Tagging your images is so cool, compared with using plain old folders…at least that’s what everyone says But how do your carefully created keywords get attached to your images? What are EXIF, IPTC and XMP? And most of all…why should you care about all of these acronyms? Understanding the different types of image metadata will help you better manage your pictures.

Why is image metadata cool?

Metadata in general is defined as “data about data”. In particular, image metadata is information about a specific picture. There are two types of image metadata: technical information about the image and information about the contents of the image. I usually refer to these two types as: technical information and content information. Technical information contains things like: camera type, ISO speed and apperture value. This type of information is created by your camera each time you take a picture. Content information, on the other hand, contains things like: subject, country, category and keywords. Content data is created by you, the photographer, since you’re the only one who can provide content data.

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The easiest way to distinguish between different types of image metadata is to think about who needs to create each type. Technical information about an image (EXIF) is created by the camera, while content information (IPTC/XMP) is created by you, the photographer.

What about all these names like: EXIF, IPTC, XMP?

All of these names represent standards for saving technical and content information about images. They are essentially standards for data portions that can be added to image files. While EXIF and IPTC have been designed specifically for image file types (.jpg, .gif, .tiff), XMP data can be embedded in multiple document formats including PDF. Because XMP (developed by Adobe) is newer, it has been developed as a superset (that means that it contains) of IPTC core elements. This means that software usually can save content information in both formats.

Here is an easy way to remember how these names are being used: EXIF is the standard for representing technical information about an image while IPTC and XMP are standards for representing content information about an image.

EXIF contains technical characteristics of the picture

EXIF contains information generated by your digital camera each time you take a picture. It contains technical information about the picture itself like:

• ISO speed
• Apperture value
• Exposure
• If the flash fired or not

As you can see, this type of information is generated by your camera and represents all the technical characteristics of your picture. However, it does not contain any information about the contents of your picture. Also, another characteristics of EXIF data is that you are not supposed to modify it. There is software that will allow you to modify EXIF data, but this data is not intended to be modified. It doesn’t really make sense to change it anyway since it is generated by your camera.

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Tagged as: EXIF, IPTC, Metadata, XMP