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https://issues.apache.org/jira/browse/IMAGING-221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16839259#comment-16839259
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Bruno P. Kinoshita commented on IMAGING-221:
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>However, does the reordering come from "internal" Imaging code, or "external"
>code (i.e. the code used to invoke/call Imaging)?
I believe the reordering comes from internal Imaging code. No dependencies in
Imaging (other than those used for testing). So the only code changing metadata
and data is in our own project.
>And, finally, does such reordering matter at all?
Should not matter IMO. As far as I know, the standards specify data containers
such as directories, segments, fields, etc. And they allow users to organize
them sequentially by providing offsets. But without enforcing that one field
comes before the other. There are segments that may need to come before, but I
haven't seen any issues with that in Imaging.
I believe it would be easier for you to use the code if the metadata order was
kept in place. I haven't investigated where/why it happens.
> 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.JPG, mine.JPG.html, original.JPG, original.html,
> 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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