IPTC data revisited

[Sivakatirswami]

Ian Wood wrote:
> 
> On 19 Jul 2007, at 21:55, Sivakatirswami wrote:
> 
>> Sivakatirswami wrote:
>>> I asked this once a couple of years ago, I will ask again: has
>>> anyone tackled reading and writing IPTC data to and from a JPEG?
>> 
>> I should add to this "XMP" data... as that's what Adobe seems to be
>>  using now.
> 
> I was about to suggest XMP, given that it's basically an XML file. I
>  don't know if EXIFTools can do anything with IPTC data?


right, XMP, it's just XML... but where does it live? You refer to "file"
In Adobe Bridge you edit the files in the IPTC core and there is no 
display of the XMP
structure as such...So one presumes XMP is a storage
wrapper only.

OK so I did that for one JPEG-- added a caption in the IPTC core 
description field
  as display in Bridge, moved to another photo, came back to another 
photo went
back to the original, caption was there, quit Bridge, then reopened bridge
and my caption survived... so where is it?

  I Opened the raw file in an editor and see the usual binary garble but 
no XML in the
header anywhere. I remember once doing this years ago with
some files and you could see the data as plain ASCII somewhere
inside all that binary data.

This is probably the wrong forum to talk about this... but
I was just wondering if anyone had already built tools to
"talk" to the metadata "part" of jpg files.