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'?' appended to every exif comment

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    '?' appended to every exif comment

    With DVD Slideshow GUI I've tried to create a slideshow out of a few jpg images, with subtitles taken from their exif comments. Every image has been modified with IrfanView 4.00 - resized, enhanced, and given some comment (Image - Information - Comment).

    To my surprise, each subtitle displayed by DVD lideshow GUI had '?' as the last symbol (without quotes), although I didn't put them there.

    My first thought was there had to be something wrong with DVD Slideshow GUI. I described the problem on their forum, http://forum.videohelp.com/viewtopic...850447#1850447, and got a quick answer from the author. He suspected inconsistencies of the exif data format, and provided a link to jhead (http://www.sentex.ca/~mwandel/jhead/) - a program used in DVD Slideshow GUI to extract exif data from images. I tried jhead on my images, and indeed, every comment comes up with '?' appended. Jhead also allows all sorts of exif modifications, including modifications of comments. Comments written by means of jhead don't have any '?' at their ends.

    Why does IrfanView append '?' to comments that are edited in the box resulting from clicks on Image - Information - Comment?

    Best regards,
    --
    Jack

    #2
    Hi Jack,

    I tried to reduce, enhance, add comment and save, but I couldn't see appended ? to EXIF. Though I used IrfanView and other programs to read EXIF.
    Please explain what I should do to reproduce that, especially how I should use Jhead.

    Laurent
    Last edited by Laurent; 25.05.2008, 04:50 PM. Reason: Spelling
    Before you post ... fill in your OS and IV version in your profile.

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      #3
      Thanks Laurent for your reply.

      Try the following experiment on a WinXP system:

      1. In IrfanView, create an image 100*100 of any color, and save it in t1.jpg and t2.jpg.
      2. Still in IrfanView, put the string IrfanView into the Coment field of t1.jpg and save it.
      3. Get jhead.exe (prebuilt windows executable) from http://www.sentex.ca/~mwandel/jhead/, and place it on a path to executables.
      4. In a command window, run:
      jhead t1.jpg
      on my system the results are:
      File name : t1.jpg
      File size : 371 bytes
      File date : 2008:05:26 08:28:40
      Resolution : 100 x 100
      Comment : IrfanView?
      jhead -cl Jhead t2.jpg
      it inserts Jhead as a literal comment string into t2.jpg,
      jhead t2.jpg
      on my system the results are:
      File name : t2.jpg
      File size : 366 bytes
      File date : 2008:05:26 08:52:14
      Resolution : 100 x 100
      Comment : Jhead
      5. For t1.jpg and t2.jpg, see how IrfanView displays their comments. On my system, they are IrfanView and Jhead respectively, without any question mark or missing characters.

      What other programs did you use to display Exif?

      Best regards,
      --
      Jack
      Last edited by jaceko; 26.05.2008, 08:13 AM. Reason: better formatting

      Comment


        #4
        Hi Jack,

        I tried with a copy of a picture taken with my digital camera.

        Initially, it contained an EXIF comment and no JPEG comment. Jhead returned the EXIF comment. I could notice that IrfanView displays much more EXIF data than Jhead returns.

        Then I used Image | Information | Comment, entered "IrfanView" in the dialog box, wrote it to the JPEG and exited IrfanView. Jhead returned the same comment as before (EXIF info, not JPEG info). I reopened the image with IrfanView. The comment was still tere.

        After that, I entered "jhead -cl Jhead test.jpg" at the command prompt. I got the message "Modified: test.jpg". IrfanView displayed correctly the new JPEG comment but Jhead still displayed the old one.

        It looks like Jhead displays the JPEG comment only if there is no EXIF comment. If there is an EXIF comment, then Jhead ignores the JPEG comment.

        From IrfanView, I cleared the EXIF data and then, eventually, I was able to reproduce the problem. The "?" was there.

        Then I did a last try, with the GIMP. No "?" there.

        So I am not certain the problem is in IrfanView.

        Laurent
        Before you post ... fill in your OS and IV version in your profile.

        Comment


          #5
          Hi Laurent,

          It's becoming interesting, isn't it?

          Jhead has a lot of various options, all listed with 'jhead -h'. I haven't explored them too thoroughly. Probably it is capable of displaying all of exif data, and jpeg comment as well.

          As a matter of fact, I didn't realize that jpeg and exif comments were different things. IrfanView doesn't seem to allow any modifications of exif comments.

          How do you display/modify comments in Gimp?

          Best regards,
          --
          Jack
          Last edited by jaceko; 27.05.2008, 01:17 AM. Reason: wrong word corrected

          Comment


            #6
            Originally posted by jaceko View Post
            IrfanView doesn't seem to allow any modifications of exif comments.
            No, IrfanView doesn't allow modifications.

            How do you display/modify comments in Gimp?
            Alt+Enter (the command is something like Image | Properties; free translation from french version) and look in the third tab (something like Comments). These are the JPEG comments. Edit if needed and save the file.

            Laurent
            Before you post ... fill in your OS and IV version in your profile.

            Comment


              #7
              Many thanks, Laurent. You've been very helpful.

              Gimp seems to deal with question marks inserted into jpeg comments by IrfanView in a rather surprising way. It doesn't display them in the Image - Image Properties - Comment box. Moreover, it seems to remove them automatically just by closing the box and saving the image. I have just tested it with jhead: '?' was there before saving, and was absent after saving.

              I think the problem of '?' at the end of jpeg comments written by IrfanView needs to be resolved.

              Best regards,
              --
              Jack

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