Keeping tabs on your photos can be a real chore. Thankfully, with the right tools, it doesn’t have to be. I’ll be explaining a little about how metadata works and, in later posts, some of the best tools for editing your photo metadata.
Types of Metadata Found in Photos
There are two major standards for saving metadata inside an image file:
Exif, or EXchangeable Image File format, is found in nearly every photo taken by a modern digital camera. The main data it saves includes:
- The date and time when the photo was taken
- Camera settings; the camera model, manufacturer, lens, shutter speed, aperture, and flash information
- A description and copyright
- In some cameras, GPS coordinates of where the photo was taken
XMP, or eXtensible Metadata Platform, is an XML-based standard developed by Adobe. It’s not so common in amateur photography, but it’s becoming more and more common-place. XMP can store all of the same information as Exif, and a lot more:
- Keywords (or ‘tags’)
- Captions, descriptions and titles
- Ratings (1 = poor, 5 = excellent)
- Image adjustments (also known as non-destructive editing, which we’ll expand upon another time)
- IPTC fields (we’ll also be looking further into IPTC later)
Both standards work very well at their job; XMP is obviously more advanced, but whilst Exif is common-place and widely supported, XMP is much more recent and there are few image editors and viewers that support it. For most amateur photography, Exif is sufficient. You can still use keywords (sometimes referred to as ‘tags’ or ‘categories’ to organise your photos in Picasa or Flickr, for example, without touching the Exif information. The information is stored by Picasa, Flickr or their equivalent. There are drawbacks to this method however, which is why XMP is so useful.
Keeping It All Together
The more photos you take (and subsequently the more you have to store), the more important a good cataloguing method becomes. We’ll take Picasa as an example. Picasa is one of the best free pieces of software available: it’s fast, works with the majority of formats and in general does its job very well. As we’ve mentioned, you can add keywords (it calls them ‘tags’) to your photos in Picasa then later search for images using those keywords. The data is stored by Picasa, in its own internal database. So what happens when you decide to change your photo-editing software? You lose those precious keywords that you spent so much time adding, and with it the organisation of your entire catalogue of photos.
A better solution is to keep all of the metadata for each photo stored in the file itself. This way, the metadata always stays with the photo. Send the photo to a friend? Your metadata will still be there. Publish it online? Still there. Change photo editor? Still there, and no need to redo all of your hard work.
This is where XMP excels; it will save almost any data you need to store alongside your photo. XMP can be embedded (store directly inside) many file types, including PDF, JPEG, PNG and Adobe’s standards-based RAW format, DNG. When XMP can be embedded directly in an image file, it resorts to saving the metadata in a separate file, called a ‘sidecar’ file, alongside the main image. For example, if you have a photo with the filename DSC_0001.jpg, the XMP sidecar file would be named DSC_0001.xmp. Using sidecar files looks a bit like a cheat; indeed it’s not the best solution as it means having to remember to always accompany the image file with the sidecar file. But at least your metadata will be portable, and can be read by any program that supports XMP. I’ll be reviewing the best of these programs in a later post.
That concludes the first part in this series on metadata; next up, we’ll be looking into the IPTC standard, geo-tagging and various other ways to keep your photos organised.
Header image credit: Photo pile as mosaic by Quinnanya
