What is metadata? And what to know about Exif and IPTC

Basically, metadata is the data that contains information about other data, such as books and magazines, movies and music, emails or messenger messages – and, of course, files. All the files you use every day contain metadata: Word and Excel documents, image files, video files, PDFs, MP3s, etc.

In most cases, metadata is subject to a strictly defined structure, a standard. This serves to improve interchangeability and, in the digital age, of course machine readability. Of course, it can make sense for larger companies or research institutions to create their own metadata structures, but then compatibility with other systems is not guaranteed.

This paper will focus primarily on the specifics of digital image and photometric data. Therefore, the following section is only for those interested and may be omitted.

General background on metadata

The prefix meta (μετά) comes from ancient Greek and indicates here that something is on a higher level. We know the prefix in this meaning also from other terms. For example, there is the meta-language (speaking about language) or the meta-knowledge, which is especially. Knowledge about knowledge gaps includes. The hierarchy is the same in our case. Metadata , in this sense, lies above the actual data. The two different levels are also referred to as the meta and object levels.

Metadata often remains hidden from us. This is in the nature of things, but can lead to the fact that when we share files or send messages, we reveal information that we did not even know was in them. Metadata is therefore collected and analyzed on a grand scale, e.g. by Internet corporations and intelligence services.

Metadata in digital photography

The metadata of digital photos can be stored within the file itself or in a so called sidecar file. However, the latter is hardly practiced anymore. Image formats such as JPEG, TIFF or WebP are container formats and thus basically suitable for the file-internal storage of metadata. Specific markers ensure that the metadata is distinguished from the actual image data. These metadata blocks are also often referred to as headers , since they are usually stored “at the top” of a file.

What are the formats for photo metadata?

For digital photos, there are several standards that coexist: Exif, IPTC-IIM and XMP. For all three applies that it is exactly defined which data fields are valid and how the data is stored.
[Addendum: Since 2024, the C2PA standard for provenance metadata has also been established. More on this here].

We start with the Exif format. It is in use since 1995 and still relevant, especially for technical documentation.

Exif

The Exif standard was developed by the Japanese camera industry. The abbreviation stands for Exchangeable Image File Format. Exif is supported by almost every digital camera and smartphone nowadays. Most of the data is automatically generated and written to the appropriate files when the camera is triggered. Information that can be captured within the Exif data fields includes:

• • Recording time: date, time (to the second)
  • Focal length
  • Camera model
  • Aperture
  • Shutter speed
  • ISO value
  • GPS data: current position (geo-coordinates), direction of view and movement, speed, etc.

In total, the number of different data fields is in the hundreds, but usually only a small part of them is actually used. Exif also has a few non-technical data fields like ImageDescription or Copyright, which can be labeled afterwards.
The other two formats are more for manual documentation of image content. Both are also briefly presented here.

IPTC Information Interchange Model

IPTC is the abbreviation for a group of experts who developed the standard in the early 1990s (International Press Telecommunications Council). The technical implementation was carried out using the IPTC Information Interchange Model, or IPTC-IIM for short. This is considered obsolete. That is why IPTC data fields are mostly included in image files today using the improved XMP format.

Only a few image formats fully support the old IPTC-IIM standard. The most important ones are JPEG and TIFF. As mentioned, the IPTC data is mainly used for content indexing. Important data fields are for example:

• • Image title
  • Copyright notice
  • Image description (caption)
  • Keywords
  • Place (country, state, city)
  • Contact details
  • Urgency [scale from 0 (high) to 8 (low)]

XMP – Extensible Metadata Platform

XMP is the main data format for storing documentary metadata in image files. It was developed by Adobe and first released in 2001. Since modern image formats such as WebP rely on XMP and no longer offer IPTC-IIM support, XMP should be the first choice today. The format is flexible and satisfies even those who want to use time-honored data fields and structures, because both IPTC schemes (IPTC Core and IPTC Extension) and also the Dublin Core scheme can be stored via the XMP format.

What are the benefits of metadata in image management?

The most important point is obvious. Metadata can be indexed for quick retrieval of files. This applies in particular to metadata in text form, e.g. keywords (tags) or image descriptions (captions). By assigning unique image numbers and consistently indicating the author, retrievability can be further increased. But technical metadata such as image format, pixel dimensions, date taken or geocoordinates can also serve as search parameters. They often form the data basis for intelligent search filters.

Metadata in the stock photo industry

In digital image archives (scientific as well as commercial), among professional photographers or within the stock photo industry, photometrics have been recognized as indispensable for many years. In the meantime, they have also become much more important in marketing and PR as well as in online retailing. Metadata is needed to help marketing teams and distributors get fresh imagery easily and quickly. Product photos, for example, can be keyworded with unique product codes or manufacturer numbers; characteristics such as size, color or price can be additionally stored – and if certain people are pictured more frequently, it makes sense to “tag” them accordingly. Even subjective content such as moods, concepts or image interpretations can be documented by using appropriate keywords. However, the vocabulary should be controlled here, i.e. you should specify in advance exactly which terms are to be used in which spelling for keywording.

Metadata for managing licenses and image rights

Let’s move on to another important point. Even the management of image licenses, copyrights or declarations of consent can only be realized by storing metadata on the image itself or within an image database. Without metadata, professional license management is simply not possible.

Conclusion

Of course, the management of photometadata requires professional software solutions. For single users such as self-employed photographers, a local database within programs such as ACDsee or Adobe Lightroom may suffice here. However, if many different stakeholders in a corporate environment are to access the same image stock at the same time, it is necessary that all information is kept securely available in a central solution. In other words, it’s hard to avoid a cloud-based software.

Test the image management software of teamnext

teamnext’s Media Hub is a cloud-based solution for marketing and PR teams of all sizes. Metadata contained in image files is automatically imported, merged and indexed here and can of course also be edited in a variety of ways. Tools such as batch processing (mass indexing and renaming), rights management or AI-based recognition of persons and objects leave nothing to be desired in metadata management.
If we have made you curious and you simply want to try out the possibilities of a professional image management software, then you can start immediately with our free 14-day test phase for the teamnext | Media Hub with integrated AI platform. In addition, you can book an appointment for a free online product demo with one of our experts at any time. Simply use our contact form for this purpose.