Metadata

Who needs metadata?

All photographers, editors, image libraries and businesses handling images need metadata to keep track of the multitude of images passing their desks every day. Anyone who has struggled to find digital images on their own desktop will understand the problem to which metadata is the answer.

Digital images slip though your fingers without metadata. They can lodge in cracks and crevices in your system, or they can be lost in the vast spaces of the Internet and used by other people without permission.

What is metadata?

Information about an image

Metadata is any information about an image and can be in a number of forms. It can be hard copy, text visible on database or online, an electronic text file, or information carried within the image file.

The label on the picture

Prints and transparencies had labels stuck to the back of the print or to the frame of the transparency. In the digital world we still need the same basic information we wrote on the print  or slide mount – the 3 Cs of Caption, Credit, Copyright, and the picture number for identification. This information needs to stay with the picture, and in the digital world it can be carried within the image file in fields specified by the IPTC.

Types of metadata

Descriptive metadata holds information about the content of the image. This includes the caption, location, person shown in the image, event shown in the image, and keyword. Descriptive metadata is needed to correctly identify the content of the image, and for retrieval of images online.

Administrative metadata is used to keep track of the image as it passes through the workflow. This can include job identifier, instructions, date created, and contact information for photographers and suppliers.

Rights metadata is information about copyright, model release, property release, underlying copyrights (eg of artworks shown in the image) and licensing.

Metadata formats

Metadata can be entered in XMP format by a photographer or publisher, but it can also be picked up automatically from camera data in Exif format. Date and time created, and geo-location are examples of camera data. This data can be transferred into the XMP data fields.

Metadata Schemas

A metadata schema is a way of organising data into fields (like caption, credit, photographer, location) The buzzword here is interoperability – the data I enter in my image needs to be easily read and understood by someone else down the line. Critically, in the digital age, the information must be read by other peoples’ software.

To achieve this we have metadata standards, which provide carefully defined fields of data in formats which can be read and understood by others. There are a large number of metadata schemas in existence, used across all sectors, but for photographers there are two main schemas: IPTC and PLUS.

Where is metadata held?

Metadata can be held in a number of different places, depending on the workflow adopted by you and your customers.

In the image file

Metadata embedded in the image file is used to store data and is essential for images in transit. The data can be embedded using Photoshop and Bridge, Lightroom and Aperture, Fotostation and Photomechanic and other software used by photographers and image libraries to manage images.

In Photoshop, use File/File info to reveal the IPTC panels. You can enter IPTC Core and Extension data here

Figure 1 Panel for IPTC Core fields in Photoshop CS5

Figure 2 Panel for IPTC Core fields in Photoshop CS5 (scrolled down to reveal more fields)

Figure 3 Panel for IPTC Extension fields in Photoshop CS5

Figure 4 Panel for IPTC Extension fields in Photoshop CS5 (scrolled down to reveal more fields)

In Bridge, select the metadata panel. You can enter IPTC Core data here.

Figure 5 Metadata side panel in Bridge.

The IPTC has issued IPTC –PLUS Panels for Bridge to enable both Core and Extension data to be embedded in the image file using CS3 and up. (Versions CS3 and CS4 do not show the IPTC Extension fields). The script is easily installed, is easy to use, and has a number of productivity features not found in other panels.

Figure 6 IPTC-PLUS panel for Bridge

In a database

Not all data about an image is carried in the image file. Photographers and image libraries hold data they need for their own administration which is not needed by customers. This is usually held in a database. The database is the repository for all information about an image.

Good databases will allow data embedded in images by photographers to be imported, and will export another set of data fields to customers when images are distributed or downloaded.

Transferring metadata

Metadata can be embedded in the image file, but it is also commonly transferred in the form of a spreadsheet (Excel or csv files, for example) which can be uploaded into a database.

The advantage of using the IPTC defined fields for transferring data is that the meaning is standardised, so the information is interoperable.  A spreadsheet can be created using the IPTC field labels.

When to enter metadata

The short answer is, add it as soon as you can in the workflow. Some data from the shoot will be added in Exif format by the camera itself, and it is good to enter shoot details at the time of processing your images, in Photoshop or Lightroom. This will immediately make your images retrievable by something other than shoot date.

Your basic contact and copyright data should be held in a template and entered with a click of a button.

How to use IPTC and PLUS Fields

IPTC

The Press and Telecommunications Council was set up by the news industry to standardise information passed between news agencies and their clients. The IPTC  is the standards body for metadata carried within the image file, and the IPTC fields can be populated using Adobe Photoshop.

The IPTC information comes in two formats. The legacy format is IPTC-IIM, and is still widely used by some news agencies. The latest format is Adobe’s XMP format, which is an XML based labelling technology allowing data to be embedded in a file. If you are using CS versions of Photoshop, you enter your data in XMP format.

The IPTC Core fields were created in 2004 using Adobe’s XMP format. The fields are the same as the legacy IIM fields, and can be viewed in any version of Photoshop. There are 30 IPTC Core fields.

IPTC Extension fields were added in 2008 to extend the Core schema and avoid ambiguities. There are 46 Extension fields.

With 76 fields in total, the IPTC schema can express most information needed by a photographer working in the field.  This is not to say that a photographer needs to use all these fields; data is entered at various parts of the workflow by photographer, picture editor, image library and publisher. The photographer may enter information in just a few fields, depending on the circumstances.

Figure 7 IPTC fields list (from CEPIC/IPTC Metadata Handbook)

PLUS

The PLUS coalition has developed a set of standards for communicating and managing rights metadata. The PLUS fields can hold information on creators, licensors, models, rights offered and rights granted. The PLUS standards can be codified in machine-readable form, allowing for automated workflows.

Some of the IPTC  fields have adopted the PLUS definition, so those fields are shared by both schemas. The data is entered into the IPTC Extension field.

Why use metadata?

Copyright Protection

A digital image without metadata is an ‘orphan’. No one knows where it comes from, who owns copyright, or how to ask for permission to use the image. There are many orphaned images around, and some people think that if an image is on the internet it can be used for free.  Copyright law operates in the same way on the internet as it does for hard copy images, and permission should always be sought for use of an image.

Figure 8 Copyright symbol

You need to protect your copyright by making sure the critical data is always in the image file – and that includes low res preview images (which are just the size for use on the web!)

Workflow

The digital workflow brings productivity gains for photographers and their clients (though it may not always seem so when you are first getting to grips with the technology). This productivity can only be achieved with some functions being automated. Automation is driven by metadata; it powers images through the workflow. Picture editors view thousands of images every day, far more than they could handle in the past. Without the metadata to track and retrieve these images it would not be possible.

Your customers need metadata

The first principle of digital file handling is that functions should only be performed once. So any data that you, the photographer, create should be available to your customer.

Publishers and picture desks want to reduce the amount of data entry they do, and they rely on photographers to supply data from the shoot.  News agencies often supply a metadata template for photographers which already holds data about the shoot location and date. The photographer enters data from the shoot itself.

Picture libraries also require data. The image you supply will not be retrieved, and rights will not be sold, without the relevant data. Each agency has different requirements for metadata, depending on how they work internally.

Critical IPTC fields for photographers

Must have

IPTC Core

•  Creator (photographer name)

•  Credit Line

•  Description (Caption)

•  Copyright notice

•  Title (your filename or ID for the image)

Advisable

IPTC Core

•  Date created (can be read from Exif)

•  Keywords

•  Rights Usage Terms

IPTC Extension

•  Location created

•  Location shown (these may be different!)

•  Model release Status

•  Person Shown

Sometimes supplied by commissioning editor

IPTC Core

•  Headline

•  Job ID

IPTC Extension

•  Organisation (depicted)

•  Event (depicted)

The principles of metadata use

Write once only

Make sure the data you have written can be transferred on to other formats and other software.

Check what your customers need

If your customers’ software only views the caption field (this happens), make sure your data is collated there, but keep it in separated form in its correct field as well. (for example, a caption could read: Man taking dog for a walk; 2010; © AN Photographer)

Embed critical data in every image

Don’t let your images leave your hands without the critical 3 Cs as minimum: Caption, Credit, Copyright – and the identifying picture number. Low res preview images on the internet should be included.

Check your software doesn’t dump data

Interoperability still isn’t all it should be. Sometimes data entered in one programme is dropped in another. Be aware, and complain when it happens. Keep up the pressure on the software suppliers!

Keep data separate

Use the IPTC fields correctly for unambiguous data. If you have to collate data in the caption field, use separators, and keep it in the correctly defined fields as well. That way your images are future proofed.

IPTC Core and Extension – Q&A

How do I know which fields to use?

There are several places to go for detailed information about IPTC fields and their use.  IPTC and CEPIC (the European picture agency association) have created a guide to metadata which includes charts to help you on field use. This is available on both the IPTC and CEPIC websites. The specifications and user guides for IPTC fields can be found on the IPTC web site.

Figure 9 CEPIC/IPTC Metadata Handbook

Why are there so many fields?

It is important that each field has an unambiguous meaning, so the data is ‘granular’. This leads to a large number of fields. But you may only have to use a small number in your part of the workflow. The metadata planning chart in the IPTC/CEPIC metadata Handbook will help you see all the fields on one page. You can pick and record the fields you need at different stages of your workflow.

Why are there new Location fields in IPTC Extension?

The location field in IPTC Core (now a legacy field) did not distinguish between location of the camera (as recorded on GPS, for example)  and location of what’s shown in the image (which in some circumstances could be in another country). These two locations are now split for clarity.

What is the Supplier’s Image ID in IPTC Extension?

IPTC Core had no field for the image ID or picture number. The Title field was often used for this, but the photographer’s filename was often overwritten. The Supplier Image ID is for use by the latest supplier of an image. If the image is distributed by an agency, this is the field which should be used by the agency for its picture number or identifying ID. The photographer picture number can be placed in the Title field. If the photographer is the last supplier of the image, then their image number also should be recorded in the Supplier Image ID field.

What’s the difference between Supplier’s Image ID and Image Supplier ID?

The first refers to the ID for the image (the picture number) while the second refers to the Identifying ID for the supplier in the PLUS or other registry.

What’s the difference between the IPTC panels and the Description panel in Photoshop?

Some of the fields are shared (you can see that if you enter data in the ‘Author’ field on the description panel, it appears in the IPTC Core ‘Creator’ field). The Description panel does not hold all the IPTC fields.

Why can’t I enter Extension field data in Bridge?

Bridge only shows the IPTC Core data in the panel on the left hand side. To access Extension data, control (or command)-click will give you the option to view File Info for the image, where you can see use the IPTC Extension panel. The other way to do it is to use the IPTC-PLUS Metadata Panel for Bridge.