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

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: 1.0.0-alpha6
• Assignee: Bruno P. Kinoshita
• Reporter: Joakim Knudsen
• Created: 10/Mar/19 22:38
• Updated: 18/Apr/24 14:54

Description

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.