Date/Time Shift features changes other data

[Leonard WHYTE]

I have a JPG image file.

When I issue 'exiftool "-DateTimeOriginal+=5:10:2 10:48:0" "."' exiftool changes the DTO meta-data tag and nothing else.  File size and other content remains the same.  This is good.
When I issue 'exiftool "-CreateDate+=5:10:2 10:48:0" "."' however, the DTD meta-data tag is updated, but so also is other stuff and the file size changes.  This is NOT what I want.  I just want DTD to be updated.

Is this a bug?  If not, is there a way I can use "exiftool" to modify the DTD tag but make no other changes to the file content?

[StarGeek]

DTD tag?  Are you mistyping DTO (DateTimeOriginal)?  Or do you mean something else?

[Phil Harvey]

This is FAQ 13.

- Phil

[Leonard WHYTE]

Phil, yes I understand that the file size changes when the tags are updated.  But that, as such, is not my concern.

What I'm looking for in a date changer, is the ability to patch the DTD/DTO tags 'in-place' without changing ANY other tags in the image.  I don't want the image re-written, just patched.

Your software does this when updating DTO, but when I update DTD, it ALSO fools with some other tags.  I'm wondering why you do things differently for the DTO and DTD date changes?  I'm looking for a way to update both tags in place. 

Len

[Phil Harvey]

Hi Len,

ExifTool rewrites the entire EXIF if any EXIF tags are changed.  The same goes for XMP and IPTC.

- Phil

[StarGeek]

What I'm looking for in a date changer, is the ability to patch the DTD/DTO tags 'in-place' without changing ANY other tags in the image.  I don't want the image re-written, just patched.

Technically, it rewrites the entire file every time.  It doesn't rewrite 'in-place' or as a patch.  Is that correct Phil?

[Phil Harvey]

For JPEG files the EXIF, XMP and IPTC sections are separate.  So, for example, if no EXIF tags are changed then that section is just copied as a block.  But any section that has changed tags is rewritten completely.

- Phil