META 101

Types of Metadata

Image files contain images, yes. But savvy photo professionals know they hold much more.

An analogy may help:
Think of a digital image file as a box.
In that box - as in a Japanese bento box - are sections or compartments.

As trays in a bento box hold several types of food, virtual compartments in image files can hold several types of data – from the pixels that make up the image to the text that identifies and describes the image.

Not all image file formats have these compartments. But JPEG, TIFF, PSD, Raw and several other file formats can include any or all the following standard types of metadata:

Often called "legacy" IPTC, this schema was developed in the early 1990s, primarily to aid news organizations in captioning early digital images. Its primary advantage is that most image editing and management programs can read and write its widely compatible fields.

IPTC Core & Extension
This newer schema builds on the legacy of IIM by adding more types of descriptive and administrative information, including new fields to accommodate the needs of the stock photography and cultural heritage communities, packaged in a more robust data format, "XMP."

The Picture Licensing Universal System for identifying and defining image-use licenses, describes a schema and tools for generating a string of characters that can identify a copyright holder, user, scope and terms of a licensed image use.

This is the newer data format used by IPTC Core and Extension for storing and accessing image metadata. It enables metadata storage within an image file or in an accompanying sidecar file, and it permits creation of custom metadata fields.

These metadata, often created by cameras and other capture devices, include technical information about an image and its capture method, such as exposure settings, capture time, GPS location information and camera model.

Dublin Core
Many image libraries and a wide variety of industries store information with image files using this schema. Several of its fields are interoperable with IPTC formats.