Why all these tags are added when adding ONLY DateTimeOriginal

[LaurentG]

Let's assume that image is originally free of any tag
I add to it ONLY DateTimeOriginal
   

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exiftool -DateTimeOriginal=20000101120000 image.jpg
As a result, the updated image contains all these tags (and not only the one added) :

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[IFD0]     X Resolution
[IFD0]     Y Resolution
[IFD0]     Resolution Unit
[IFD0]     Y Cb Cr Positioning
[ExifIFD]  Exif Version
[ExifIFD]  Date/Time Original
[ExifIFD]  Components Configuration
[ExifIFD]  Flashpix Version
[ExifIFD]  Color Space

I'm sure there is a good reason for that... but I'd like to understand

[ywzc]

Those are mandatory tags by the Exif 2.32 spec (some of them are no longer mandatory in Exif 3.0). ExifTool adds those automatically with default values when writing exif information if they don't exist. This behavior can be disabled with the NoMandatory api option.

[Phil Harvey]

My thoughts on mandatory tags.

- Phil

[StarGeek]

Previous thread on the subject.

[LaurentG]

Thank you very much to all 3 of you, for these detailed and commented explanations !

I'm using therefore the -api NoMandatory option