Digital Image degradation over time. (1 Viewer)

[Tom Lawson]

During the current lockdown I have been going over some of my past birding trips and digitising some of the slides.The quality of the images is very variable,from excellent to unusable,and very much depends on the film that I used,although all the slides have been stored in archival folders.Does anybody have any idea of the length of life of digital images.Some of my digital images are now 15 years old,but seem as good as the day I took them.Do digital images deteriorate with time?
Tom Lawson.

 

[Essex Tern]

As long as you have a safe method of storage, and the image file has not corrupted in any way - there will be no degradation over time - the image is a set of characters stored in a datafile, so they will remain the same for life.

As software developments arise, you may be able to process an image better, so the image quality could even improve with further processing of a raw file for example.

 

[opisska]

Really depends on what you store the digital images on - that's the thing to degrade, not the image itself, that's just an abstract concept. Sadly, a lot of storage methods are sort of "all or nothing" - it works, until it doesn't and then you simply lost the images altogether. Degradation in the form of the image still being a working file, but "looking worse" is quite unlikely. In any case, if you want to keep your digital files (not only images) for a long time, there is no "store and forget" way to do it - to put it simply, digital data does not exist long enough for us to have a reliable long-term storage, because not enough time has yet passed to test it. CDs and DVDs last years, possible decades, but they all can suffer from degradation of plastic materials with time. The most reliable storage is probably a magnetic HDD (or even better an array of those), but one that is connected to a computer and accessed regularly, so that if it starts to fail, you can notice that and copy the data - an external HDD, unplugged and in the drawer is pretty much "Schrodinger's data" - it may be there or not. Any Flash/SSD is much worse as unplugged storage, as the charge WILL be gone at some moment in the future - nothing has infinite resistivity. Overall, the best way to keep your data is to keep it with two different methods and copy it to a new device once in a while.

 

[Mono]

As above digital images won't degrade. The storage media may fail so it is important that you hold back ups. The ultra recommendation is four copies; one on a physical device you hold, one on an offsite physical device (swap with a friend), and two cloud backups with different providers.

There is also a question of what you are storing them for. When you shuffle off this mortal coil will someone just press delete?

 

[marcsantacurz]

As has been pointed out, storage media can degrade and have bit errors.

Diglloyd.com has an article about this. He also offers a product called "integrity checker" or something like that, which can periodically verify that images have not changed and the data is correct.

https://diglloyd.com/blog/2019/20191218_1620-backup-and-data-integrity.html

Personally, I have my most recent files on my laptop, and they are replicated to a RAID5 NAS drive I have at home. The NAS drive then backs itself up to Dropbox. So, I keep between 2 or 3 copies of files, depending on if the file is still on my laptop or if I've archived it off to the NAS only. Lightroom works pretty well having some folders on a local drive and some folders on a network drive.

Marc

 

[opisska]

As has been pointed out, storage media can degrade and have bit errors.

Diglloyd.com has an article about this. He also offers a product called "integrity checker" or something like that, which can periodically verify that images have not changed and the data is correct.

https://diglloyd.com/blog/2019/20191218_1620-backup-and-data-integrity.html

Personally, I have my most recent files on my laptop, and they are replicated to a RAID5 NAS drive I have at home. The NAS drive then backs itself up to Dropbox. So, I keep between 2 or 3 copies of files, depending on if the file is still on my laptop or if I've archived it off to the NAS only. Lightroom works pretty well having some folders on a local drive and some folders on a network drive.

Marc

HDDs shouldn't exhibit bit errors, because of control cheksums. You still can get larger corruptions, but then such a software presumably only tells you it's corrupted (as it's not feasible to correct a whole sector from some checksum).

This also reminds me of another risk: software going haywire. We had a problem where Google Picasa would randomly corrupt images on disk. This is particularly nasty because if you do regular backups, then this will get copied to them as "new changes" - only "once for all" backups are safe against that, but that's difficult to manage long term when your data comes in gradually.