Image archiving strategies of the past were many and varied, but all depended on putting the image itself somewhere for safe keeping. For instance, treasured family photos have often been found in shoeboxes or bags that were stored in someone’s attic for a very long time. More organized folks kept photo albums, and the diligent ones even kept the corresponding negatives safely tucked away somewhere. Serious photographers with thousands of images kept transparencies and negatives organized in hanging files. That was then.

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Now there is no film or paper, and no "image" in the true sense of the word. We generate image files with digital cameras, but these image files are not images. They are invisible bits and bytes that are used to construct the image each time it is viewed. This fact poses significant problems for the long term viability of digital images. The ability to view or print digital image files depends on computer hardware being compatible with the media upon which the files reside. It also depends on viewing software that is compatible with the image file format, the computer, and its operating system. If any of these compatibilities vanish over time, the ability to view or print the digital image file vanishes with it, no matter how safe the digital image file has been kept. In addition to long-term file compatibility issues, archiving strategies need to account for normal events that could jeopardize the files. These include accidental erasure, computer viruses, hard drive or other media failure, and catastrophes like fire and flood. It takes a lot more than a shoe box to pass these files on to future generations, and anyone who shoots with a digital camera will eventually have to figure out how to store the thousands of files generated. Keeping them strewn around on your computer’s hard drive is like keeping film strewn throughout your house. Something is bound to happen, and when it does it won’t be good.

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Currently, the most suitable and common storage media are external or internal hard disk drives, and removable media like CDs and DVDs. A system using these or any other media for image file archiving should ideally meet the following five criteria:

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1. Accessibility. There should be a means to easily find any given image. This issue is easily addressed by a good cataloging program like IMatch, which I can highly recommend. This program will let you categorize and find image files even in huge libraries, regardless of how they are stored. A good level of accessibility can also be had without any cataloging program by simply creating a logical folder structure in which to store your files. This together with a good image browser will let you find files in short order. Attaining a good level of safety for your stored images is more difficult.

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2. Safety. The data should be safe in the face of hard drive failures, computer viruses, accidental erasures, and even catastrophes like fire. Hard drive storage is convenient and fast, but it is far from safe. Hard drives are quite vulnerable to mechanical failures. These can occur from impact or deterioration of their very precise internal mechanisms over time. This is especially true if the hard drive is stored where temperature and humidity are uncontrolled. No magnetic storage media is truly archival. Magnetic information can fade over long periods of time, especially if the media is subject to even weak external magnetic fields. Magnetic coatings can also separate from the substrate material that gives them mechanical strength, but this happens most often in magnetic tape. Data on hard drives is also subject to destruction by computer viruses and simple user errors. RAID disk drives can offer on-line redundancy that answers the file safety issue in the event of mechanical hard drive failure. Unfortunately, RAID systems are ineffective in cases of catastrophic events like fire, and they are as vulnerable to computer viruses and human error as any hard drive. RAID systems are also relatively expensive. With any media type, only a good offsite backup or duplicate, that is updated regularly, can prevent data loss in catastrophic situations. Data storage on quality CD and DVD media is archival, and keeping a duplicate copy at an offsite location makes it a very safe alternative. Under reasonable conditions, high quality media of this type will last 100 years or more. But, in far less than 100 years it will be impossible to find hardware and software that are compatible with CD or DVD, much less with today's RAW file formats. In addition, CD and DVD media was never fast or convenient.

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3. Convenience. Ideally, the system should be convenient to use on a day to day basis. Hard drives offer excellent convenience because they are fast, can store loads of data, several can be connected to a computer at once, and all of your image files can be online continuously. CDs and DVDs store relatively small amounts of data, they are slow, and only one at a time can be accessed by a computer.

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4. Ease of converting file formats. Digital RAW files generated by today’s cameras are doomed to obsolescence in the fairly near future. If they are to be useful in the future they will eventually need to be converted to a standard format, if one is ever agreed upon. At the very least, they will need to be converted to something that is compatible with media, software, and computers, of the future. Image files on a hard drive are converted most easily. A program reads files from one folder and outputs the converted files to another. It doesn’t get much easier than that. If there are many, converting files kept on CD and DVD is a huge and time consuming chore. Each one must be manually loaded and then read by a conversion program. The converted files must be written somewhere and eventually copied back to the output media. In any circumstance, file conversion probably means cataloging everything that is converted from scratch. Cataloging the converted files is a big problem, though under some circumstances, with some software, it can be avoided.

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5. Ease of transfer to future media. No media type will be around forever. It is a pretty good bet that fifty years from now it will be either difficult or impossible to read today’s Compact Disk media. Again, data stored on a hard drive is most easily transferred to other media. It is all online, accessible, and ready to be copied to whatever the new device happens to be.

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We used to archive our image files on CD and DVD media, keeping duplicate copies of each CD and DVD at an offsite location in case disaster strikes. We started using this method years ago with film scans, and simply kept doing it when we moved to digital cameras. It seemed like a good idea back when TIFFs were king and hard drives were smaller and more expensive. Today it is simply not worth the fuss. Though it worked well enough, the problem of file format and media obsolescence loomed ever larger as we burned more DVDs. Finally, we made the switch to archiving images to a pair of large hard drives, one of which is stored offsite. These hard drives are huge, fast, and the probability of the main disk and its off site duplicate both developing problems at the same time is incredibly remote. Since the duplicate is offsite and only occasionally connected to a computer for updates, it is reasonably safe from virus attacks and accidental erasure. Just to make sure, we added a third hard drive to the mix, which is also kept offsite. The offsite backups are updated alternately so all of the data is never connected to the computer at the same time. This scheme virtually eliminates the chance that all of our files would be lost in any catastrophe. This archiving method does not address the fact that magnetic media is not archival. Instead it relies on the media being replaced because it has become obsolete before time can take a significant toll on the magnetic properties of the media. Having the discipline to update the offsite duplicate disks on a relatively frequent and regular basis is the weak link in this system. Using a redundant flavor of RAID for the main disk better assures the safety of data generated between updates of the offsite backup disk, but a little diligence with local backups can still provide a very good level of safety.

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The only certainty in this digital age is rapid change. If someone finds a box of CDs or an external hard drive in your attic a century from now the media and the files on it will both be useless. It is quite obvious that the digital image files of today will not survive far into the future without periodic maintenance. Who is going to maintain your image files ten, twenty, or fifty years after you are gone? It is sad but true that many, if not most, digital images from today will be lost to the obsolescence of their file formats or media type. Our great grandparents could pass wonderful black and white images down through generations with nothing more sophisticated than a shoe box. Without maintenance of any kind, many of these images survive intact. Perhaps some digital genius can learn from this and come up with an electronic equivalent of that shoebox. Without that, the best way to ensure the long term survival of an image is to print it using high quality archival materials. It can then be put into a shoebox (preferably one that is acid-free) where it will likely survive for a couple centuries. Without any maintenance, such a print will far outlast the file from which it was created.

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Happy archiving.

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Notes:

As of September 3, 2007, 750 GB SATA hard drives are available for less than $200 each. Smaller sizes like 500GB are considerably less. These offer a vast amount of storage, so there is no good excuse for not backing up your images.