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What is Metadata?

Understand Metadata: The Hidden Information in Photo Files

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Metadata viewed in Photoshop

Photoshop allows you to view a great deal of image metadata by going to File > File Info.

© S. Chastain

Question: What is Metadata?

About EXIF, IPTC and XMP Metadata Used in Graphics Software

Answer: Metadata is a term for the descriptive information embedded inside an image or other type of file. Metadata is becoming increasingly important in this age of digital photos where users are looking for a way to store information with their pictures that is portable and stays with the file, both now and into the future.

One type of metadata is the extra information which almost all digital cameras store with your pictures. The metadata captured by your camera is called EXIF data, which stands for Exchangeable Image File Format. Most digital photo software can display EXIF information to the user, but it is usually not editable.

However, there are other types of metadata that allow users to add their own descriptive information within a digital photo or image file. This metadata might include the characteristics of the photo, copyright information, a caption, credits, keywords, creation date and location, source information, or special instructions. Two of the most commonly used metadata formats for image files are IPTC and XMP.

  • IPTC is the standard developed in the 1970's by the International Press Telecommunications Council. It was initially developed as a standard for exchanging information between news organizations and has evolved over time. Around 1994, Adobe Photoshop's "File Info" form enabled users to insert and edit IPTC metadata in digital image files and so it was adopted by stock photo agencies, and other publishing businesses outside of the news media.

     

  • XMP is the new XML-based "Extensible Metadata Platform" developed by Adobe in 2001. Adobe worked with the IPTC to incorporate the old "IPTC headers" into the new XMP framework and in 2005 the "IPTC Core Schema for XMP" specification was released. XMP is an open-source, public standard, making it easier for developers to adopt the specification in third-party software. XMP metadata can be added to many file types, but for graphic images it is generally stored in JPEG and TIFF files.

Much of today's photo-editing and image management software offers capabilities for embedding and editing metadata in your image files, and there are also many specialized utilities for working with all types of metadata including EXIF, IPTC, and XMP. Some older software does not support metadata, and you risk losing this information if you edit and save your files with embedded metadata in a program that doesn't support it.

Prior to these metadata standards, every image management system had its own proprietary methods for storing image information, which meant that the information was not available outside of the software — if you sent a photo to someone else, the descriptive information did not travel with it. Metadata allows this information to be transported with the file, in a way that can be understood by other software, hardware, and end users. It can even be transferred between file formats.

Photo Sharing and Metadata Fears

Recently, with the rise of photo sharing on social networks like Facebook, there has been some fear and concern about personal information such as location data being embedded in the metadata of photos which are shared online. These fears are generally unfounded, however, since all the major social networks strip out most metadata including location information or GPS coordinates.

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