When does EXIF data get lost?

Discussion in 'Digital Photography' started by Terry Pinnell, Nov 12, 2004.

  1. I suspect I'm being unduly optimistic in hoping this is a question
    with a relatively simple answer!

    When I browse folders of old photos, I would often like to know the
    precise date and time they were taken. But the EXIF data is missing
    for many. Presumably EXIF info must have existed for *all* of them
    when I first downloaded the DSC000xxxx.jpg images from my Sony
    Cybershot DSC-1 to my PC, but editing has destroyed it?

    Does anyone have or know of an up to date list of all operations by
    specific graphic editing programs which result in such destruction of
    the EXIF data please, so that I can make a point of avoiding them?

    Am I right that although Operation X in Program A might preserve EXIF,
    Operation X in Program B, or Operation Y in Program A (etc) might
    destroy it? IOW, it's something of a mess? If so, I guess the safest
    bet is to keep a copy of those originals, or at least a compact list
    of some sort of their EXIF dates, for future reference if it's
    inadvertently lost?
     
    Terry Pinnell, Nov 12, 2004
    #1
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  2. Terry Pinnell

    Mike Fields Guest

    While I don't have a list (would like to see one though!), some
    editors do lose the EXIF data while others preserve it. Then,
    there is the argument I have heard that if the image is modified,
    the EXIF is no longer valid so should be discarded -- my pref
    would be to see an editor that when you modify an image, leaves
    the original EXIF data, but adds a comment in the comment
    field "modified and the date". Some editors advertise they
    preserve the EXIF data others are silent. Get a utility like
    irfanview (free) http://www.irfanview.com and use it to see
    what the EXIF data is (good program for other stuff too).
    I guess the bottom line is, yes, it is a crap shoot and you need
    to test all of your software used in modifying images to see
    which ones trash the EXIF data for you. I also like to keep
    the originals -- disk space is cheap these days (and make
    backups, but that is another thread in this group !! )

    mikey
     
    Mike Fields, Nov 12, 2004
    #2
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  3. Terry Pinnell

    JHoffnagle Guest

    Older versions of Photoshop, ACDSee, and Paintshop Pro that were not
    EXIF "aware" would not preserve the EXIF data when the image was saved
    after editing/converting/etc.

    The best way to test your various applications is to take an original
    image, rename it, then edit/change it, then save it. Open it again to
    see what hapens to the EXIF data, and document the results. I'd also
    recommend updating/replacing any application that trashes the EXIF
    data fields - in the long run you won't regret it.

    Huffy
     
    JHoffnagle, Nov 12, 2004
    #3
  4. Terry Pinnell

    Bruce Lewis Guest

    I think Huffy is right on with that comment.

    However, if you have some application that you can't update or still
    trashes EXIF information, another step you can take is to rename the
    files with the date/time they were taken. This can be done in a batch
    with the free jhead program. You can also rotate according to your
    orientation sensor with jhead if you've also installed jpegtran.

    Download an example of jhead/jpegtran usage from here:

    http://img.ourdoings.com/windows.html

    (I got the impression you were on Windows. If you're on Linux there's a
    link from there to the Linux version.)

    After you download it, look at the short do.bat file. It shouldn't be
    too hard to modify this batch file to do what you want.
     
    Bruce Lewis, Nov 12, 2004
    #4
  5. Terry Pinnell

    Aerticus Guest

    The moral of the story is:

    1 - DON'T EDIT ORIGINAL IMAGES (leave original prime date prime and
    unmodified)

    2 - only edit or work on copies of the originals (preferably after entring
    IPTC data)

    3 - store data of prime digital images away from and separate to work in
    progress edited copies

    4 - well, all above IMHO

    Aerticus
     
    Aerticus, Nov 12, 2004
    #5
  6. Yes, in my experience that's correct :-(.
    Most likely. I mean, you *could* have run a specific program to
    remove it, but you'd probably remember doing that :).
    No. (Since you carefully asked for a list that's both *complete* and
    *current*, no, nobody has it. But if I'm wrong and you get it,
    forward a copy to me too please?)
    So far as I've found, it's at the program level, not the operation
    level. Although possibly (haven't found an example yet) save
    vs. save-as might give different results.

    I *did* just discover that when Irfanview writes IPTC data (not quite
    the same issue) it appears to delete one field (sub-location) if it's
    present. Bummer. But that's the only single-field example of damage
    to data embedded in image files that I've found. So far.
     
    David Dyer-Bennet, Nov 12, 2004
    #6
  7. Terry Pinnell

    Alan Meyer Guest

    I don't have a list, but I can recommend a kind of solution.

    The free image viewer IrfanView can write out the EXIF data to
    a file. It can even do it in batch mode. If you're able to do simple
    programming in a scripting language it would be very easy to set
    it up to do something like:

    For all files in a directory:
    Extract the EXIF data to a file with the same base name + ".txt"

    You could run this each time you download images from your camera.
    Then no matter what your image editor did to the images, you would
    at least have the text of the original handy.

    But of course you probably still want to save the original images too.

    Alan
     
    Alan Meyer, Nov 12, 2004
    #7
  8. I've been looking for a program that can rewrite that saved data back
    into the jpeg after post processing. closest thing I've found so far is
    called exifer.
     
    Justín Käse, Nov 13, 2004
    #8
  9. Many thanks for all those helpful replies. Following up several of the
    suggested software packages. Looks like I *was* optimistic in looking
    for a no-brainer solution then!
     
    Terry Pinnell, Nov 14, 2004
    #9
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