Metadata is simply information attached to your image file that is not the image itself. It the term is confusing, you can skip the “meta” and just think of it as data. The reason it’s called metadata is that a digital image itself is made up of data (even though we don’t normally think of a picture as data). So data about that data gets the prefix “meta”. Simple, right?
Enjoy the photos, which are sampling of faves from the recent trip through the western U.S. They are copyrighted and not available for free download. Please click on the images to go to the gallery page, or contact me with any specific requests. Thanks for your interest!
Speaking of simple, this is a two-part post meant to cover the basics of metadata. It is probably worth learning about all the different types of metadata, all the different ways it can be put to use. But I’m going to concentrate on what I think is most important about metadata, including, in the 2nd part, why it’s important to your photography. Tune into that one, since it discusses what most other books & blogs seem to skip. But first things first.
Metadata gets entered into fields, like with a digital database. This set of data gets attached to each image file. Using the database analogy, each image file is essentially a record, a line in your database.
Most common image formats are compatible with the main metadata formats. So whether you shoot in RAW or Jpeg the metadata is treated similarly. And when you convert to TIFF, PSD, etc., your metadata remains compatible with the new image format.
When you shoot RAW (which you should be doing if your camera allows it), some metadata is stored with the image file. But much of it goes into a special little file called a sidecar. Sidecar files, with the suffix .xmp, are associated with the image file they belong to. They are created with each image you record, and you’ll see them when you view your folders on disk.
Adobe created a non-proprietary RAW format called DNG, where the metadata is stored along with the image into one file – no sidecar files. I use DNG because I like having both image and metadata in one (slightly smaller) file. Of course I know sidecar files are designed to tag along with their image files wherever they go, but like marriages, when there are two files there is at least a chance they will be separated.
There are two basic types of metadata attached to your photos: Exif and XML (or IPTC extended). There are a couple other schemes, but these are the two most used and useful for the typical photographer:
- EXIF: Exif stands for Exchangeable image file format. This type of metadata is automatically attached to your image at capture. Among other things, it includes image type & size (width/height in pixels), camera & lens used, your settings (aperture, shutter speed, ISO, focal length), date and time of capture, and GPS location (if your camera does that).
Have you ever been glad to see that “date last modified” next to the photo on disk, a reminder for when you last edited? The Exif metadata would say “you’re welcome” if it could talk. The important thing to remember about Exif is that it’s recorded with no action on your part. It’s usually thought of as being non-editable, but you can easily edit time of capture and even the other fields if you’re really motivated and have the know-how.
- XMP (IPTC Extended): Here is where the photographer enters all sorts of information about the image. It is not done automatically at capture, like with Exif. And you can edit all of it later. It includes information like the photographer’s name, address, email, website, etc, along with copyright information. Note that many cameras today enable you to enter your name and copyright straight into the camera; in which case, it’s included with the Exif not the XMP.
XMP also includes important stuff like title & caption, keywords and credits. It includes model name, age & contact info. and whether or not you have a signed model release. And there is more; so many data fields to fill! Fortunately you don’t need to fill out all of them.
Background of XMP: The original format, called IPTC, stands for International Press Telecommunications Council. The word “Press” should give you a clue to the origin and nature of this info. When they were going digital back in the former world, news agencies needed a way to organize and communicate all the relevant details attached to their pictures, stuff that was formerly written in notebooks then placed in manual filing systems.
The extended part is represented by added fields where even more fun stuff is entered. In 2001, Adobe incorporated these extra data fields into an XML-based format and called it XMP (Extensible Metadata Platform). As mentioned above, it is XMP that allows the creation of sidecar files along with the combining of image- and meta-data into one file (DNG). And with XMP, the user can create custom metadata fields.
Think of XMP as a universally-recognized, open-source format. Like pictures in Jpeg format, metadata in XMP format can be sent hither and yon, where a wide variety of software recognizes and displays it.
Handling Metadata – The Basics
Nearly all modern image-editing/organizing software is compatible with Exif & IPTC/XMP metadata formats. Programs like Lightroom, Photoshop, Aperture and GIMP display the fields and let you enter and edit metadata. There are a few free programs along with some older no-longer-supported software that does not accept, save or display standard metadata formats. But most do.
Even better, as mentioned above, you can convert the image to another format (like Jpeg) and send it to someone else. Then, even if that person uses different software, they can display the same metadata. Adobe deserves a tip of the hat for making this cross-compatibility happen; it warn’t always thus!
As you learn to use your image-processing software of choice, you’ll learn where and how to enter the metadata. In Lightroom, one of the panels in the Library Module is labeled Metadata. Here you’ll quickly become familiar with where to type in stuff like keywords, title, caption and other info. And you can enter information that is the same for many images just once. Or, after the fact, you can “synch” the metadata from one image to a bunch of others. It’s really quite easy and intuitive.
In the second part of this post, next Friday Foto Talk, you will learn which metadata is especially important, and how to use metadata to let Google and the other search engines know exactly what your images are all about.
Have a great weekend!