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 ImageEn Library for Delphi, C++ and .Net
 ImageEn and IEvolution Support Forum
 EXIF, IPTC & XMP Data
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shackers

United Kingdom
17 Posts

Posted - Oct 11 2020 :  14:46:48  Show Profile  Reply
I wish to extract certain key data from image files such as author/creator, date created, title etc.

I can see there are the following possibilities just for the author/creator:
EXIF_Artist
EXIF_XPAuthor
XMP_DC_Creator
IPTC_PS_Writer

I note that the IPTC spec also has a creator tag. Haven't worked out how to access these various tags yet.

Is it possible to find data stored for all these tags?

If so, which is to be preferred and is there any simple method of choosing the right one or have you got to work with them all to make sure you extract relevant data?

xequte

5607 Posts

Posted - Oct 11 2020 :  16:34:04  Show Profile  Reply
Hi

We don't aggregate meta-data because the purposes of each type differs, e.g. EXIF for technical data from camera images, IPTC to provide information when image sharing, etc.

Although there is a lot of overlap, which information you should use will depend on your application.

To see all the available meta-data, try the following demos in the \InputOutput\ folder:

\EXIF\
\IPTC\
\XMP\
\DICOM\


Nigel
Xequte Software
www.imageen.com
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shackers

United Kingdom
17 Posts

Posted - Oct 14 2020 :  03:31:50  Show Profile  Reply
I can see there are 31 constant values for Photoshop IPTC and that I can access these with calls such as:

ImageEnIO1.Params.ReadIPTCField(PhotoShop_IPTC_Records, IPTC_PS_Keywords);

The demo appears to deal only with the photoshop constants.

I can't see how I access any other IPTC fields or are there no other IPTC felds?

The schema at https://www.iptc.org/std/photometadata/documentation/userguide/#field-reference-table lists various core fields that are not within the photoshop tags and also numerous extensions. Is it possible to access these using ImageEn and, if so, how?
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shackers

United Kingdom
17 Posts

Posted - Oct 14 2020 :  12:19:18  Show Profile  Reply
I have found the specification document for IPTC it is here:

https://www.iptc.org/std/IIM/4.1/specification/IIMV4.1.pdf

"Subject Reference" is shown as "2:12".

I assume that to access it I would just call ReadIPTCField as follows:

s:=ReadIPTCField(2, 12);
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xequte

5607 Posts

Posted - Oct 14 2020 :  22:12:29  Show Profile  Reply
No, that doesn't seem like a valid dataset index.

Please try this updated IPTC demo which shows a raw view of all fields in an image:

attach/xequte/20201014221225_IPTCDemo2.zip
33.38 KB

Nigel
Xequte Software
www.imageen.com
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