IFD0 Description Field

[grole]

I was editing captions recently using the ACDSee "description" field under the IPTC section, which appears to write data not only to IPTC caption-abstract, but also XMP Description.

After mixing up the caption with another file (of the same name) and correcting it, I noticed that the incorrect caption was still saved in a field called IFD0 Description.

Can someone explain why this might have happened, and if I should be avoiding it? ACDSee shows the right caption: the one in IPTC and XMP. So no problem there.

Thanks

[StarGeek]

It sounds like ACDSee is following the Media Work Group (MWG) recommendations for reconciling the various tag groups (EXIF, IPTC, and XMP).  Exiftool can also do this by using the MWG composite tags.  That page also has info for further research.

To avoid it, you could either just write things through ACDSee or use the MWG tags to keep things in sync.  Or just ignore or remove the ImageDescription tags as you prefer.

[grole]

Thanks for the explanation. I just emptied the caption and keywords using ACDSee and re-wrote them. Now I still have the IFD0 caption, but it is the same as the iptc caption I entered.

Is there any way to empty only the IFD0 field? (just in case I need to in the future)

This brings me to another question: I've been adding captions and keywords specifically to the IPTC fields as I've understood (and also experienced) that these fields are the ones generally read by applications. For example Google Photos, or Picasa before it, appear to look at these fields when displaying captions. I assume that this convention will remain, and therefore I've been maintaining them. Generally I'm using Lightroom for this (with the "write metadata to file" option enabled) and recently ACDSee for modifiying some older photos. Both seem to write to IPTC and XMP at the same time.

Is this a good strategy? Or should I be doing something differently/additionally to ensure caption visibility and prevent loss/rework in the future?

Thanks!

[Phil Harvey]

Is there any way to empty only the IFD0 field? (just in case I need to in the future)

You mean IFD0 ImageDescription?: exiftool -ifd0:imagedescription= FILE

This brings me to another question: I've been adding captions and keywords specifically to the IPTC fields as I've understood (and also experienced) that these fields are the ones generally read by applications. For example Google Photos, or Picasa before it, appear to look at these fields when displaying captions. I assume that this convention will remain, and therefore I've been maintaining them. Generally I'm using Lightroom for this (with the "write metadata to file" option enabled) and recently ACDSee for modifiying some older photos. Both seem to write to IPTC and XMP at the same time.

Is this a good strategy? Or should I be doing something differently/additionally to ensure caption visibility and prevent loss/rework in the future?

I think that the old IPTC may fade away eventually in favour of XMP.  Personally, I would delete all IPTC and write XMP only.

- Phil

[StarGeek]

My strategy revolves around what my tools can deal with.  ImageDescription I clear out, because none of my tools (other than Exiftool) can read it or edit it directly.  They write to it like it's an afterthought.  So as part of one of my batch files, I have a command that compares it to Caption-Abstract (or Description, can't remember which offhand) and if they're the same, it's removed.  Otherwise it's flagged for further research.

Right now, I'd really prefer to move completely to XMP.  But my favorite image viewing tool, Irfanview, doesn't handle XMP data.  If I want quickly view an image and take a quick look at the metadata, I have to keep XMP and IPTC synced, otherwise I'd have to open up the file in a more intensive program.  So for now, I keep them synced.  If I find a tool that has simple viewing ability and lets me read xmp metadata without an extended interface or long startup time, I'll probably start dumping the IPTC data.

Personally, since the tools you're using (LR, ACDSee) keep things synced normally when you write the data through them, I'd suggest looking at the Media Work Group tags when writing tags with exiftool.   So if you want to change the description, you would write to -MWG:Description and it would change XMP:Description, IPTC:Caption-Abstract, and EXIF:ImageDescription all at once.

[grole]

@Phil, thanks for the command and tip about xmp. I never considered it but I suppose most applications look at XMP, either in addition to IPTC or instead of it (example: google photos) when displaying captions. ACDSee has a specific section in the metadata called IPTC, so I assumed this was the only area being written to. There is no specific XMP area in ACDSee, and Lightroom doesn't specify what set it's fields are written to. Anyway I suppose if I continue using LR to write captions, they will be stored in both and there is probably no drawback to that for now, and if anything changes exiftool will fix them up for me.

@Stargeek, also thanks for your views. Good tip to use MWG for editing. That reminds me of the metadata for mp3 files and their different groups -> some players reading one set and some the others. It took me years to find software which writes to all fields at once! (tagscanner).

Also thanks for the reply to my other post. In conclusion I'll continue writing them as I've done, but keep the MWG trick in mind and watch for irregularities as I go.

[StarGeek]

ACDSee has a specific section in the metadata called IPTC, so I assumed this was the only area being written to. There is no specific XMP area in ACDSee, and Lightroom doesn't specify what set it's fields are written to.

It is confusing.  There's the IPTC IIM (or IPTC Legacy), which Exiftool writes as the IPTC group.  Then the newer IPTC standard (IPTC Core and IPTC Extension) which follow the XMP structure, which Exiftool writes to XMP group.  When programs such as LR say IPTC, they actually mean IPTC Core, not IPTC IIM, though they're writing to both when they can.

If you check the sticky posts in this subforum, you'll find a couple of posts (Program Metadata to TAG translation, Windows metadata) where I've done some testing on what tags get written to and read from in Lightroom and Windows.  I keep planning on expanding this for a lot more programs, but haven't gotten around to it yet.

[grole]

That's great to know. Indeed it is complicated and I keep learning more. I just learned, for example, that this IFD0 tag is actually the EXIF one!

I can confirm that ACDSee 10 also writes to the same fields as LR. It can be configured to show IPTC: Caption-abstract and EXIF: ImageDescription, but not XMP: Description, although all fields are written and as far as I can tell, the other two fields are updated as soon as one is edited.

Strangely, some files I worked on a few days ago (with ACDSee) are not showing anyting in EXIF: ImageDescription according to Exiftool, although ACDSee does. This is why I thought it was an anomly. But it might have had something to do with ACDSee's treatment of my removable drive, which I've now solved.