Are Raw Image File Formats Archival?
In the old days, many folks kept their photographs in an old shoebox. Inevitably, they'd get damaged, somehow. So now that you're shooting digital, how do you keep your photographs? Are raw file formats archival?
A raw image file represents the data as captured by your camera. Conceptually speaking, raw files are analogous to the film negatives of old. They aren't really quite images in their own right, but they constitute the source material from which images are produced. In the past, this process of transformation occurred in the photochemical darkroom. Today the equivalent process takes place in the digital darkroom.
In the past, photographers wishing to preserve their images with a maximum of fidelity were advised to safeguard their camera negatives or slide originals. Today that same line of reasoning dictates that photographers should back up their digital negative raw files. Prints or copies made from either film or digital originals invariably contain the limitations both of current technology as well as our own limitations as users of that technology. It doesn't matter whether that technology consists of chemical developers and washes or computers and software programs. The reasoning seems valid in both cases.
But there's a problem in both cases: technology changes over time. In the early days of film, photographic processes such as daguerreotype, cyanotype and tintype represented the state of the art. Even setting all that aside as ancient history, the more recent E-6 and C-41 film processing methods had their competitors. Promising film processes such as Kodachrome K-14 ruled for a time and then faded from the scene. If you still have any unprocessed Kodachrome, getting it developed will be at least as challenging as the earlier cyanotype and tintype. The same thing is happening all over again in the age of digital photography. Support for earlier raw formats is disappearing even as new variants get introduced with most every new camera model released.
As I say, there's a problem. You can only develop your original negative — film or digital — so long as you have access to the needed technology. This is a problem that is likely to get worse before it gets better. It is a problem caused by two underlying factors. First, there's the steady advance of technology that I've already alluded to. Digital photography is still in its youth. New cameras have new capabilities, and new ways of representing even existing capabilities continue to be invented. Each new advance brings with it new challenges that stretch the abilities of existing raw formats. Whether it is the addition of new data sets inside a format with no official place to put such information, or the shift from 12-bit to 14-bit raw recording, the formats of today are constantly being stretched and extended to keep up with the quest for improved images. But beyond that, another factor is also at work. Camera makers are reluctant to share the proprietary technology with other companies since it represents a competitive advantage they feel a need to guard closely.
A few years back, Juergen Specht and a number of online collaborators started an organization called OpenRAW to consider such matters and to argue for an open, documented raw standard. I published an article here linking to a survey they conducted and agreeing with their aims. The fact that I'm writing about this again now can be taken as an indication that the problem is still with us. I don't know that it's gotten much worse, but it hasn't gotten much better either.
Adobe has done a remarkable job adding support for new raw file formats to their Adobe Camera Raw and now Lightroom products. Both can still open even my earliest Nikon D100 images from over a decade ago as well as the newest images from my current Nikon D7100. Open source pioneers including Dave Coffin and others have also done an excellent job of reverse engineering camera maker's ingenious secrets.
But no company or person can keep up with this forever. Sooner or later, we all have to face the prospect that our precious images will be no better off than those old photos in a shoebox. There are several ways to prepare for this possibility, but I admit that none of them are that appealing. Still, each of us should be taking steps to be ready or risk even worse prospects down the road.
The option most often recommended in the early days of digital photography, and still a good one at least for its simplicity, is to save a copy of at least all your best images as lossless TIFF files. The TIFF format has already stood the test of time as one widely supported. At this point, the inertia it has built up should propel it into the future, relatively safe from going out of favor. This does though lock you into whatever your best efforts at raw conversion are today. Once you have converted to TIFF, you've ruled out other, future raw conversion efforts. Yes, you can periodically replace old TIFF file backups with new ones as you learn more and the software itself becomes capable of more, but while you can go from raw to TIFF as many times as you want, there's no going back from TIFF to raw. Think of this solution as being akin to archiving the best print you can make from each of your film negatives.
A more trendy approach, and one that may perhaps fare better, is to archive all your important images using Adobe's DNG image format. This format represents Adobe's efforts at creating portable raw image file format bot for purpose of archiving and in the hopes of convincing camera manufacturers to support it natively in their new cameras. Although this second hope hasn't panned out very well, their first design objective is still quite viable. DNG files provide the ability to embed the original raw file as well so you pretty much end up with the best of both worlds. While you do perhaps limit your options somewhat in the DNG portion of the file, by retain the original raw capture as well you can always go back to it to reconvert with future software. Of course, if you keep both the original raw file plus a DNG without the embedded original, you pretty much have the same thing in two files rather than one. The choice is yours. Adobe has tweaked the DNG format a few times over the years and will likely do so again in the future, but backward compatibility remains high at this point.
A third option is to keep a copy of all your old versions of software so you can use it to read the files you created with it previously. Adobe lets you keep old versions of Photoshop and Camera Raw installed on your computer when you install new ones, so as long as you have the hard drive space, and your underlying operating system still lets you run that old software, this method lets you go back to any of your older images without much effort at all to keep those files readable. Simply never uninstall your old programs, and remember to install everything all over again as you upgrade to new computers. At some point, this will undoubtedly cause far more work than you thought you were getting yourself in for, but in theory, it could work.
That leads me to a fourth option: virtualization. Software exists for both Windows and Mac OS X that allows you to emulate one computer (known as a "guest") inside a program running on another computer (known as a "host"). In addition to DNG conversion, I maintain VMWare images of old, retired computers complete with installed software that I can use to run old versions of programs. You might think that emulating a computer this way would be inherently inefficient, but surprisingly such is not the case. Keep in mind that newer computers are already considerably more powerful than older ones, so any overhead added by virtualization can easily be overcome by the sheer force of speed and power from newer computers. I literally still have installed copies of a dozen different versions of Photoshop plus half a dozen Photoshop Elements versions and more, all of which I can turn to if needed.
As Adobe moves into the cloud, things will get more complicated of course since they can add (or remove) features any time they want. And no one solution will cover every possible eventuality. But by employing one or more of these options you can greatly lessen the chance of being surprised to discover you can no longer open some of your earlier images.
As digital photography continues to mature, camera makers and software vendors will likely grow to accept that their users expect them to cooperate and collaborate more. They will also hopefully understand the importance of providing a broad range of backward compatibility for older cameras and image formats. At this point in time though, users who care about their images would do well to invest in a bit of insurance on their own by adopting some method of backing things up to keep their options open. For now at least, if we want "Open RAW," we should be taking matters into our own hands.