden email]> ---
LibExiv2: 0.24
LibKExiv2: 2.3.1

@ comment 1:
exiv2 -pa ~/test_images/apg363.tif | egrep "Description panel|Title panel"
Exif.Image.ImageDescription                  Ascii     168  Description panel.
Iptc.Application2.ObjectName                 String     12  Title panel.
Iptc.Application2.Caption                    String    167  Description panel.
Xmp.tiff.ImageDescription                    LangAlt     1  lang="x-default"
Description panel.
Xmp.dc.title                                 LangAlt     1  lang="x-default"
Title panel.
Xmp.dc.description                           LangAlt     1  lang="x-default"
Description panel.
Xmp.exif.UserComment                         LangAlt     1  lang="x-default"
Description panel.

I will attach the file.

@ comment 2: exactly, that is as the spec has it.

@ comment 3: I don't know what Photoshop does, I don't have it.

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[DrSlony-4]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #5 from DrSlony <[hidden email]> ---
Created attachment 88530
  --> https://bugs.kde.org/attachment.cgi?id=88530&action=edit
Image tagged by digiKam-4.2.0

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[DrSlony-4]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #6 from DrSlony <[hidden email]> ---
Reported: http://dev.exiv2.org/issues/985

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #7 from Gilles Caulier <[hidden email]> ---
Dr Slony,

What we can conclude following review by Exiv2 team from bug 985 ?

Gilles Caulier

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[DrSlony-4]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #8 from DrSlony <[hidden email]> ---
Caulier: I'm actually not sure as far as Exif.ImageDescription is concerned. I
asked Robin if he could clarify:
http://dev.exiv2.org/issues/985#note-19

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[Alan Pater]

https://bugs.kde.org/show_bug.cgi?id=338753

Alan Pater <[hidden email]> changed:

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--- Comment #9 from Alan Pater <[hidden email]> ---
Robin Mills over at exiv2 concluded that Adobe applications DO NOT USE the
Exif.ImageDescription field. For Title Adobe uses: xmp.dc.title.

MWG (Metadata Working Group) guidelines map Exif ImageDescription, IPTC
Caption, and XMP (dc:description) together as "Description: the textual
description of a resource's content. Also known as "user comment”, "caption”,
"abstract” or "description”."

i vote for following the MWG guidelines.

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[Gilles Caulier-4]

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--- Comment #10 from Gilles Caulier <[hidden email]> ---
Alan,

This is how digiKam work currently now (following MWG rules), or i missing
something ?

Gilles Caulier

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[Alan Pater]

https://bugs.kde.org/show_bug.cgi?id=338753

--- Comment #11 from Alan Pater <[hidden email]> ---
Yes, agreed. Digikam is following the MWG guidlines.

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=338753

Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED
   Version Fixed In|                            |4.9.0

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