[jira] [Commented] (IMAGING-221) updateExifMetadataLossless restructures meta data (and problems with Maker Notes)

["Joakim Knudsen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IMAGING-221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16853760#comment-16853760 ] 

Joakim Knudsen commented on IMAGING-221:
----------------------------------------

I have set up a project with Commons Imaging (downloaded JAR from apache), and set up the Sample Usage code (WriteExifMetadataExample.java). I have a JPEG with comments and title/description meta data, which is not the output of my code/app. Running this image through the sample code, adding GPS coordinates, it seems the initial meta data is, fortunately, not affected. Looking through the above discussions again, I guess I must have misunderstood; The input to producing the file "mine-gps.jpg" is, perhaps, the file "mine-original.jpg" which does not contain description and UserComment fields?

> updateExifMetadataLossless restructures meta data (and problems with Maker Notes)
> ---------------------------------------------------------------------------------
>
>                 Key: IMAGING-221
>                 URL: https://issues.apache.org/jira/browse/IMAGING-221
>             Project: Commons Imaging
>          Issue Type: Bug
>            Reporter: Joakim Knudsen
>            Assignee: Bruno P. Kinoshita
>            Priority: Major
>             Fix For: 1.0-alpha2
>
>         Attachments: mine-gps.JPG, mine-metadata.JPG, mine-original.JPG, mine.JPG, mine.JPG.html, original.JPG, original.html, tagsmissing.png, test.JPG, test.html
>
>
> ExifRewriter's *updateExifMetadataLossless* method causes the meta data of the JPEG to be completely reordered after writing. This, in itself, might not be a big concern, but it's a bit unexpected when the method is named "lossless". More worryingly, I also find problems are introduced wrt. the Maker Notes tag (odd offset). 
> I've produced an example of the problem in the attached JPEG file, using ExifTool to validate/analyze the images before and after. The image is taken by a Sony Xperia Z5 phone, and the "original.JPG" validates OK. After modifying the contents of the UserComments tag (value: "Test") the modified image produces a warning:
> Verifying the attached photo using ExifTool gives the following output:
> $ ./exiftool\(-k\).exe -validate -warning -a ../test.JPG
> -- press RETURN --
>  
> Validate                        : 1 Warning (all minor)
> Warning                         : [minor] Possibly incorrect maker notes offsets (fix by -628?)
>  
> Using ExifTool's -htmldump option, it is easy to see how the meta data has been affected.



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