[Digikam-devel] Non-destructive image editing

Andi Clemens andi.clemens at gmx.net
Fri Jul 17 08:28:55 BST 2009


On Friday 17 July 2009 07:48:03 Gilles Caulier wrote:
> 2009/7/17 Gilles Caulier <caulier.gilles at gmail.com>:
> > Le 15 juillet 2009 13:44, Jean-Michel Pouré<jm at poure.com> a écrit :
> >> Dear friends,
> >>
> >> At Kdenlive.org, we are still very impressed by showfo quality.
> >
> > Thanks.
> >
> >> We would
> >> like a solution that would allow to use showfo in conjunction with MLT.
> >>
> >> We thought of a feature that may interest you:
> >> non-destructive photo correction
> >>
> >> In video, Kdenlive works as such :
> >> * The source video is left unchanged.
> >> * During video editing, Kdenlive processes the video using the MLT
> >> syntax. The film is previewed without modifying the source.
> >> * Video is exported only during final rendering.
> >
> > This also done like this in digiKam. Image is loaded in memory and
> > each action on image is stored in queue of ONG files as cache. Until
> > end, original is not touched, if you overwrite original of course.
> >
> > But in photo management, this is not non-destructive photo editing
> > exactly...
> >
> >> One drawback of image manipulation programs like Gimp or Showfoto is
> >> that they modify the original image.
>
> Until you save image no.
>
> There is 2 way to apply non-destructive photo editing :
>
> 1 save resulting images in a queue of tmp file (PNG is the best
> format) and register this queue to database .In digiKam GUI, use can
> see a preview of each version and choose the right in workflow.
> Problem is space consuming, but it's fast.
>
> 2 register in database and in image metadata (XMP media management
> namespace) all actions in editor (Actions List). When image is save,
> only list is recorded : in this case space is preserved, but time to
> restore image can be long because we need to replay all registered
> actions in editor.
>
> There is 2 bugzilla entries about these subjects :
>
> https://bugs.kde.org/show_bug.cgi?id=142056
>
> https://bugs.kde.org/show_bug.cgi?id=125387
>
> >> Of course, you can duplicate images but it is a loss of space.
> >>
> >> So the idea is to ask MLT to process photos.
>
> We have already a dedicated framework in digiKam named DImg...
>
> >> The beauty is it would possible, in theory to store MLT processing
> >> syntax in PNG tags. This would make a completely non-destructive
> >> solution.
>
> Use XMP MM namespace. No need to re-invent the wheel. PNG support
> metadata. Look Exiv2 project for details...
>
> >> Only when exporting to third-party on-line solutions or DVDs the photos
> >> would be processed. But the source would remain.
> >>
> >> MLT is very reliable and quite easy to implement. You would only need to
> >> implement plugins in MLT and load your effects. Then modify showfoto to
> >> use MLT. It would require layers to showfoto. But it is probably a
> >> needed feature.
>
> This require to break a lots of parts in digiKam. We will never do it
> (:=)))). It's a lots of work, and regression test to do.

I would even say it will break everything :-)

Andi

>
> Best
>
> Gilles Caulier
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