Technology obsolescence is generally regarded as the greatest technical threat to ensuring continued access to digital material; the information on a computer disk cannot be read or understood unless there is also the right computer, disk drive, operating system and software to use it. This would have the following implications -

a. the actual computer technology used to create the digital images changes quickly which means that a CDROM disk could last over a hundred years but there may no longer be a computer or suitable ROM drive to read it

b. a wide variety of software programs that change frequently and where newer versions may have limited backward compatibility. Timeframes during which action needs to be taken is measured in only a few years, perhaps only 2-5, as opposed to decades for traditional materials

c. software programs that compress images to make files easier and more compact to store may in time be rewritten and may not open old files

d. magnetic storage products such as hard drives, floppy disks and tapes are the least stable storage option and may degrade more quickly overtime resulting in poor quality or lost data

e. widely differing types and quality of manufactured disks

f. inappropriate storage conditions and poor handling and management techniques leading to damage and deterioration of files.

g .issues raised by digital technology are relatively new and there are no studies that clearly define the life of CDs and other optical products. Manufacturers of writable CDs have undertaken Accelerated Life tests on their products and national museums and archives are now actively establishing standards and methods of preservation for digital media, but until further information is available, there are a few simple recommendations that should be followed.

Scanned images should be saved where possible in uncompressed format (BITMAP or TIFF). These are significantly larger files for storing, but do not compromise the original quality of the stored image.

Digitally created images are most usually stored in compressed format (such as JPEG or GIF). These are significantly smaller files for storing but may compromise the quality of the saved image. Note – compressed files are created using software programs that may overtime be rewritten and access may be lost if saved data is not updated with a later software version.

Use the highest quality / resolution scanner that is available to you to optimise the images being saved. Note – resolution is measured in pixels (dots) of red, green and blue values. The higher number of pixels per inch (ppi or dpi) will allow for better quality scanned images.

Make more than one copy of the CDs and store in different places. Since CDs deteriorate with handling and exposure to light, dust and heat it is advisable to keep a master copy for reference and a backup copy for access and viewing. Note – copies used for handling and access will have considerably shorter lives and may need to be replaced far sooner.

Document image details as fully as possible - a) PC, Scanner or Camera specifications and CD Writer Drive details (speed, manufacturer, serial numbers / date of purchase) b) Title and Version of the software programs used to create, scan, edit or save your images (including the compatible operating system in use, eg Windows 98) b) CD size, speed, type and manufacturer c) Content of the CD – index and name the images for ease of recognition and access d) The source of the image – digitally produced or scanned image, photo print or paper clipping (denotes the original quality of the image) e) File format (eg. Bitmap, JPEG) and size of files stored f) Date of original digital archiving.

Do not stick labels on CDs (or try to remove them if already applied). Denting, bending or scratching the media can cause physical damage and loss of the stored data (See Choosing Your Media). Do not write on your CDs with a pen or hard point. Using permanent markers may also allow chemical seepage from the ink into the recording layer and cause deterioration of the stored files.

Do not delay in updating both hardware and software technology as they become available. Refresh the data from the old medium to the new whilst an element of backward compatibility is still available.

Remember to refresh and update all copies of your CDs if you have spare or master copies in a different location.

Record all new details for updated images with revised hardware or software specifications, dates and file details.

Handle your CDs as little as possible. Store them in a recommended archival standard storage system and optimal environment.

Do not neglect your original non-digital images. Store your photos and clippings in archival standard storage systems with minimal handling. If your images are digital in origin, it may be worth taking the most special files ‘out of the digital environment’ and having a printed version made as well. (It may seem like going backwards, but two types of storage medium are usually better than one!) Remember to store these images in the optimal environment for photographic prints to extend their lifespan.