On 02/04/13 16:01, Rob Z. Smith wrote: > When I look around EXIF seems to extensively support all sorts of > nonstandard or proprietary tags - just look at all the 'makertag' > stuff. I haven't noticed anywhere in the manual where the actual dt > XIF tag structure is documented but that doesn't surprise me at all. > I see 100s of Pentax maker_tags that aren't defined in the Pentax > manuals either, and I'm sure the same goes for all/some/most other > manufacturers as well. With dt being open source though we do at > least have the option of looking in the code if we are really that > bothered (although there may be a more easily accessible definition > file lying around somewhere). > > The pairing of image and .xmp sidecar file is I think the mechanism > used for storing of processing history in SOURCE files so that the > source file, particularly when a raw file, does not have to be > altered. When a new output file is generated that is an entirely > different thing, and it is then that dt history stack is included in > the output file tags, whether jpeg or other format. Quite why > history is included like that I don't know, I guess it is useful to > someone.
Apart from information purposes I don't see what use the history stack is once an image has been converted to anything other than RAW. The history assumes you have the original file and each operation is applied in turn. Once you have a JPEG, say, then this is no longer the case. I would think it quite hard to operate the history stack in reverse to get back to a previous version. Doesn't make any sense to me. Regards, Tony. > > Rgds, Rob. > > -----Original Message----- From: Willem Ferguson > [mailto:[email protected]] Sent: 02 April 2013 15:02 > To: [email protected] Subject: [Darktable-users] > history in exif > > I have 2 questions: 1) As far as I am aware EXIF does not allow for > writing of nonstandard data into the EXIF tag fields??? One of the > reasons for using the flexibility of XMP sidecar files. I thought > EXIF was supposed to be a standard, including a fairly rigid tag > structure, derived from TIFF? Am I mistaken? 2) Where in the manual > is this addressed? 2.2.8 refers to batch operations on selected > files? [2. Panels 2.8. Selected image(s)] Cannot find text there that > bears on this issue?? Kind regards, Willem Ferguson Am 01.04.2013 > 17:57, schrieb Alexander Wagner: > >> Hi! >> >> Recently, I learned that dt stores the processing history in the >> exif information of the created JPG. I wonder if there is also a >> procedure to recover this history from the JPG to a usable xmp-file >> for dt. Does this exist? If so, how would one do that? >> > RTFM > > (Section 2.2.8) > > > ------------------------------------------------------------------------------ > > Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. > $5K grand prize plus 10 genre and skill prizes. 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Submit your demo by > 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 > _______________________________________________ Darktable-users > mailing list [email protected] > https://lists.sourceforge.net/lists/listinfo/darktable-users > -- Tony Arnold, Tel: +44 (0) 161 275 6093 Head of IT Security, Fax: +44 (0) 705 344 3082 University of Manchester, Mob: +44 (0) 773 330 0039 Manchester M13 9PL. Email: [email protected] ------------------------------------------------------------------------------ Minimize network downtime and maximize team effectiveness. Reduce network management and security costs.Learn how to hire the most talented Cisco Certified professionals. Visit the Employer Resources Portal http://www.cisco.com/web/learning/employer_resources/index.html _______________________________________________ Darktable-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-users
