Do Digital files degrade with time ?

Discussion in 'Digital Darkroom' started by hjoseph7, Jan 31, 2011.

  1. 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 ?
     
  2. 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.
     
  3. 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.

    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.

    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.
     
  4. 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.
    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.
     
  5. @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.
    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"
    <Chas>
     
  6. 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.
    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.
     
  7. My early CDs were Gold.
    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.
    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.
    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".
    Here is another good reference for bit rot/data rot: http://en.wikipedia.org/wiki/Bit_rot
     
  8. 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.
    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.
     
  9. 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.​
    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.
     
  10. 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.
    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".
     
  11. No, digital files do not degrade over time since the data is digital - a series of 0's and 1's.
    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.
    Also, if you edit a compressed file like JPEG and save it back as a JPEG that can degrade the file.
    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.
    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.
    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.
    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).
     
  12. No, digital files do not degrade over time since the data is digital - a series of 0's and 1's.​
    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.
     
  13. 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.
     
  14. Harry, perhaps you are a better photographer today than what you were in days gone by. Your tastes may have changed and you might have a more critical eye. It's possible.
     
  15. Michael, the wikipedia article to which you refer does not mention the possibility of bit rot on hard disks. Perhaps I overlooked something?
    <Chas>
     
  16. 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 ?
     
  17. Harry,
    Do you calibrate your monitor? If so, when was the last time?
     
  18. I'm not sure if digital files decay over time, but I'm quite positive digital photographers do! :)
     
  19. Spearhead

    Spearhead Moderator Staff Member

    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.
     
  20. 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...
     
  21. Digital files do not degrade over time, at least no where near as fast as photographers. ;)
     
  22. I think we need to be careful in our terminology. Digital files most certainly can 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.
    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.
     
  23. The OP is asking about digital files stored on his computer, not a CD, tape or DVD.
    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.
    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.
    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.
     
  24. I don't know if they degrade, but they disappear completely if your drive fails before you back them up.
     
  25. 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.
    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.
    Anyone have any insight into any studies on this issue?
     
  26. I may be as paranoid as the next guy, but I believe in at least three backups and I agree completely about archiving the original and never working on that file, but only copies. My practice is to load the original and do an immediate save as, for my working file. That way I am working from the original (of course there is also backups of the original, original that does not get touched). With some images I may save a number of intermediate stages in order to return to them. I have some images with over a dozen versions saved.
    One word of caution about hard copies (DVDs and CDs) -- these are fragile formats and not stable as one might think. Minor physical damage can make files unavailable for recovery. I have learned this the hard way. Further, they can be otherwise lost or damaged, just as old negatives can. Nothing is foolproof. I make multiple copies on multiple drives in multiple places.
     
  27. Just remember John that just because you are paranoid does not mean that someone (or something) is NOT out go get you. A little paranoia can be a valuable thing.
     
  28. Some of my digital photos are looking a bit more sepia tinted these days, probably because I did not save them on acid free CDs.
     
  29. While digital data doesn't deteriorate and digital files will remain identical as long as they are not altered, when it comes to digital images, display, and print technology, we still don't have reliable means to preserve color consistency over time. The best color management can currently do is to help with matching images from one device to another at a certain point in time with the final approval being dependent on the creator or the person in charge.
    This means that if you are a creator who approves the final appearance of an image based on a display or print device, currently there are no means that can assure exact reproduction in the future. In that respect a digital image may live longer as a long lasting print than digital file.
     
  30. 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 ?

    The poster is talking about previous saved photo files (ie, digital graphics files) on the local hard-drive. The unspoken assumption is that the computer is functioning correctly, including the hard-drive storage media, and there have not been any catastrophic failures that might have corrupted hard-drive files.
    As one poster mentioned, file corruption (not degradation) can occur to just about any kind of computer file, not just image files. If a file is corrupted you usually find out about it the next time the system tries to read and 'process' that file. You will see an error message or the file will simply malfunction. The evidence of the corruption is different because there are a LOT of different types of file formats.
    For example, file corruption can occur if you are in the middle of editing a file (document, diagram, image file, spread-sheet, what have you) and suddenly you lose AC power. Unless your system is plugged into an UPS unit or UPS outlet, the system will instantly 'crash', usually with no warning, and no opportunity to save your data first. (This possibility was the motivation for the admonition often given to 'users' - storm approaching! save your data!).
    File corruption could also occur if your hard-drive experienced a "hardware failure", which is possible since they are complicated electro-magnetic-mechanical devices. Sometimes the failure was catastropic, causing the whole system to crash and fail to reboot. Other times, it was simply the development of 'bad spots' in the magnetic media surface, and any data in those bad spots was lost or at best corrupted. You would not know it till you tried to access that file and then you would discover it. Then you would have to run a salvage or disk-check program on the entire hard-drive to discover the true extent of the corruptions and make repairs, if possible.
    Its also concievable that faulty RAM chips can cause file corruption since the OS will load files into RAM before editing.
    If you are running a Windows system, and you suspect any kind of file system corruption, you can always schedule a Disk Check by going under My Computer, right-clicking on the chosen hard-drive, select Properties, then Tools, then Error-Checking. Select all the options on the Error-Checking box so Windows will perform all its Disk-Checks. The disk check will run right away (if its not the C drive), but a reboot is necessary if it is the C drive. The resulting Disk Check will go through the entire file system and check all the tables, indexes, files, folders, security descriptors and yes, even file contents, to see if it sees any corruption, or perhaps "inconsistencies", that need fixing.
    Its not a bad idea to do this once a month on your Windows system, along with regular routine Defrag runs, say once a week.
    I say all that just to clarify what file corruption means in the normal 'IT' sense of the word.
    To my mind the word 'degrade' means something that is undergoing a process of being broken down from its original state to something different.
    The poster seems to be asking if photo files stored on the hard-drive left on their own undergo this type of change.
    And I still think the answer to that question is no, they do not degrade - assuming the storage media they are written to remains functional and uncorrupted. There are numerous types of storage media. And each has its own set of specs about shelf-life, safe storage requirements, how to protect it from damaging outside interference, etc, etc.
    Having said all that, I will equally allow that modern computers and graphics file editing programs and algorithms are quite complicated and inter-linked. You can have a glitch in the system somewhere (hardware or software or operator) and files can end up getting corrupted when you are 'handling' them. They can be simultaneously OK on the hard-drive and yet get 'corrupted' on a piece of backup media. ((I had this happen to me not too long ago with a perfectly good set of JPEG pics. I made a routine dvd data disk of these pics, and when I went to show them to the client, boom, I discovered every one of them on the dvd were corrupted. Just goes to show you, no matter how 'modern' a system you have, and no matter how much 'experience' you have, data glitches can and will still occur. But I call that an unexpected system glitch resulting in a failure to make a good disk. I dont call it a file degradation. Further checks revealed the original Jpeg files, stored on the hard-drive, were just fine, and everything looked OK.))
    Finally, I think there is the real possibilty that some image editing software programs can make internal changes to the contents of your original camera picture file w/o telling you about it. The internal contents of the picture file will certainly be changed if you perform a conversion from one file format to another, say from RAW to TIFF. Or from TIFF to JPEG. But this is not a case of the file degrading by itself, its more a case of an outside force, the editor & operator, making changes to the image file which alters the original digital file.
    And even the whole question about whether an image is degrading involves human memory and human psychology, because you are comparing how the images looks to you today, with your image-memory of how it looked 2 years ago, or something like that.
    So, I still think the answer is no, unless the file is acted upon by some outside action, a digital photo file, correctly saved to a good hard drive, is not going to degrade all by itself.
     
  31. The file itself will not degrade over time, but the media (CD/DVD) upon which you have it stored may, which may ultimately result in a lost file.
     
  32. I suppose a person's monitor can slowly degrade or possibly you have a new monitor that works better making the old picture look worse. . All sorts of stuff could be the cause. However I do not know how long a digital file will last without problems. I suppose a hard drive could be failing. They probably have a lifespan but I would not know what it is. I do not think anyone is using CD's for storage as they don't work well at all. I have not burned a CD for any reason in several years. I would not buy a music CD either, but that is a different story.
     
  33. No, only digital photographers.
    (sorry, couldn't resist - he says as a digital photographer himself)
     
  34. The OP doesn't have a corrupted or lost digital file, otherwise he will not be able to see it at all and talk about differences
    Assuming he is using the same software and setup, his problem is wrong expectation. As I was trying to suggest in my previous post, - you can't relay on display technology and color management to display a digital image over a period of time identically.
    And because of this no one can tell if the difference is a result of a psychological perception, display differences, or both.
     
  35. I use to make 2 DVD copies of all my pictures. The idea was if one went bad, I'd have the other. Then I realized I was keeping both copies together so that if there was a fire, they'd both go. I suppose I could give one copy to a relative to safekeep, but then I realized most of my pictures weren't really that important anyway. So now I make one backup copy in case my computer fails which all of mine have at some point. If a few pictures on that DVD or the whole DVD goes, my life will go on.
     
  36. Yes in a sense that your standard for good photos rises...over time
     
  37. With respect, maybe the problem is with your eyes and not the technical equipment. See an optometrist.
     
  38. Do digital files degrade with time? I really do not know. I have been keeping digital files for 5 years and have not noticed any degradation. I keep Raw images with a JPEG thumbnail on DVD and external hard drive. I am not about to tell you what I think without any facts to back it up. However, I would bet my life that a saved RAW file will not degrade as fast as film!
     

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