I’ve been asked by someone for some detail on how I tag my digital photos. I thought that it might possibly be of some interest to others, so here’s the answer as a blog entry.
The starting point is that I tag my photos using some (but by no means all) of the data elements specified by the IPTC Core standard. The following table lists the elements that I use; the descriptions that I have provided are drawn from the excellent Field Guide provided by the PhotoMetadata.org web site.
|Title||This field is a shorthand reference for the image or “photograph” – primarily for identification. The title of an image should be a short, human-readable name – text and/or numeric reference – and may take several forms.In my case, I now use a date/timestamp to uniquely identify all my photos, i.e. a title has the form: yyyymmdd-hhss-nn.|
|Description||The Description field, often referred to by applications as “Caption,” should report the who, what and why of what the photograph depicts.I don’t always follow the guideline given by the Field Guide’s explanation, I usually just rely on the fact that this metadata is covered by the Keyword and Location metadata content for my image:”If there is a person or people in the image, this caption might include their names, and/or their roles in any action taking place. If the image depicts a location, then it should describe the location. Don’t forget to also include this same “geographical” information in the appropriate fields (location, city, state/province, country) of the IPTC Core. The amount of detail to include depends on the image and whether it is documentary or conceptual”.|
|Keyword||Terms or phrases to describe the subject of content in the photograph. I have cobbled together a controlled vocabulary (see later) for my own use here.|
|Copyright Notice||The Copyright Notice should include any legal language required to claim intellectual property. It should identify the photograph’s current holder(s).|
|Rights Usage Terms||The Rights Usage Terms field should include free-text instructions on how the photograph can be legally used. The majority of my photos are licensed under a Creative Commons license.|
|Contact Info||The Contact Info fields provide a generic structure for storing basic information that should make it easy to reach the person or organization that created this image.Note: “City,” “State” and “Country” used in Contact Info should not be confused with fields bearing the same names that refer to the picture’s origin.
Since I’m not a commercial photographer, I use the bare minimum here: just city, country, email and web site.
|The full name of the country pictured in the photograph. This field is at the first level of a top-down geographical hierarchy. Use a verbal name and not a code.|
|The name of the subregion of a country – usually referred to as either a State or Province – pictured in the image. Since the abbreviation for a State or Province may be unknown to those viewing your metadata internationally, consider using the full spelling of the name. Province/State is at the second level of a top-down geographical hierarchy.|
|The name of the city where the image was captured. If there is no city, I use the Sublocation field alone to specify where the photograph was made. City is at the third level of a top-down geographical hierarchy.|
|The name of the sublocation shown in the image. This might be the name of a specific area within a city (Manhattan), or the name of a well-known place (Pyramids of Giza), monument or natural feature outside a city (Grand Canyon). Location is the most specific term, at the fourth level of a top-down geographical hierarchy.|
You’ll notice that in the above table, the location fields of ITPC Core (country, state/province, city, sublocation) are marked as legacy. That’s because there’s a newer IPTC specification (IPTC Extension) that seeks to remove the ambiguity implicit in the term “location”. After all, does it refer to the location of the camera, or the location of the subject in the picture? So the Extension defines two classes of location: the location where the image was created, and the location shown in the image itself.
For the moment, I’m continuing to use these legacy terms from IPTC Core (and for the most part, the location of the camera and the subject are the same for all practical purposes as far as I’m concerned). At some point in the future though, I’ll probably move over to using these newer metadata items from the IPTC Extension.
One other thing, I “echo” the content of the location metadata back to a structured Keyword entry. For example, a photo taken in the Dam Square in Amsterdam will have the following items of metadata in it:
Sublocation: Dam Square
Keyword: Netherlands/Noord-Holland/Amsterdam/Dam Square
This is handled automatically by the application I use in my digital workflow: IDimager. (Note: IDimager is no longer available. Its successor is Photo Supreme, which I am now using) When I tag an image with a known sublocation, then the other corresponding location metadata, as well as the structured Keyword entry are automatically written into the image. Having a structured keyword echoing the location metadata in this way helps when the images are viewed as a collection using an application that does not support IPTC location metadata, but does support IPTC keywords. Windows Live Photo Gallery, for example (but see Note 1 below).
Keywords and Controlled Vocabularies
Choosing the right set and structure of your keywords that are used in your image library is a big topic, so I can only scratch the surface here. I’ve borrowed ideas from a number of different sources to come up with mine.
First of all, I followed the excellent set of guidelines that David Riecks put together on his Controlled Vocabulary web site. Then, having a flat list of thousands of keywords is not very useful, it’s much better to arrange them into a hierarchy that connects related terms together; a so-called Controlled Vocabulary. For example, my keyword cows is actually part of a hierarchy that starts Nature/Animals/livestock/cattle/dairy cattle/cows. That way, when I search for photos (using either Windows Live Photo Gallery or IDimager) with the keyword cows, it will just show me those with cows in them. But if I search for photos with the keyword livestock, it will show me photos of cows, horses, pigs, sheep, and so on. When I use IDimager to tag a image of a cow with the cows keyword, it will automatically add all the parent keywords in the structure: dairy cattle, cattle, livestock, Animals, and Nature.
My hierarchy has been built up from a number of sources:
- The sample of David Rieck’s Controlled Vocabulary that ships with IDimager,
- Elements from the Getty Art & Architecture Thesaurus,
- My own additions and modifications.
I’ve ended up with a structure that has the following items at the root:
Each of these splits down into further categories as necessary as you go down the levels. For example, Activities splits into
- Physical and mental activities
- Processes and techniques
So then a photo of a tennis match would have the structured keyword of Activities/physical and mental activities/games/sports/ball game/tennis assigned to it.
While setting up a controlled vocabulary takes a bit of work, and it will require ongoing “gardening”, there’s no question but that it’s useful when you have a lot of photos. I’ve currently got in excess of 37,000 photos in my collection and having them all with metadata makes it much easier to manage them.
Note 1: Since I wrote this post, there has been a new version of Windows Live Photo Gallery released that does actually use the IPTC “Location created” metadata. It uses those fields to hold what it calls “geotags”, but which are in fact textual descriptions of the geographic location: street address, city, state/province and country.