IPTC handling and limits
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Hello and thanks for your work.
I'm new to digikam and IPTC. My understanding is that . "tags" in digikam may be stored as IPTC keywords (i.e. in the IPTC "Keyword" field). . this field is 64 byte wide and can only store full ASCII characters . IPTC has many other fieds (such as location, ...) which can be hand-edited by a kipi plugin (through the Image menu). My questions are : . is this correct ? . when I save my digikam tags as IPTC metadata : how can I be sure I don't overflow the header size ? What happens if I do (does the flag name gets truncated ?) . does it make sense to have a digikam tag representing the picture location since it will be saved in the keyword header, instead of in the maybe more appropriate location IPTC header ? Thank you. _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
Re: IPTC handling and limits
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2007/9/12, Thomas Hummel <[hidden email]>: Hello and thanks for your work. yes . this field is 64 byte wide and can only store full ASCII characters yes . IPTC has many other fieds (such as location, ...) which can be hand-edited yes Note : XMP support is under developpement and will be available for next release 0.10.0 (KDE4). XMP remplace IPTC-IIM. All these limits will disapears : UTF-8, no size restriction, etc. kipi-plugin to edit metadata will be updated of course. My questions are : yes, it's truncated automaticly by Exiv2 library. . does it make sense to have a digikam tag representing the picture location What do you mean by picture _location_ ? Regards _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
Re: IPTC handling and limits
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On 9/12/07, Gilles Caulier <[hidden email]> wrote:
> > > 2007/9/12, Thomas Hummel <[hidden email]>: > > . does it make sense to have a digikam tag representing the picture > location > > since it will be saved in the keyword header, instead of in the maybe > more > > appropriate location IPTC header ? > > What do you mean by picture _location_ ? I think what Thomas is asking is, does it make sense to use a tag/keyword to denote the pictures location when there is a field specific to location in the IPTC specification? Just my interpretation. -- Jay Dickon Glanville _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
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In reply to this post by Gilles Caulier-4
On Wed, Sep 12, 2007 at 12:43:12PM -0400, Gilles Caulier wrote:
> . this field is 64 byte wide and can only store full ASCII characters > > > yes > But I read somewhere that keyword is a multi-value field, so the 64B limit is only for one keyword but I can have unlimited number of keyword. Is that true ? To be clear, if in digikam I assign, for a picture the following flags : people/family/thomas people/family/laurence animals/cats/timi ... can I have any number of those saved in IPTC keywords as long as each of them (such as people/family/thomas) is less then 64B long ? > Note : XMP support is under developpement and will be available for next > release 0.10.0 (KDE4). XMP remplace IPTC-IIM. > > All these limits will disapears : UTF-8, no size restriction, etc. > kipi-plugin to edit metadata will be updated of course. Quite interesting indeed. Will there be some way to migrate existing IPTC flags or should I wait (since I 'm only begining to use tagging (so it may not be too late for me) ? > yes, it's truncated automaticly by Exiv2 library. Ok, what about accents (I think I put some in tag names before knowing it wasn't supported) : are they skipped ? > What do you mean by picture _location_ ? My idead was to assign a tag representing the place the picture was taken (the city, ...). But I thought that maybe it's right place was in the location related IPTC fields, rather than into a keyword field which just "emulate" the former. > Regards Thanks for your answers and your wonderful efforts! _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
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In reply to this post by Jay Dickon Glanville
On Wed, Sep 12, 2007 at 01:06:59PM -0400, Jay Dickon Glanville wrote:
> I think what Thomas is asking is, does it make sense to use a > tag/keyword to denote the pictures location when there is a field > specific to location in the IPTC specification? Exactly. Knowing that tags are handeled inside digikam but the location IPTC field can, to my knowledge, "just" be edited by hand through kipi plugin. Which would lead to the dilemma : easy handling through tags vs coherent storage in the appropriate IPTC field. _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
Re: IPTC handling and limits
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In reply to this post by Thomas Hummel-2
2007/9/12, Thomas Hummel <[hidden email]>: GillesOn Wed, Sep 12, 2007 at 12:43:12PM -0400, Gilles Caulier wrote: yes, in theory. For JPEG, the IPTC section is limited to 64Kb. for PNG and TIFF, there is no limit. To be clear, if in digikam I assign, for a picture the following flags : yes > Note : XMP support is under developpement and will be available for next all tags are stored in digiKam DB. when all will be ready in 0.10, just use the sync pictures<->DB tools to update all in your images. Of course the future right options to sync XMP must be enable (XMP config panel not yet done). > yes, it's truncated automaticly by Exiv2 library. There is a patch to support UTF-8 with IPTC-IIM, but i'm not satisfied by it because IPTC workflow is broken with others photo management software. IPTC and char encoding is infernal and badly normalized. This is why Adobe have created a new format (XMP) to remplace it. _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
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On Wed, Sep 12, 2007 at 03:24:07PM -0400, Gilles Caulier wrote:
> yes, in theory. For JPEG, the IPTC section is limited to 64Kb. for PNG and > TIFF, there is no limit. sorry if I misunderstand, but here you mean, by keyword (like one line of my exmaple below (people/family/thomas) or for the whole ? > To be clear, if in digikam I assign, for a picture the following flags : > > > > people/family/thomas > > people/family/laurence > > animals/cats/timi > > ... > > can I have any number of those saved in IPTC keywords as long as each of > > them (such as people/family/thomas) is less then 64B long ? > yes Same clarification request as above : here you mean "yes" whatever the file format (jpeg, tiff, ...) or just for some of them ? > all tags are stored in digiKam DB. when all will be ready in 0.10, just use > the sync pictures<->DB tools to update all in your images. Of course the > future right options to sync XMP must be enable (XMP config panel not yet > done). Ok, I see, but that would be an argument for creating tags with accents (UTF-8) right now, wouldn't it (so tags name are here to stay and won't need to be "accentuated" later) ? Is the patch you mention below activated by default ? To be clear : Do I have better to create right now a tag named "Françoise", in order not to rewrite "Francoise" into "Françoise" when XMP will be supported ? Or is it safer, regarding the status of char-encoding right now, to create "Francoise" and then "migrate" it later when the "ç" will be supported (but I cannot think of any easy way to do it automatically) ? Note : Char encoding is a mess by itself ...;-) _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
Re: IPTC handling and limits
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2007/9/12, Thomas Hummel <[hidden email]>:
On Wed, Sep 12, 2007 at 03:24:07PM -0400, Gilles Caulier wrote: IPTC metadata format is undependant of file format, excepted about where picture store the IPTC byte array and which size restriction is relevant. in IPTC you can store an unlimited list of keywords, of 64B each (nx64B) > all tags are stored in digiKam DB. when all will be ready in 0.10, just use the pach is not yet apply in source code. To be clear : DB store all strings in UTF-8. When you store tags as IPTC keywords, all char are converted to ascii latin1 format. You create all you tags using accents as well, but you must take a care than IPTC will not support it very well. If you is patient, XMP support will be available for 0.10 planed for KDE4 release. I don't know a simple way to patch all tags to add accents automaticly. You can certainly do it with a script which will make changes in SQlite DB file. _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
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On Wed, Sep 12, 2007 at 04:18:08PM -0400, Gilles Caulier wrote:
> IPTC metadata format is undependant of file format, excepted about where > picture store the IPTC byte array and which size restriction is relevant. > > in IPTC you can store an unlimited list of keywords, of 64B each (nx64B) Clear now, thanks, except you said above : "> > yes, in theory. For JPEG, the IPTC section is limited to 64Kb. for PNG > > and > > > TIFF, there is no limit." which imply the file format has some relevance though ? > the pach is not yet apply in source code. ok. > DB store all strings in UTF-8. ok. > When you store tags as IPTC keywords, all > char are converted to ascii latin1 format. > You create all you tags using accents as well, but you must take a care than > IPTC will not support it very well. ok, are you saying that IPTC is not only full ASCII (7bits) but is somehow iso-latin1 "compliant" (I thought IPTC would support only 7bit ASCII) ? According to what you are saying, if the "limited" support of iso-latin1 of IPTC works for me, I have better to create tags with accents in digikam since : . they would be stored internally in UTF-8 (so XMP ready) . they would "work enough" for now (stored as iso-latin1 IPTC keywords) > If you is patient, XMP support will be > available for 0.10 planed for KDE4 release. Ok. What happens then to the IPTC meta-datas one would have put into the picture file ? I guess XMP would correspond to another file area so we will end up in files containing both IPTC headers (with tags/keywords we assigned "before") AND XMP headers elsewhere in the file : is that correct ? (note : that wouldn't be a problem I guess, since we wouldn't use IPTC metadata anymore). Thanks again for the time you take to clarify thoses issues. _______________________________________________ Digikam-users mailing list [hidden email] https://mail.kde.org/mailman/listinfo/digikam-users |
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