Hello.
Please help me understand.
When I add the DateTimeDigitized tag, I expect to see XMP-xmp:CreateDate (CIPA DC-010-2017 Exif 2.31 metadata for XMP), but I see XMP-exif:DateTimeDigitized.
I didn't find the DateTimeDigitized tag in XMP SPECIFICATION PART 1, PART 2.
Where does the XMP-exif:DateTimeDigitized tag come from in ExifTool?
Screenshot from "CIPA DC-010-2017 Exif 2.31 metadata for XMP" attached
When you write a tag with ExifTool, a tag is created with the name that you used. Writing TAGX doesn't create TAGY unless it is a special writable Composite tag or something like that.
See the XMP exif Tags documentation (https://exiftool.org/TagNames/XMP.html#exif) to learn about this namespace.
- Phil
Quote from: Phil Harvey on February 20, 2020, 07:00:50 AM
When you write a tag with ExifTool, a tag is created with the name that you used. Writing TAGX doesn't create TAGY unless it is a special writable Composite tag or something like that.
I understand that.
I expected ExifTool to write to two places, like exif (
EXIF: DateTimeDigitized) and xmp (
XMP-xmp:CreateDate), but it only wrote to xmp and with a different tag name (
XMP-exif: DateTimeDigitized).
==========================================================
f:\>exiftool -time:all= 20130730_152454.CR2
1 image files updated
f:\>exiftool -datetimedigitized="2020:02:20 15:43:59+03:00" 20130730_152454.CR2
1 image files updated
f:\>exiftool -s -G0:1 -time:all 20130730_152454.CR2
[File:System] FileModifyDate : 2020:02:20 15:46:05+03:00
[File:System] FileAccessDate : 2020:02:20 15:46:05+03:00
[File:System] FileCreateDate : 2020:02:20 15:43:59+03:00
[XMP:XMP-exif] DateTimeDigitized : 2020:02:20 15:43:59+03:00I expected:
...
[EXIF:...] DateTimeDigitized : 2020:02:20 15:43:59+03:00
[XMP:XMP-xmp] CreateDate : 2020:02:20 15:43:59+03:00==========================================================
1. I can't understand in this case why in the EXIF specification for
DateTimeDigitized exif tag maps to
xmp:CreateDate tag?
2. I didn't find the
DateTimeDigitized tag in XMP SPECIFICATION PART 1, PART 2. Where does the
XMP-exif:DateTimeDigitized tag come from in ExifTool?
3. I've had meaning to ask the yet question for a long time. Splitting tags into groups is only an internal feature for ExifTool to organize subsets of tags for easy sorting, and it is not a standard grouping?
I just want to understand some discrepancies between the specification and the ExifTool documentation and behavior.
If the exif-specification for
DateTimeDigitized had write
exif: DateTimeDigitized, then I would understand everything, but there writing
xmp:CreateDate.
Quote from: Andrei Korzhyts on February 20, 2020, 08:30:39 AM
Quote from: Phil Harvey on February 20, 2020, 07:00:50 AM
When you write a tag with ExifTool, a tag is created with the name that you used. Writing TAGX doesn't create TAGY unless it is a special writable Composite tag or something like that.
I understand that.
I expected ExifTool to write to two places, like exif (EXIF: DateTimeDigitized) and xmp (XMP-xmp:CreateDate), but it only wrote to xmp and with a different tag name (XMP-exif: DateTimeDigitized).
You seem to be expecting CreateDate to be written when you are only setting DateTimeDigitized. Either you don't really understand what I said, or I'm missing something.
You assigned DateTimeDigized, and that is the tag that was written. (Same name, not different as you mentioned.)
- Phil
Yes, there is a misunderstanding. You most likely perceive my questions in a completely different abstract dimension.
OK, help then understand what the xmp:CreateDate entry for DateTimeDigitized means in the screenshot?
Why doesn't it say, for example, exif: DateTimeDigitized?
Note that the screenshot shows and EXIF tag called "DateTimeDigitized". This is called CreateDate by ExifTool (see the ExifTool EXIF Tags documentation (https://exiftool.org/TagNames/EXIF.html)). The screenshot indicates that this EXIF tag has a corresponding tag in XMP called CreateDate.
- Phil
Quote from: Phil Harvey on February 20, 2020, 09:33:29 AM
Note that the screenshot shows and EXIF tag called "DateTimeDigitized". This is called CreateDate by ExifTool...
I don't understand here. Why does ExifTool call it "CreateDate" instead of "DateTimeDigitized"?
Quote from: Phil Harvey on February 20, 2020, 09:33:29 AM
The screenshot indicates that this EXIF tag has a corresponding tag in XMP called CreateDate.
Here I understand the same thing.
But why then ExifTool Is writing "[XMP:XMP-exif] DateTimeDigitized " instead of "[XMP:XMP-xmp] CreateDate"?
Or did I incorrectly compose a command to add the exif-tag "DateTimeDigitized" to get native "EXIF: DateTimeDigitized" instead of "XMP-exif: DateTimeDigitized"?
exiftool -datetimedigitized="2020:02:20 15:43:59+03:00" 20130730_152454.CR2
Quote from: Andrei Korzhyts on February 20, 2020, 10:20:28 AM
I don't understand here. Why does ExifTool call it "CreateDate" instead of "DateTimeDigitized"?
From the tag name documentation (https://exiftool.org/TagNames/index.html):
Note: If you are familiar with common meta-information tag names, you may find that some ExifTool tag names are different than expected. The usual reason for this is to make the tag names more consistent across different types of meta information. To determine a tag name, either consult this documentation or run exiftool -s on a file containing the information in question.
QuoteBut why then ExifTool Is writing "[XMP:XMP-exif] DateTimeDigitized " instead of "[XMP:XMP-xmp] CreateDate"?
Because you wrote DateTimeDigitized in your command:
Quoteexiftool -datetimedigitized="2020:02:20 15:43:59+03:00" 20130730_152454.CR2
- Phil
Sorry for the a lot of "stupid" questions, but it's hard for me to get into the details without seeing the full picture of the metadata world and ExifTool's place in It. I'm only just beginning to understand something in General. I have read almost all the ExifTool documentation, all the IPTC, EXIF, XMP, PLUS specifications.... The paradox is that when I read this firstly, I didn't know anything in General and so I understood everything very differently. Now, gradually, I read all this a second time with a new understanding. But I would never have thought that there are answers in what I have already read (with a different understanding at the beginning).
Metadata world — this is a big world of chaos, crutches, and problems created by the manufacturers themselves for personal purposes.
I can't understand why the specification wrote xmp:CreateDate for the XMP-version of Date Time Digitized data, but it is not used in ExifTool?
Quote from: Andrei Korzhyts on February 20, 2020, 12:18:12 PM
I can't understand why the specification wrote xmp:CreateDate for the XMP-version of Date Time Digitized data, but it is not used in ExifTool?
ExifTool has the ability to write
any available tag. It uses whatever you tell it. You just need to specify XMP:CreateDate if you want to write this tag.
- Phil
I thought ExifTool would automatically use xmp:CreateDate for the xmp-version when I assign a value for the Date Time Digitized data.
Turns out I have to control this myself to fully comply with the specification?
Quote from: Andrei Korzhyts on February 20, 2020, 01:17:31 PM
Turns out I have to control this myself to fully comply with the specification?
Yes. Or you can take advantage of the Composite MWG tags (https://exiftool.org/TagNames/MWG.html) to help with this.
- Phil
Thanks, I a bit understand.
But have yet one question.
I didn't find the DateTimeDigitized tag in XMP SPECIFICATION PART 1, PART 2.
Where does the XMP-exif:DateTimeDigitized tag come from in ExifTool?
This is official tag or not?
Quote from: Andrei Korzhyts on February 20, 2020, 02:11:27 PM
Where does the XMP-exif:DateTimeDigitized tag come from in ExifTool?
Quote from: Phil Harvey on February 20, 2020, 07:00:50 AM
See the XMP exif Tags documentation (https://exiftool.org/TagNames/XMP.html#exif) to learn about this namespace.
You don't understand me...
I think this is what the question is.
DateTimeDigitized (aka EXIF:CreateDate) is defined in the DC-008-Translation-2019-E.pdf, page 53 (https://web.archive.org/web/20190624045241if_/http://www.cipa.jp:80/std/documents/e/DC-008-Translation-2019-E.pdf#page=53) (Exchangeable image file format for digital still cameras: Exif Version 2.32).
The DC-010-2017_E.pdf, page 13 (https://web.archive.org/web/20180921145139if_/http://www.cipa.jp:80/std/documents/e/DC-010-2017_E.pdf#page=13) (Exif 2.31 metadata for XMP) states that the XMP name for DateTimeDigitized is XMP:CreateDate.
But the XMP-exif:DateTimeDigitized does not seem to be defined in that standard. The only other place DateTimeDigitized is mentioned in that doc is with regards to SubSecTimeDigitized and OffsetTimeDigitized. This seems to also apply to some of the other XMP-exif tags.
So I think the question is, What is the standard that defines the XMP-exif:DateTimeDigitized tag.
Thanks StarGeek.
I had thought the link from the Exiftool XMP-exif tags documentation was for the EXIF for XMP specification, but that is DC-010, not DC-008. I should fix this. It is true that the XMP-exif:DateTimeDigitized tag does not exist in DC-010, but it did exist in earlier versions of the XMP specification.
- Phil
Edit: No, wait. The Exiftool XMP-exif tags documentation does reference DC-010 as it should, so ignore my first two sentences. It seems that the confusion may be just because XMP-exif:DateTimeDigitized does not exist in this specification as I thought it did. But it does exist in earlier XMP specifications.
Quote from: StarGeek on February 21, 2020, 10:34:04 AM
I think this is what the question is.
DateTimeDigitized (aka EXIF:CreateDate) is defined in the DC-008-Translation-2019-E.pdf, page 53 (https://web.archive.org/web/20190624045241if_/http://www.cipa.jp:80/std/documents/e/DC-008-Translation-2019-E.pdf#page=53) (Exchangeable image file format for digital still cameras: Exif Version 2.32).
The DC-010-2017_E.pdf, page 13 (https://web.archive.org/web/20180921145139if_/http://www.cipa.jp:80/std/documents/e/DC-010-2017_E.pdf#page=13) (Exif 2.31 metadata for XMP) states that the XMP name for DateTimeDigitized is XMP:CreateDate.
But the XMP-exif:DateTimeDigitized does not seem to be defined in that standard. The only other place DateTimeDigitized is mentioned in that doc is with regards to SubSecTimeDigitized and OffsetTimeDigitized. This seems to also apply to some of the other XMP-exif tags.
So I think the question is, What is the standard that defines the XMP-exif:DateTimeDigitized tag.
YESSS!!!Thanks StarGeek. Only I didn't look at Exif 2.32, because It hasn't been approved yet (if I translated it correctly). I only watched the Exif 2.31.
Quote from: Phil Harvey on February 21, 2020, 11:01:41 AM
It seems that the confusion may be just because XMP-exif:DateTimeDigitized does not exist in this specification as I thought it did. But it does exist in earlier XMP specifications.[/i]
So this
XMP-exif:DateTimeDigitized tag is now deprecated?
It should not be used for new metadata?
Quote from: Andrei Korzhyts on February 21, 2020, 11:45:13 AM
So this XMP-exif:DateTimeDigitized tag is now deprecated?
I don't know. All I can say is that it doesn't exist in the current specification.
QuoteIt should not be used for new metadata?
I can't answer this. It depends on what you want to use it for, and what software you want to use it with.
- Phil
Hey. I have discovered that the Exif 2.32 for XMP specification draft is now available (here (http://www.cipa.jp/std/std-sec/draft_e.html)). I'll add support for this in the next release.
- Phil
Quote from: Phil Harvey on February 21, 2020, 12:17:17 PM
Hey. I have discovered that the Exif 2.32 for XMP specification draft is now available (here (http://www.cipa.jp/std/std-sec/draft_e.html)). I'll add support for this in the next release.
But this is a draft. Probably, don't need to use it. What if something changes?
Then I'll update ExifTool with the new version.
But it is unlikely that anything significant would change from this draft.
I wish more specifications were available in draft version because I often find errors in the specifications by implementing them, and it would be good to fix these before the specifications are released.
- Phil
Quote from: Phil Harvey on February 21, 2020, 11:54:17 AM
Quote from: Andrei Korzhyts on February 21, 2020, 11:45:13 AM
So this XMP-exif:DateTimeDigitized tag is now deprecated?
I don't know. All I can say is that it doesn't exist in the current specification.
QuoteIt should not be used for new metadata?
I can't answer this. It depends on what you want to use it for, and what software you want to use it with.
I use only ExifTool and latest specification (strive).
Therefore, I have a question (sorry). Why ExifTool uses
XMP-exif:DateTimeDigitized instead
XMP-xmp:CreateDate?
f:\>exiftool -time:all= 20130730_152454.CR2
1 image files updated
f:\>exiftool -datetimedigitized="2020:02:20 15:43:59+03:00" 20130730_152454.CR2
1 image files updated
f:\>exiftool -s -G0:1 -time:all 20130730_152454.CR2
[File:System] FileModifyDate : 2020:02:20 15:46:05+03:00
[File:System] FileAccessDate : 2020:02:20 15:46:05+03:00
[File:System] FileCreateDate : 2020:02:20 15:43:59+03:00
[XMP:XMP-exif] DateTimeDigitized (I expected [XMP:XMP-xmp] CreateDate in accordance with Exif 2.31) : 2020:02:20 15:43:59+03:00
I have answered this exact same question 4 times already in this thread. Please try to understand my previous answers.
Quote from: Andrei Korzhyts on February 21, 2020, 01:24:02 PM
Therefore, I have a question (sorry). Why ExifTool uses XMP-exif:DateTimeDigitized instead XMP-xmp:CreateDate?
Exiftool only does what you tell it too. It doesn't force you to use any standards. If you tell it to write to
XMP-exif:DateTimeDigitized, then it writes to that tag. To force it to write to a completely different tag is not logical.
Thanks. This phrase helped me.
Quote from: StarGeek on February 21, 2020, 01:53:57 PM
If you tell it to write to XMP-exif:DateTimeDigitized, then it writes to that tag. To force it to write to a completely different tag is not logical.
I think I understood the reason for the misunderstanding.
When I wrote
-datetimedigitized (tag name from Exiff 2.31), I meant it
-exif:datetimedigitized.
But for ExifTool it meant
-xmp:datetimedigitized (tag name from early XMP spec.).
f:\>exiftool -exif:datetimedigitized="2020:02:20 15:43:59+03:00" 20130730_152454.CR2
Warning: Sorry, exif:DateTimeDigitized doesn't exist or isn't writable
Nothing to do.I have a appeared question, why can't I write
-exif:datetimedigitized, if it meets the specification?
Ok, I'm looking here — https://exiftool.org/TagNames/EXIF.html and I see
0x9004 CreateDate string ExifIFD (called DateTimeDigitized by the EXIF spec.)Therefore, within ExifTool, I need to write
f:\>exiftool -exif:createdate="7777:02:20 15:43:59+03:00" 20130730_152454.CR2
1 image files updatedOk, I have a next appeared question why ExifTool use
CreateDate instead
DateTimeDigitized?
I'm looking here — https://exiftool.org/TagNames/index.html and I see
Note: If you are familiar with common meta-information tag names, you may find that some ExifTool tag names are different than expected. The usual reason for this is to make the tag names more consistent across different types of meta information. To determine a tag name, either consult this documentation or run exiftool -s on a file containing the information in question.Now I understand everything above.
But I'm not entirely sure that the automatic translation of this phrase is correct:
"The usual reason for this is to make the tag names more consistent across different types of meta information."I understand the General meaning, but I can't imagine a specific situation, because I didn't design ExifTool.
Is it possible to get an example?
Quote from: Andrei Korzhyts on February 21, 2020, 03:04:56 PM
"The usual reason for this is to make the tag names more consistent across different types of meta information."
I understand the General meaning, but I can't imagine a specific situation, because I didn't design ExifTool.
Is it possible to get an example?
The ExifTool EXIF tag named CreateDate corresponds to the Exiftool XMP tag named CreateDate. ie) these tags have the same purpose and the same ExifTool tag name in both EXIF and XMP = more consistent across different types of metadata.
Another way to think of it, though it may not be the original intention, is that CreateDate correlates better to the FileCreateDate. Both the file system tag and the EXIF tag basically refer to the time stamp when the file was created.
Thanks all. This topic can be finished.