This week, I wanted to take a few minutes to decipher some of the alphabet soup that we lovingly call metadata. Metadata refers to extra bits of information about an image ranging from what shutter speed you took the image at to where did you take the image. To see an image’s metadata in Aperture, select an image and make sure the Inspector on the right is visible (choose Window > Show Inspector if it’s not). By clicking on the Metadata View menu within the Inspector, you can switch between different built-in and custom views showing different metadata fields.
Most images automatically have EXIF (which stands for “Exchangeable Image File Format”) metadata embedded within them. EXIF information is primarily information that the camera knows automatically and can embed into the image for you, such as aperture, iso speed, and focal length. By clicking the EXIF button at the bottom of the metadata inspector, you will see a list of all possible EXIF fields that you can add or remove from a metadata view. As an example of when you’d want to customize a metadata view, if your camera writes GPS information into its images, it’s useful to either add the GPS EXIF fields to an existing view or to make a custom GPS metadata view to quickly see GPS information.
On the other hand, IPTC (short for the “International Press Telecommunications Council” and referring to a set of standards that group defined) metadata is metadata that you, the photographer, know and need to enter about the image. Some IPTC metadata, such as location, will always be the same for a group of images and can easily be entered in bulk. Other fields, like Caption, usually vary per image. Clicking the IPTC button at the bottom of the metadata inspector will let you define what IPTC fields are visible (and to see ones you might not have known existed!).
I’m sure you’ve heard a lot about keywords already, and although keywords are actually part of the IPTC spec, Aperture treats them differently from other IPTC metadata. In addition to the keywords HUD, where you can browse your entire keywords library, clicking the keywords button on the metadata inspector will let you add and remove keywords from an image (there are a variety of other ways discussed elsewhere to manage keywords).
One very cool feature in Aperture is custom metadata fields. Sometimes, you want to add your own fields, like Stock Code, to an image. To do so, select an image, click the Other button in the metadata inspector, and in the two fields with the placeholder values “New Custom Metadata” and “Metadata Value,” type your custom key (”Stock Code”) and value (”ABC123″), respectively. You’ve now defined a custom field that you can search through and inspect.
Aperture also has metadata presets. You might notice yourself typing certain values, such as credit and copyright, over and over. Presets provide a way of saving a set of values so that you can apply the values with two clicks instead of typing in each value. To set a preset up, switch the metadata view to a view with all of the fields you’ll want to save and reuse (I’d recommend using the All IPTC view), type the values you wish to save into the fields, click on the action menu (it has the small gear icon, and you can see the menu in the screenshot) and choose Save as Preset. Enter a unique name. Now, let’s try applying this preset to another image. Select another image, click the action menu, and choose Append with Preset (append will combine the preset with the existing metadata, and replace will overwrite). The values you entered into the previous image are automatically applied to the new image. The other commands in the action menu, such as manage presets, help you organize and work with metadata presets–try playing with the different commands!
The last bit of metadata alphabet soup you’ve probably heard is “XMP.” XMP actually isn’t metadata, but rather it’s a general-purpose container for metadata. EXIF and IPTC metadata are written differently into a file, and custom metadata formats are written in, well, custom ways. XMP provides a generic system for specifying a metadata spec (e.g. the list of fields and information about possible values) and storing values for that spec within a file. Plus, an XMP block can contain multiple metadata groups, such as EXIF, IPTC, and custom metadata. Adobe even uses XMP to store its camera RAW adjustments in addition to EXIF and IPTC information.
XMP can be embedded into an image or written to a separate, sidecar file. Sidecar files are useful with RAW images because you often don’t want to (or can’t) modify a RAW file, and by storing the data in a separate file, you get to leave the RAW file alone while still adding metadata to it. By default, when you export a master in Aperture, you have the option to also export an XMP sidecar file. A donation-ware 3rd party plugin, called Lightbox XMP (which I wrote), gives you the ability to embed XMP or write sidecar files when exporting a version, too. Plus, it has a mode to just write sidecar files for referenced masters so that other applications, such as Adobe Bridge, can gain access to the metadata for your referenced masters, from EXIF to keywords, that you entered in Aperture.
Hopefully this post has given you a better understanding of what metadata is and how to work with it within Aperture!