Categories of Photo Date Metadata
A single digital photo will have a date in several different metadata date fields. The different date metadata fields are grouped into categories. The two categories of photo date metadata discussed in this article are:
- Exif (stands for Exchangeable Image File Format)
- File Properties (also know as System)
Exif Date Metadata
When a photo is taken with a digital camera, the date and time the shutter was pressed is recorded in a field in the Exif metadata category. That Exif date field is called DateTimeOriginal, and is a digital photo’s most important date.
Typically, a camera will also add the same date to Exif fields called CreateDate and ModifyDate.
It’s not just dates that are added to Exif metadata fields. Exif metadata includes details such as the camera make and model, camera settings, and much more.
Watch Out for Exif Date Problems
An important task for professional photo organizers is to examine the Exif date metadata of clients’ photos for signs that dates are incorrect. Exif dates can be wrong for several reasons including:
- The camera date was not adjusted when the camera was used in a different time zone.
- The camera date automatically reset to the factory default when the battery was removed for recharging. That is a common problem for photos taken with an early digital camera.
File Properties Date Metadata
File Properties metadata is also known as System metadata.
Details about a digital photo—the pixels and Exif metadata–are stored in a package called a file. When a picture is taken with a digital camera, both a photo and a file are created. The date and time the file was created is recorded in a File Properties field called Date Created (or Created Date).
While the file’s Date Created and photo’s Exif DateTimeOriginal date will be the same at first, the file’s Date Created can change. For example, when a picture I take with my phone is uploaded to my computer, the file’s Date Created is changed to match when the file was created on my computer.
When a file is exported (from an Apple Photos Library, for example) the exported file will have a Date Created matching the date it was exported. The same thing happens when a file is downloaded from cloud storage. Converting a photo to another file format will also change the Date Created.
File Properties Metadata is not always labeled as such. Some software labels fields such as Date Created without any indication that the date is a File Properties or System date, and not an Exif date.
Watch Out for Photo Date Problems
It is vital that professional photo organizers understand the photo dates they view. Many applications display a file’s Date Created, but no Exif metadata dates. Finder for Mac is a good example.
While the file’s Date Created displayed may be the same as the photo’s Exif DateTimeOriginal, you should never assume it is.
Many applications used by professional photo organizers have a Capture Date field. The intended purpose of the Capture Date field is to display the date the photo was taken (captured), and it usually does. However, if a photo has no Exif date metadata or insufficient Exif date metadata, the file’s Date Created may be displayed in the Capture Date field.
STUFF To Conclude With
If you are a professional photo organizer, you cannot be sure you are delivering correctly-dated photos to your clients if you do not understand photo date metadata. It’s essential to be able to view Exif dates, and to identify photos with incorrect, incomplete, or missing Exif dates.
This articles is intended as a basic introduction to photo date metadata. I have attempted to use accurate terminology, but unfortunately, photo and photo metadata terminology varies by application.
For this basic-level article, it was necessary to use incomplete explanations for complex topics.
The Exif field names used in this article are those used by Exiftool. I chose to use those terms because they seem to be used most often in photo software used by professional photo organizers.
A list of official Exif field names can be found on the JEITA website.