What Can EXIF Data Include?

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.

What is EXIF data?

The “Exchangeable image file” format (Exif) is a specification for the image file format used by digital cameras with the addition of specific metadata tags. The meta data are written by the camera and can be post-processed using certain desktop applications. Coppermine is capable of displaying some of the EXIF data within the pic info section, like date and time information, camera settings, location information, descriptions and copyright information.

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.

What information can be found in EXIF data?

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

Examples of EXIF data

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.

Dimensions	4000×2667
Width	4000 pixels
Height	2667 pixels
Horizontal resolution	300 dpi
Vertical resolution	300 dpi
Camera manufacturer	Canon
Camera model	Canon EO S7000
Exposure time	2 seconds

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).

Viewing EXIF data

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.

Free EXIF tools

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

Viewing EXIF data using an internet browser

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.

EXIF by right-clicking

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.

EXIF and data security

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.

EXIF and loss of data

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.

Different Flavors

Please note that EXIF is far from being a standard: each camera vendor uses his own “flavor” of EXIF – therefore, the EXIF meta data will differ from camera to camera. Coppermine tries to circumvent this by using different libraries for the most common camera brands and only displaying the exif data that are most common for all brands.

Exif data from the following Camera brands are currently supported:

Canon
Fuji
Nikon
Olympus
Panasonic
Sanyo

The exif libraries reside in the folder http://yoursite.tld/your_coppermine_folder/include/makers/, but usually those files should be left alone and don’t need editing.

How it works

It would be very time-consuming if an application would process an image each time it gets displayed to extract the exif data embedded into the image. That’s why Coppermine populates a separate exif database table only once per image, during the upload stage of the image when that image get’s resized as well (using the exif data embedded into the image). That exif data is being written into the table that works as a sort of cache. Each time the image get’s accessed (i.e. when it get’s displayed embedded into Coppermine) the exif data stored in the database is being read to populate the exif meta data. This is much faster and less ressources-consuming. The processing of exif data is only being performed if the corresponding config option “Read EXIF data from JPEG files” is enabled.

EXIF manager

Coppermine comes with an EXIF manager that let’s the coppermine admin decide what EXIF data should be displayed within coppermine. Please note: if the exif data doesn’t exist within a particular image, coppermine will of course not be able to display them. Coppermine is not an editor for exif data – it just displays the exif data that exists in your pics.
To access the exif manager, go to coppermine’s config and click within the section File settings at “Manage exif display” next to the line “Read EXIF data in JPEG files” or choose the corresponding admin menu entry.

Tick the checkboxes in the exif manager that you want to show up in coppermine’s pic info section (if the image file actually holds this particular set of information). Remember though that there is no guarantee that a particular field will be populated or displayed – as explained above, each camera vendor supplies a set of supported exif fields that differ from other vendors.

The following exif parameters are currently supported: