Question to some EXIF tags

[herb]

Hello Phil,

searching for some specific values of an EXIF tag on your homepage
   http://www.exiftool.org/TagNames/EXIF.html
I found the following tags with identical tagname but different tagID:

Sharpness             0xa40a and 0xfe56
Saturation             0xa409 and 0xfe55
Contrast                0xa408 and 0xfe54

In CIPA documentation of EXIF v2.3 I only found tags with ID 0xa40a, 0xa409 and 0xa408.

It is not clear to me, where the other IDs do come from?
As all IDs are writable and all belong to ExifIFD taggroup, how will ExifTool differ them, in case they are to be modified?
(Maybe this is a more theoretically problem).

I found these values accidentically and did not a complete search.

Thanks for your comments in advance.
Herb

[Phil Harvey]

Hi Herb,

In the documentation, the underlined tag name is the standard EXIF tag.

There are many non-standard tags, often with the same name as the standard ones.  The non-standard tags are avoided when writing.  That is, they are only updated if they already exist.

- Phil

[herb]

Hello Phil,

thanks for your answer.
But please allow that I repeat it with my own words, in order to be sure to have the correct understanding:

exiftool -exififd:sharpness="sharp-value" imagefile
- will create or modify the standard tag sharpness (0xa40a)
- will modify the non-standard tag sharpness (0xfe56) only in case of it exists and it will also get the value "sharp-value".

exiftool -exififd:sharpness="" imagefile
- will delete both, the standard and the non-standard tag.

Best regards
Herb

[Phil Harvey]

Hi Herb,

Yes, this is how it works.

- Phil