[Shotwell] EXIF data contained in JPEG image files

[Alex Janssen]

On 09/27/2011 04:49 PM, Jim Nelson wrote:
> I took a photo, modified it in direct-edit mode, and saved it.  I then 
> ran this command for each:
>
> $ exiv2 -pa IMG_0001.JPG > orig.txt
> $ exiv2 -pa IMG_0002_saved.JPG > saved.txt
>
> Then I did a diff (using meld) of the files.  I see no changes other 
> than a couple expected modifications.
>
> What do you see when you do this experiment?
>
> -- Jim

I finally got around to running your experiment and I saw just what you 
expected me to see as follows.

    $ diff orig.txt copy.txt
    7c7
    < Exif.Image.Software                          Ascii      10  Ver.1.0
    ---
     > Exif.Image.Software                          Ascii      15 
    Shotwell 0.9.3
    10c10
    < Exif.Image.ExifTag                           Long        1  418
    ---
     > Exif.Image.ExifTag                           Long        1  424
    26c26
    < Exif.MakerNote.Offset                        Long        1  908
    ---
     > Exif.MakerNote.Offset                        Long        1  914
    65,67c65,67
    < Exif.Photo.PixelXDimension                   Long        1  848
    < Exif.Photo.PixelYDimension                   Long        1  480
    < Exif.Photo.InteroperabilityTag               Long        1  7690
    ---
     > Exif.Photo.PixelXDimension                   SLong       1  703
     > Exif.Photo.PixelYDimension                   SLong       1  312
     > Exif.Photo.InteroperabilityTag               Long        1  7696
    84,91c84,90
    < Exif.Thumbnail.Compression                   Short       1  JPEG
    (old-style)
    < Exif.Thumbnail.Orientation                   Short       1  top, left
    < Exif.Thumbnail.XResolution                   Rational    1  72
    < Exif.Thumbnail.YResolution                   Rational    1  72
    < Exif.Thumbnail.ResolutionUnit                Short       1  inch
    < Exif.Thumbnail.JPEGInterchangeFormat         Long        1  8084
    < Exif.Thumbnail.JPEGInterchangeFormatLength   Long        1  4027
    < Exif.Thumbnail.YCbCrPositioning              Short       1  Co-sited
    ---
     > Xmp.exif.PixelXDimension                     XmpText     3  703
     > Xmp.exif.PixelYDimension                     XmpText     3  312
     > Xmp.exif.DateTimeOriginal                    XmpText    20 
    2011:08:31 23:03:18
     > Xmp.exif.DateTimeDigitized                   XmpText    20 
    2011-08-31T23:03:18Z
     > Xmp.tiff.ImageWidth                          XmpText     1  1
     > Xmp.tiff.ImageHeight                         XmpText     3  312
     > Xmp.xmp.CreateDate                           XmpText    20 
    2011-08-31T23:03:18Z

I got no idea, now, how I came to think it was deleting camera and other 
data, but I was sure it was.  I am glad to have run this test.  I have 
more confidence in Shotwell, now, and it is faster and easier than 
firing up GIMP for such simple edits.
Thanks for your help, Jim.

Alex

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