Some people eat, sleep and chew gum, I do genealogy and write...

Saturday, September 19, 2015

Preserving Your Digital Files

"Graphics file formats (EN version)" by Konrad170This vector image was created with Inkscape. - Own work. Licensed under GFDL via Wikimedia Commons -
When I write about preserving your digital files, I am referring to a number of different levels of preservation. A digital file is a complex series of electronic impulses stored on some type of media. For example, if I use a "digital" camera to take a photograph, the light rays entering the camera through the lens are directed to a sensor that converts the light waves into electronic impulses. For a more detailed explanation, see What is a CCD? The electronic impulses are recorded by the computer in the camera and "developed" or changed into a type of file that can be read and stored by a computer, usually a JPEG file or a RAW file. Once the file is in a readable file format, it can be transferred either by a USB or other wire connector or by WiFi (depending on the camera) to my computer. In fact, there are many different file formats: TIFF, PNG, GIF, JPG, JPG 2000, RAW, BMP, PSD, PSP, PPM, PGM, PBM, PNM, WEBP, just to name a few more. See Wikipedia: Image file formats.

The camera itself may have a way of storing photos and the "original" of the photo will remain in the camera's storage (either internally or on a memory card inserted into a slot in the camera body) until it is erased or some destructive act occurs that erases the camera's memory.

Now an exact copy of the original file (the electronic impulses forming the image) from your camera now reside on the memory of your computer. All electronic devices rely on electricity to function. The copied file resides in your computers permanent memory, usually on an internal hard disk drive or in some newer computers, an internal flash drive.

This example has so far been restricted to image files. There are many, many more file formats out there in the computer world. Almost every program has its own file format, usually designated by a three or four letter file extension. There are hundreds of file formats listed online. Here is a sample some of the websites contain file format lists:

As an example of the complications involved in file formats, the image at the beginning of this post was originally saved as an .svg file. That is what as known as a type of "vector" file. In order to use the file as an illustration in this blog post, the file had to be converted to a .jpg or .jpeg file type. The easiest way for me to do this file format change was to do a screenshot of the original file format. I opened the file in Adobe Illustrator and then did a screenshot. I could also have saved the file in .pdf file format and then used Adobe Acrobat Pro to change the file format to another image format such as .jpeg. This particular file is protected by the attribution in the caption. Here is the substance of the attribution license:

OK, so at this level, I have the following concerns:

  • The file format of the image stored in my camera
  • The file format used to transfer the image from the camera to my computer
  • The format I use to store the format and use it 
  • The copyright implications of the image
  • Any possible use by others of the image
Now we come to the issue of loss. What could happen to this original image sitting on my computer?
  • The image could be erased by accident or intention
  • The image could be stored in a format that could not be opened by any program I own or have access to
  • The image could be altered and the original unsaved
  • My computer system could become obsolete and the image lost
  • My entire computer could be lost by theft, natural disaster or other occurrence
Obviously, this list could go on. 

If you have images, genealogical data files, documents etc. on your computer, then those files probably have a variety of file formats. Over time, these formats may change or be abandoned. The effect will be that the files will become more and more difficult to open or may not be able to be opened at all. The process of maintaining those digital files is called data migration. 

In short, any file type on your computer is subject to ultimate loss over time. Either through technological advance or through the natural consequences of change over time, file formats become obsolete. Backing up you files is a really good idea. It is also a really good idea to have a backup system that includes making a complete copy of your files in a physical location other than your own house or dwelling place. I had a discussion recently about someone who was worried about having multiple copies of her files on different hard drives. That is not a problem, it is called backing up your files. But even careful backup is not enough.

You need to be well aware of file obsolescence. Take the time to examine your older files and move them from older storage media to newer media. The classic example is the having data stored on 3.5 inch floppy disks (or older) and now trying to recover the files. You may very well be able to recover the files, but may not have any program that will open the recovered files. Periodically move you files to newer programs. You may find that the older files, even within the same program, are now unreadable by the newest versions of the file. 

Here is another example to conclude this post. What if you used a very popular program called Aldus Pagemaker and created a history of your family. Now you want to use that file today. How would you go about opening the Pagemaker file? Are you aware of a program that will read Pagemaker files? How long will the programs that can read Pagemaker files be available?

Think about it. 

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