Advice on which tag to use please

[Alan Clifford]

Before I commit to using a tag, I though I should ask for advice.

I am creating a directory.xmp file in all my photo album directories.   At the moment this contains two tags

datetimeoriginal, usually the date with timezone of the earliest photo in the directory and subdirectories and used for sorting

title, which eventually flows through to my website and used in two places, eg "Kenya in February" is used on http://f16.eu/2011/index.html  and http://f16.eu/2011/Kenya.February/index.html

I am thinking I'd like two fields instead of using title for both.  subject seems to be the equivalent of keywords which I might want to use later, so I am thinking that the xmp dc description tag would be the one to use, particularly as it is a lang-alt tag like the title tag.

What do you think?

Alan

[Phil Harvey]

Hi Alan,

Whenever possible it may be a good idea to use common tags such as those recommended by the MWG (see here).

Instead of XMP-exif:DateTimeOriginal, I would use XMP-photoshop:DateCreated.

Your idea of using XMP-dc:Description sounds good.  The MWG has no recommendation with respect to XMP-dc:Title, but in general I wouldn't hesitate to use the XMP-dc tags since they are all in common use, and your application sounds like a reasonable use for this.

- Phil

[Alan Clifford]

Thanks Phil.  I was wondering about the date but I am using the same one as I use in my photographs to store the date with timezone and was being consistent between the two.

Your mention of mwg leads to another question, although not relevant here because I'm using xmp, but interesting.  The mwg:datetimeoriginal includes EXIF:DateTimeOriginal as well as XMP-photoshop:DateCreated, which may not be the same as the exif one does not include the timezone.  How is that conflict resolved?

Alan

[Phil Harvey]

I know that the EXIF values are preferred.  Presumably one could use the XMP for the timezone if the time agreed with the EXIF value, but I don't recall offhand if there is a specific MWG recommendation for this.

- Phil

[Alan Clifford]

I understand now I think why I thought the timezone question important.  The MWG document has "The camera is presumably in an appropriate local time when a photograph is taken..." so, in that case, adding a timezone doesn't change the time value.

Until getting the Nikon D7000, I kept my cameras on UTC so when I add a timezone, I change the time value  as well.  That makes my two versions of the time incompatible.

Alan