Do Digital files degrade with time ?

<p>Not sure if it's me or my computer or both, but some photo files that have been saved on my computer seem to have degraded with time. Is this possible ?</p>

<p>Degrade in what way? Everytime you edit a JPEG and resave as a JPEG you will lose a little bit of quality. If you don't edit the file then the file should not degrade unless your hard drive is having problems.</p>

<p>Degraded in what way? Generally speaking, a file is intact, bit for bit, or it's corrupt. There's rarely any middle ground. And data errors - if your editing/display software can still show you the picture at all - would likely manifest themselves as flawed spots, or odd looking chunks of pixels, sometimes in a pattern. <br /><br />Yes, various data storage devices can show errors over time. The optical media decays, the magnetic patterns on the hard disk start to lose their clarity ... but this won't really show up as images that just don't look as good as they used to. If that's the case, you're probably looking at images that you prepared on older software, or while using a different display, or while editing in a different color space/profile, and which don't look the same to your more experienced current eye, or on more recently configured equipment.<br /><br />Regardless, make a point of refreshing your backups. It's just a bunch of ones and zeros! It's easy, and it gets cheaper every day to but gargantuan disk drives.</p>

<p>Up. It's called digital rot. The very early digital files I shot (before the DSLR craze) are toast. Entire CD's (the best you can buy at the time) cannot be read. </p>

<p>There used to be a program (which I haven't seen for awhile) called something like Sure Write (I think I'm slightly missing it, but Right Way sounds like a large format film back). It would rewrite your ones and zeros, keeping them moved around and charged on the disc so they wouldn't lose their magnetism.</p>

<p>If you are archiving to DVD's make sure you use gold ones that are listed as archival<br>

An article on this : <a href="http://adterrasperaspera.com/blog/2006/10/30/how-to-choose-cddvd-archival-media">http://adterrasperaspera.com/blog/2006/10/30/how-to-choose-cddvd-archival-media</a></p>

 

<p>@Michael, your problem isn't digital rot, it's CD rot. So long as the file can be read without corruption, it will remain the same as when it was recorded.</p>

<p>Any solution that claims to refresh your files is just churning your HD and further fragmenting your files, which leads to degraded drive performance, but not "digital rot"</p>

<p><Chas></p>

<p>Aside from the rare corruption of a file, which is likely to make it unreadable, the typical degradation of image files occurs when it is stored as jpeg, read, and saved (not merely closed.) Each instance of saving a jpg file brings about a new lossy compression, so that the image will degrade visibly if enough reads and saves are performed. This does not happen when lossless compression such as tif is used.</p>

<p>The more likely thing is not that a stored digital image gets worse, but that our opinion of it gets better. When we look at it again, and it hasn't changed, we become convinced that it has degraded.</p>

<p>My early CDs were Gold.</p>

<p>Tudor: Your article is very good, but also properly states that gold is not the be-all, end-all. It is more than just buying gold discs.</p>

<p>Charles: "So long as it can be read without corruption, it will remain the same as when recorded." Yes... and the difference is? I agree, it can fragment files, but you can also unfragment them and reorder them.</p>

<p>Hector: I disagree. Any bit that is recorded can be destroyed. TIF files (thought my favorite for storage because they are a textual representation of an image), are not exempt from "rot". </p>

<p>Here is another good reference for bit rot/data rot: http://en.wikipedia.org/wiki/Bit_rot</p>

<p>I know that for myself, photos that I thought were quite good 10 years ago when viewed on today's much better monitors, they don't look very good. I wonder if the OP is experiencing the same or is it something different.</p>

<p>And a note for those people who use CDs or DVDs for archival. I would immediately make sure that you multiple copies, preferably both on hard drives and in the cloud (meaning on the web). CDs and DVDs can get lost and will burn in a fire.</p>

<blockquote>

<p>Each instance of saving a jpg file brings about a new lossy compression, so that the image will degrade visibly if enough reads and saves are performed.</p>

</blockquote>

<p>I keep reading this - and I want to add that if the JPEG is saved at the maximum quality, I can't detect any degradation and the file size is not reduced, indicating that no further compression has taken place. I just saved the same file ten times and the file size actually slightly increased. I do certainly agree that if a JPEG is saved and re-saved at less than maximum quality, then a visible degradation is observed already after a few saves - of course depending on the actually quality setting used. I save all my JPEGs at maximum quality and reduce the size only when required, for example, to post in a forum or on certain photo sites with size restrictions.</p>

<p>I don't know if it's the same thing or not, but sometimes I find that my pictures are not as good as I remembered them being.</p>

<p>In the old days of physically storing images in negative, prints and slides, there were both benefits and losses from what Marx once called "the gnawing criticism of the mice".</p>

<p>No, digital files do not degrade over time since the data is digital - a series of 0's and 1's.</p>

<p>However, if you convert a digital graphics file (ie, a picture file) from one format to another, the conversion can cause degrading since no graphics file conversion algorithm is 100% perfect.</p>

<p>Also, if you edit a compressed file like JPEG and save it back as a JPEG that can degrade the file.</p>

<p>Or, if you try to resize a graphics file to UP-SIZE it to larger pixeler dimensions than it was before, that can degrade the image.</p>

<p>Also, the viewing monitors you use to view an image can degrade over time, probably not a problem as much for LCDs as the older CRTs.</p>

<p>And, of course, your human eyes - wonderful though they are - can degrade over time (as you age), necessitating a regular visit to your optometrist. That can affect how well you see graphics images.</p>

<p>But left unmodified on a stable storage media, digital graphics files do not degrade, unless acted upon by some editor or some form of electro-magnetic interference or possibly ESD (electro-static discharge).</p>

<blockquote>

<p>No, digital files do not degrade over time since the data is digital - a series of 0's and 1's.</p>

</blockquote>

<p>Alan, I'm sorry, but you're dead wrong. 0's and 1's are not magical, mythical entities. They are zeros or ones because they are electrically charged as such. A loss of this charge (magnetism) will result in a loss of the data.</p>

<p>I'm guessing that the OP Harry was referring to files being opened don't look so great, at least as good as he recalled them, not that he's losing them. If that's the case then the answer to his question would probably be no. Come back Harry and let us know more.</p>

<p>Michael, the wikipedia article to which you refer does not mention the possibility of bit rot on hard disks. Perhaps I overlooked something?</p>

<p><Chas><br /><br /></p>

<p>I don't know it could be I am a little bit more critical, but sometimes it seems like some of the files I saved even on Pnet have lost some of their punch. Then again, it could be they were degraded from the outset ?</p>

<p>Harry,</p>

<p>Do you calibrate your monitor? If so, when was the last time?</p>

<p>I'm not sure if digital files decay over time, but I'm quite positive digital photographers do! :)</p>

<p>I find that pinholes develop over time in my digital files. This is a serious problem and it is even worse when I put the digital files in a color enlarger. I'm tired of the retouching on these prints.</p>

<p>No way, digital files will NEVER degrade - except as pointed already by some folks if it is not lossless JPG file. If you are finding difference in what you saw earlier and what you are seeing today in those pictures, first question is - are you using the same computer hardware and software to view those pictures ? It is quite possible that same file would look different on different computer systems. Just go to bestbuy where different HD TVs are mounted on the huge wall and look at those from distance and you will be notice what I am saying...</p>

 

<p>Digital files do not degrade over time, at least no where near as fast as photographers. ;)</p>

 

<p>I think we need to be careful in our terminology. Digital files most certainly <em>can </em>degrade. When that happens, they become corrupted. Digital images probably don't degrade, unless their digital file (actually all files on disk are digital) degrades or gets corrupted.</p>

<p>Harry, Some sites manipulate the images when they are uploaded. I don't know if PNet does it (though some recent images I uploaded were not as crisp as the file on my computer copy. Facebook used to crunch the file, but I noticed recently they now have a high resolution upload option that seems to look pretty good.</p>

<p>The OP is asking about digital files stored on his computer, not a CD, tape or DVD.</p>

<p>Files can become corrupted, which renders them unreadable in whole or in part. There is a lot of error correction built into a file on an hard drive (CD, tape or DVD), which allows so-called "soft errors" to be recovered completely. If you copy a file with "soft errors", the copy will be perfect. If you have hard errors (uncorrectable), you're going to know it right away.</p>

<p>What you may be seeing is not a degradation of files, but improvements in your skills and expectations. Equipment too has been continually improved, and shots taken with film or earlier DSLRs may not measure up to ones taken with more recent cameras.</p>

<p>Finally, if you do not calibrate your monitor, images you adjusted earlier may not look like ones done more recently. The ones you do today may not look good in the future, nor on anyone else's monitor. If you are serious about digital photography (including scanned film), think about calibrating your monitor on a regular basis, using a suitable measuring device and software.</p>

<p>I don't know if they degrade, but they disappear completely if your drive fails before you back them up.</p>

<p>As someone who works in IT (and has done so for about 30 years) I have heard this argument back and forth for quite a while. It would be really interesting to see whether any long-term studies have been done on files, and whether or not they do lose bits on any kind of regular (or even semi-regular) basis if left on a device, or moved between devices without being manipulated. I am open to believing that could happen, but as I say I haven't heard more than some strongly-worded opinions one way or the other.<br>

Of course, as several people have indicated you have the software/monitor/bad-backup scenarios that can and will directly impact your files. I usually use a copy (without opening) of any file I want to keep long term and work on that copy, so I mostly have the original un-tampered for "keepers". But it is interesting once you start working with a file to see the kind of changes, especially down-sizing, that occur once you start fiddling around with the image.<br>

Anyone have any insight into any studies on this issue?</p>