What is EXIF Data?

For normal picture editing and archiving, details such as res­ol­u­tion, file format, pixel size, and colour data are usually enough. However, if you need concrete in­form­a­tion about the pictures for research, if you do not want to share all metadata due to privacy concerns or if you would like to organise your pictures by date, exposure or camera model, then you should become familiar with EXIF data. This in­form­a­tion contains virtually everything you need to know about the camera, the shot para­met­ers, and sometimes even the location where a picture was taken.

Before digital pho­to­graphy, well-known pro­fes­sion­al pho­to­graph­ers would record details about their pictures by hand in order to avoid making mistakes when shooting or defining suitable para­met­ers. Today, hand­writ­ten notes are no longer necessary since cameras and smart­phones usually save pictures in JPEG format, and auto­mat­ic­ally add EXIF metadata.

EXIF stands for “Ex­change­able Image File Format.” The tech­no­logy behind it was developed in 1995 by the Japanese Elec­tron­ic In­dus­tries De­vel­op­ment As­so­ci­ation (JEIDA) as a standard format for JPEG and TIFF. The EXIF data block contains in­form­a­tion about the technical image char­ac­ter­ist­ics and precedes the image data in a header. Version 2.3 of the EXIF standard has been available since 2010.

The EXIF block contains all details about the technical spe­cific­a­tions and shot para­met­ers of saved pictures. As such, it differs from the IPTC metadata standard which does not auto­mat­ic­ally save extensive in­form­a­tion and only contains content-related image details.

The following image data can be found in an EXIF block:

• Res­ol­u­tion
• File type
• F-number/exposure time/ISO
• Image rotation
• Date/time
• White balance
• Thumbnail
• Focal distance
• Flash
• Lens
• File type
• Camera type
• Software used
• Time of shot and possible GPS tags

EXIF is displayed in the form of tags. Tags are composed of one parameter (e.g. focal distance or bright­ness) and the precise value for the relevant image.

Currently, it is possible to save and store more than 100 technical pieces of in­form­a­tion to one image using the EXIF standard. How detailed the EXIF in­form­a­tion is depends on the camera or smart­phone being used, among other things. Modern devices contain GPS receivers, which means they can save geotags (i.e. geo­graph­ic­al in­form­a­tion about where a shot was taken).

EXIF data can be viewed using most image viewing and editing programs. The only important aspect is that the image must have been saved in a JPEG or TIFF format. Raw image files (i.e. pictures which have not been com­pressed) do not support the EXIF standard.

There are several pos­sib­il­it­ies for viewing metadata, including free tools spe­cific­ally developed for metadata, ordinary internet browsers or pre-installed photo programs.

There is a large choice of free ap­plic­a­tions for fully viewing and editing EXIF metadata. Sub­sequent changes to EXIF data may be necessary, for example, if pictures have to be organised in an archive according to date but the date and time details have not been saved correctly (e.g. due to a change of time zone while traveling or incorrect computer settings).

Another reason why you may need to consult EXIF data is for copyright purposes. EXIF data is important for ad­vert­ising and design companies as well as for pho­to­graph­ers. A pho­to­graph­er may wish to include their in­form­a­tion for licensing reasons or may even wish to hide the details of an image to avoid making their tech­niques and methods public. Companies may want to determine who the owner of a licensed image is if no details can be found.

The following tools are available for download free of charge for fully viewing and editing metadata:

• ExifPro
• Ana­lo­gExif
• ExifTool
• ExifPilot
• Exifer
• Exi­fView­er

EXIF data can easily be viewed using the internet browsers Google Chrome and Firefox. You will only need to download the free Exi­fView­er add-on. Simply search for the extension in the browser menu under the heading “add-on.”

After in­stalling the extension, the EXIF metadata of web images can be viewed by clicking on them and opening the image details with a right-click. However, not all online images will contain EXIF data.

The quickest way to view EXIF data is by right-clicking on the image itself. However, you will only be able to view the most basic metadata (e.g. date, time, file type, and file name). In order to obtain full details, you will def­in­itely need a photo tool or a special EXIF program.

Very few people are aware of just how much in­form­a­tion a photo on our cell phones or a camera can reveal about us. If these images are shared on social media or across other portals, certain un­desir­able details may be revealed in the metadata. Data security is both an important topic and a problem in relation to EXIF data.

For example, up until 2016, as much metadata as possible was removed from images after they were uploaded to Facebook in Germany to keep ex­ecut­able malware that could be contained in the metadata from in­filt­rat­ing user devices and also to protect private data.

However, as of 2016, a court judgment has ruled that Facebook is required to leave the metadata contained in users’ photos unchanged after being uploaded in order to allow the au­then­ti­city of images to be de­term­ined. Since most smart­phones and digital cameras are equipped with GPS functions and some images include a geotag (a location tag) and IP address, users should consider whether they wish to publish their personal metadata on the World Wide Web.

Users who prefer not to share these details should use one of the EXIF tools to erase image in­form­a­tion.

Another potential problem is the loss of metadata after a JPEG image has been edited and saved using an image editing program. EXIF data might not be retained in this case but instead might be deleted by automatic data com­pres­sion. This can be very frus­trat­ing if, for example, pictures need to be organized by date, camera model or certain shot para­met­ers.

If you would like to save EXIF data, you should always be sure to save images in JPEG or TIFF format. When using Adobe Photoshop, for example, you have to use the “Save as” function since the file will otherwise be saved without EXIF data. You should also be careful when using the “Save for Web and Devices” function since EXIF data will be lost in this case too. Always use the “Save as” function whenever possible.