IPTC

This page is about the image metadata format IPTC.

References

• Wikipedia article
• The IPTC Standard on iptc.org
• IPTC Photo Metadata User Guide on iptc.org

Origin and naming of the standard

Actually, IPTC is short for "International Press Telecommunications Council", and the metadata format developed by this group originally was named "Information Interchange Model", abbreviated to IIS. But nobody seems to use the term IIS, everybody talks about the "IPTC format" or "IPTC headers". The IPTC website itself calls IIS "legacy" and has the following to say about their format:

Today, the IPTC Standard consists of two schemas – IPTC Core and IPTC Extension – which were built on the legacy of the original IPTC-IIM [...]

Usage of IPTC tags

Note on this section

In this section I list those IPTC tags that I personally find interesting to use, notably because they represent fields that I used to fill in when I was still using iPhoto.

I have copied the description for each tag verbatim from the "IPTC Photo Metadata User Guide" (2017.1 version) so that I can use this as an easy-to-read reference instead of having to hunt for the individual descriptions in the user guide (which is structured in a way that is none too intuitive for my taste, and poorly linked).

iPhoto to IPTC field mapping

• iPhoto "Title" = IPTC "Headline"
• iPhoto "Comment" = IPTC "Description"
• iPhoto "Rating" = IPTC "Image Rating"
• iPhoto "Keywords" = IPTC "Keyword"

I am not using the IPTC "Title" field because it is a technical reference to the image.

Title

A short human readable reference for the image. It can be a text reference or a numeric reference, and serves primarily as an identifier. The Title field has often been used by photographers for the image filename, but IPTC now provides specific fields for image IDs including the Supplier’s Image ID, The Digital Image GUID, and the Registry Entry fields. The Title field should not be confused with the Headline field which is a short descriptive field about the content of an image, or with the AO Title field which contains the title of the artwork or object in the the image.

BE AWARE: this field is limited by the IIM format to about 64 characters. In XMP there is effectively no character limit.

Headline

A headline is a brief synopsis or summary of the contents of the photograph. Like a news story, the Headline should grab attention, and telegraph the content of the image to the audience. Headlines need to be succinct. Leave the supporting narrative for the Description field. Do not, however, confuse the Headline term with the Title term.

BE AWARE: this field is limited by the IIM format to about 256 characters. In XMP there is effectively no character limit.

Description/Caption

The Description field, often referred to as a ‘caption’ is used to describe the who, what (and possibly where and when) and why of what is happening in the photograph. It can include people’s names, their role in the action, the location. Geographic location details should also be entered in the Location fields. The amount of detail included will depend on the image and whether the image is documentary or conceptual. Typically, editorial images come with complete caption text, while advertising images may not.

BE AWARE: this field is limited by the IIM format to about 2000 characters. In XMP there is effectively no character limit.

Keyword

Enter keywords to describe the visible and abstract content of the photograph. Keywords are in free text form, and may be single or compound terms. Keywords are descriptive words added to an image to enable search and retrieval. They describe what is visible in the image and concepts associated with the image. Keywords are expressed as a list of terms. Keywords can be single or compound terms.

Values from the controlled vocabulary IPTC Subject Codes should be placed into the “Subject Code” field.

BE AWARE: Keywords may have to be separated by commas or other separators depending on the software. This field is limited by the IIM format to about 64 characters. In XMP there is effectively no character limit.

Image Rating

Many professional photo applications have had a image rating feature for some time. These are typically shown as star ratings within a collection and are used to indicate the quality of an image; typically giving one star for entry-level photos, and reserving the higher numbered values for more special or unique images. Assigning a star rating as part of a workflow will make it easier to quickly find, sort, or filter out more valuable images from a grouping at a later point in time.

Photographers may use a method where any ‘keepers’ from an assignment are given one star during an initial review. On a second pass they may give a two-star rating to those images deemed superior, or even three stars for those that are outstanding. These values may differ from what an agency or distributor uses, so they may be overwritten or re-evaluated. Some editors recommend that you think of this as a pyramid, with a 10 to 1 ratio between each level. This method will ensure you won’t end up with too many ‘special’ photos in a collection.

To make sure you consistently apply the same image rating criteria each time, write down your rationale. Then put this text somewhere you can refer to each time you are editing.

Here is one photographer's image rating rationale as an example:

• 0 stars = record shots, or don't delete immediately (fall back images)
• 1 star = Entry level threshold achieved (in focus, exposure within reason)
• 2 stars = Best shot from each scenario or take. (usually 1 or 2 selected for every 10 shots?)
• 3 stars = Stars of the collection, have or will prep to master files or client selects
• 4 stars = Show stoppers. These are the "Best in class" or, "cream of the crop"
• 5 stars = Reserved for future use... (which means it could be used for temporary tagging)

Note that the star rating is done by the user/supplier and there is no universal standard for the rating between systems/collections.