Re: color management

[Felix Riemann <friemann svn gnome org>]

Am Donnerstag, den 02.04.2009, 08:34 +0200 schrieb Lars Tore Gustavsen:
> 
> Hello
> 
Hello

> What about having a way to visualize that color management is in use?
> Like a tiny little icon or so, that lights up when all things is well?
> And it could be greyed out if eog don’t find any profile information
> in the image.

Hmm, maybe this could be done as a plugin. Not sure though.
Another possibility could be a profile information tab in the image
properties window (e.g. showing the name of the profile, whitepoint,...)
with a line like "Applied: Yes/No".

> Here is an example picture that eog don’t colormanage because lcms
> don’t like the attached profile.
> http://www.fc-prints.de/fileadmin/daten/fcPrints_Testbild_100ppi.jpg
> 

Yes, a quick look shows that the embedded profile is so large that it
needs to be split over 5 JPEG chunks (as they have a 64kb size limit
each). This is not yet supported by eog and normaly it should ignore
such profiles. Wonder why it doesn't here...

> 
> Is color management in tiff files a planned feature?
> 

Well, actually there is some interest in extracting metadata
(ICC,EXIF,XMP) from TIFF files. But we can't do it in a clean way due to
how eog performs metadata/image loading. To make it short: TIFF is not a
streamable format (e.g. you may need to seek backwards in the data) as
eog's current metadata reading infrastructure requires it. We would need
to buffer the whole file in memory (as gdk-pixbuf's incremental loader
does it) before being able to parse it. That's out of question as that
could lead to a memory requirement in the gigabytes. Besides of that is
a TIFF pretty complex internally, although parsing that could probably
be offloaded to libtiff then.

Ideally there would be an interface in gdk-pixbuf that would allow
applications to request metadata from gdk-pixbuf so it could ask the
decoders directly for it. But I guess that's unlikely.

Felix