Being ready for the future?

[Schubi]

Hello Phil,

First off - thank you very much for an 'easy to use' and excellent written tool. I've downloaded the latest version of 'exiftool' and it runs quick and smoothly under OSX 10.6.

Over the last days I've been reading a lot about metadata and the different existing (or actually non-existing) standards. The following picture initially helped me to understand why things are so messed up:




I've decided to run through all of my JPG photos of the last 15 years and to tag them with basic data - either directly with a specific field or with the help of the keywords. My personal list so far:

• Description
• Year, Month
• Country, CountryCode, City

Whilst reading through the forums here I get the feeling that XMP is the future - but even if that's true then it still might take years until camera producers and software makers change their standards and applications.

What would you personally recommend doing now in order to be prepared for the future? Using MWG to synchronise EXIF, XMP and IPTC to be on the safe side? Any recommended fields that I definitely should populate?

Thanks

[Phil Harvey]

For maximum compatibility I recommend using the exiftool MWG Tags.

These tags handle the synchronization issues by following the MWG recommendations.

There aren't any required tags that I would suggest always writing, but if you want to write something it is best to use the MWG tags if possible.

- Phil

[Schubi]

Thanks Phil. I did some tests with the MWG tags but now I'm not sure how exactly MWG tagging works. Please see my example below.


JPG photo with all XMP, EXIF, IPTC and MarkerNotes removed...
[user@ ~] exiftool -G0 Desktop/TEST/20101001_223034.jpg
   [ExifTool]      ExifTool Version Number         : 8.45
   [File]          File Name                       : 20101001_223034.jpg
   [File]          Directory                       : Desktop/TEST
   [File]          File Size                       : 1467 kB
   [File]          File Modification Date/Time     : 2011:01:15 15:45:28+08:00
   [File]          File Permissions                : rw-r--r--
   [File]          File Type                       : JPEG
   [File]          MIME Type                       : image/jpeg
   [File]          Image Width                     : 2816
   [File]          Image Height                    : 2112
   [File]          Encoding Process                : Baseline DCT, Huffman coding
   [File]          Bits Per Sample                 : 8
   [File]          Color Components                : 3
   [File]          Y Cb Cr Sub Sampling            : YCbCr4:2:2 (2 1)
   [Composite]     Image Size                      : 2816x2112


Tagging the photo...
[user@ ~] exiftool -mwg:country="China" -mwg:city="Shanghai" -mwg:keywords="2010" -mwg:keywords="October" -mwg:keywords="CHN" -mwg:keywords="China" -overwrite_original -ext JPG 20101001_223034.jpg
    1 image files updated


Checking the photo again...
[user@ ~] exiftool -G0 20101001_223034.jpg
   [ExifTool]      ExifTool Version Number         : 8.45
   [File]          File Name                       : 20101001_223034.jpg
   [File]          Directory                       : Desktop/TEST
   [File]          File Size                       : 1470 kB
   [File]          File Modification Date/Time     : 2011:01:15 15:47:23+08:00
   [File]          File Permissions                : rw-r--r--
   [File]          File Type                       : JPEG
   [File]          MIME Type                       : image/jpeg
   [File]          Image Width                     : 2816
   [File]          Image Height                    : 2112
   [File]          Encoding Process                : Baseline DCT, Huffman coding
   [File]          Bits Per Sample                 : 8
   [File]          Color Components                : 3
   [File]          Y Cb Cr Sub Sampling            : YCbCr4:2:2 (2 1)
   [XMP]           XMP Toolkit                     : Image::ExifTool 8.45
   [XMP]           Subject                         : 2010, October, CHN, China
   [XMP]           City                            : Shanghai
   [XMP]           Country                         : China
   [Composite]     Image Size                      : 2816x2112


So 'exiftool' tells me that the information was only written to XMP - where I would have thought that some information should have also gone into IPTC and EXIF... when looking at the corresponding MWG tags on this page. Interestingly the information shows up within IPTC when importing the photo into 'Aperture 3.1.1'.





Even more confusing to me is that the MWG page states that "IPTC information is written only if the original file contained IPTC." However, I removed all IPTC data via 'exiftool' before tagging via MWG.


Mind shedding some light into this? Thanks a lot!

[Phil Harvey]

Yes, this is confusing because the new IPTC core specification actually uses the XMP format!  What ExifTool calls "IPTC" is the original "IPTC/NAA IIM" standard.

- Phil

[chrisn]

Hi Phil, Schubi,

I thought I had some understanding of IPTC and Exif data, but this has got me totally confused. I can appreciate the comment about using MWG tags if that is what the working group are recommending, but do allow as many programs to read the data as possible do I have to fill in the values for each type of tag? ie

EXIF:Artist
IPTC:By-line
XMP-dc:Creator
CurrentIPTCDigest
IPTCDigest

Or is Exiftool smart enough to recognise it has been given a value for one of these and use it in all cases?

Chris

[Phil Harvey]

Hi Chris,

ExifTool lets you do whatever you want.

The ExifTool MWG plug-in is special in that it imposes the MWG recommendations when reading tags.  If you extract the MWG tag, it will be smart enough to take the "recommended" version of the tag if it exists in multiple locations.

- Phil