Metadata is “data about data”. While the term is used to cover a wide variety of fields, the one that most interests me is metadata used in digital images.
The most prevalent standard for digital image metadata is Exif, implemented in every digital camera. It’s metadata focused on technical information about the picture itself: camera shutter speed, exposure, etc. The standards of IPTC-IIM and XMP are focused on metadata about the subject of the photograph: topic, location, photographer, etc. IPTC-IIM is an earlier standard that has been in use by the press agencies since the 1980s – so there’s a large installed base. However, it’s not easily extensible. Enter XMP, which is XML-based, first created by Adobe Systems Inc. in 2001. In 2004, Adobe got together with the IPTC organisation and others to create the “IPTC Core” standard, an XML-based successor to IPTC-IIM.
Of course, as the old joke has it, “the great thing about standards is that there are so many to choose from”. What is worse, is that different manufacturers (of cameras, application software, operating system software) interpret the standards in subtly different ways so that the resulting implementations are often incompatible with each other.
This got to such a stage that in 2006, Microsoft proposed the setting up of a cross-industry working group to deal with the matter. As a result, the Metadata Working Group was created in 2007 by five founding members: Apple, Adobe, Canon, Microsoft and Nokia. In 2008, Sony joined the party. The goals are:
- Preservation and seamless interoperability of digital image metadata.
- Interoperability and availability to all applications, devices, and services.
Not before time, I hear you cry. Certainly I get very frustrated by the current lack of interoperability that exists.
Yesterday, at the annual Photokina exhibition, the Metadata Working Group released version 1.0 of their Guidelines for Handling Image Metadata. In the Group’s own words, “this document describes how best to use existing standards such as Exif, IPTC, and XMP to address the key organizational metadata questions that most consumers have”.
I’ve only had time to quickly glance through the document, but it does seem to be a good effort to attempt to herd the bunch of cats that are software developers – many of them in their own companies.
It was with some irony that I noted this paragraph (page 32):
Hierarchical keywords are not covered. However it’s well understood that this is an important use case even in the context of the consumer and will be added to future versions of this document. There are existing solutions available e.g. Adobe Bridge, Adobe Lightroom as well as Microsoft Expression Media and Windows Live Photo Gallery that have introduced hierarchical keyword workflows specific to their needs.
Irony, because it’s the way that Microsoft’s Windows Live Photo Gallery has currently implemented hierarchical keywords that is causing me some interoperability problems and frustration at the moment.
Oh well, back to herding cats…