Bug 318351 - SCHEMA : implement generic region tagging of image
Summary: SCHEMA : implement generic region tagging of image
Alias: None
Product: digikam
Classification: Unclassified
Component: Database-Schema (show other bugs)
Version: 3.1.0
Platform: Other All
: NOR wishlist with 10 votes (vote)
Target Milestone: ---
Assignee: Digikam Developers
: 271829 (view as bug list)
Depends on:
Reported: 2013-04-14 15:52 UTC by Christoph Anton Mitterer
Modified: 2016-06-12 03:01 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In:


Note You need to log in before you can comment on or make changes to this bug.
Description Christoph Anton Mitterer 2013-04-14 15:52:05 UTC

Digikam already provides the following two:
- normal tags
Seem to apply to the whole image and are therefore rather suited for "global" information like "macro shot" or "vacation" or "birthday picture".
Ideally less for things like "in Rome" cause in an ideal world, this would be automatically determined by perfectly set GeoLocation tags.
It's not possible to associate these tags with a region of the image.

- face tags
To mark peoples faces with a rectangular field typically associated with their name.

What I would need in addition was general tags associated with an area of the image, ideally not only rectangular areas but any polygon. And of course any arbitrary text of any length to be associated with it.
Ideally one could enable HTML (or well some HTML elements) in them so that one can e.g. mark buildings and set the corresponding link to the Wikipedia Article.
Have a look at what Flickr allows and what I do e.g. here: https://secure.flickr.com/photos/calestyo/5892335742/in/set-72157627095137796 (you need to move the mouse over the image and its fields).
There you also see why just rectangles are problematic.

Eventually I think all this should be unified and generalised or well at least the face tags and those I propose here.
Not sure if there is already and Exif/XMP/etc way to express such things, if not one should make a custom one.


Reproducible: Always
Comment 1 Christoph Anton Mitterer 2013-04-14 17:34:09 UTC
Obviously, a further nice feature would be, that such marker/tag regions are exported to to targets that support it, e.g. Flickr.

The text should then be copied 1:1 and if (like in the case of Flickr) Polygons were not supported as regions, one should perhaps simply use the rectangle that spans across the whole polygon.
Comment 2 Marcel Wiesweg 2013-04-18 19:48:30 UTC
MWG guidance provides an XMP standard for the metadata part. IIRC, rectangles and circles.
Comment 3 Christoph Anton Mitterer 2013-04-18 20:17:05 UTC
I guess http://www.metadataworkinggroup.org/pdf/mwg_guidance.pdf Section 5.9 applies here, further specified in Section C, right?

So you're right, currently there's only Point, Circle and Rectangle...

But IMHO that's quite stupid ;-) ... and it seems the standard could be easily extended.

Anyway... does digikam already use/conform to MWG?

I just send the following mail to: technical@metadataworkinggroup.com

This originates from[0].

Currently, the specification seems to only allow regions that are made up of a single(!) area which is either of type Point, Circle or Rectangle.

This is highly limiting in two ways:

1) Only one area might be specified, but in a picture or video it can easily happen that a given object (say a building) that should be marked with a region is crossed by some other object (e.g a bridge in the front of it).
So you have two not connected areas which should belong to the same region.

2) Most natural objects won't be rectangles or circles; the specification should be extended to allow arbitrary polygons to be used as areas.

Note, implementing (1) won't automatically solve (2), because such a polygon area should IMHO _not_ be defined as a list of the current Point area type - this would make it impossible to have a list of points (which might also be reasonable), thus there should be really a separate type.


[0] https://bugs.kde.org/show_bug.cgi?id=318351
Comment 4 Marcel Wiesweg 2013-04-21 13:16:01 UTC
no...did not exist when we implemented faces three years ago
Comment 5 Christoph Anton Mitterer 2014-04-06 16:22:44 UTC

So any plans here?

Especially in the fields to
- unify tags and face tags ... using the MWG syntax
- to extend the MWG syntax to allow arbitrary polygons as fields.

The later should be easily doable by having something like
mwg-rs:Type = digikam-polygon
mwg-rs:Area = x1,y1 x2,y2, x3,y3 ; xa,ya xb,yb, xc,yc

Using digikam:polygon we don't interfere with their standard's namespace too much and allows us to automatically convert to something standard conformant (should that ever be defined).
And the area example here gives two polygons (here triangles) given by their coordinates.

Comment 6 Christoph Anton Mitterer 2014-04-06 16:23:32 UTC
Oh but I think it would still make sense of course, to implement the already existing MWG area types as well... things like rectangles and circles are already enough for many cases (like face tags).
Comment 7 caulier.gilles 2014-09-02 09:56:03 UTC
*** Bug 271829 has been marked as a duplicate of this bug. ***
Comment 8 bkorb 2014-09-05 00:17:37 UTC
Add self to CC list since the *3* year old enhancement request (bug 271829) was closed/dup of this.
Comment 9 Christoph Anton Mitterer 2014-09-05 00:37:58 UTC
Just adding yourself would have been enough.. o.O

Anyway,… @ Gilles...
I saw you changed this to "Database"... but I think it should really go into XMP as well, basically just as I've said in comment #5... and as said before,.. I think it would be best, if this would also replace any "specially handled" face tags.

Comment 10 Christoph Anton Mitterer 2016-06-12 03:01:39 UTC

Anything new on this? Or any chance to ever see this supported?