Exif tag and value names - nonstandard usage

CPAN::Forum

Thread

Image-ExifTool [search.cpan.org] [Kobes search] [View and report bugs] [Ratings 4.5

(4) ]

[AnnoCPAN] [CPAN Tests results] [CPANTS]

Posted on Sun Feb 18 13:03:55 2007 by mjc

Exif tag and value names - nonstandard usage

Hi all,

Exiftool doesn't appear to follow the Exif standard for tag names and values. Why? For instance:

[mjc@strawberry eraseme]$ exiftool -s -s -e -n -G1 s_gps.jpg | grep IFD.*Date
[IFD0] ModifyDate: 2002:07:19 13:28:10
[ExifIFD] DateTimeOriginal: 2002:07:13 15:58:28
[ExifIFD] CreateDate: 2002:07:13 15:58:28

These tags are called DateTime, DateTimeOriginal, and DateTimeDigitized respectively in the Exif standard.

Or:
[mjc@strawberry eraseme]$ exiftool -s -s -e -n -G1 s_gps.jpg | grep Meter
[ExifIFD] MeteringMode: 5
[mjc@strawberry eraseme]$ exiftool -s -s -e -G1 s_gps.jpg | grep Meter
[ExifIFD] MeteringMode: Multi-segment

The standard defines "5" as "Pattern".

The standard I'm referring to is http://www.exif.org/Exif2-2.PDF. For the curious, I'm wondering about using exiftool in gThumb (http://bugzilla.gnome.org/show_bug.cgi?id=409050).

- Mike

Direct Responses: 4373 | Write a response

Posted on Sun Feb 18 15:14:36 2007 by exiftool in response to 4372

Re: Exif tag and value names - nonstandard usage

Hi Mike,

To quote the tag name documentation:

"Note: If you are familiar with common meta-information tag names, you may find that some ExifTool tag names are different than expected. The usual reason for this is to make the tag names more consistent across different types of meta information. To determine a tag name, either consult this documentation or run exiftool -s on a file containing the information in question."

ExifTool handles many types of meta information, and attempts to provide a uniform interface across all of these types.

This explains the date tag names, but I don't think it explains the MeteringMode differences. I can't remember now why I named that one specific metering mode "Multi-segment" because that was over 3 years ago when I added that tag, and it is just another name for "Pattern" metering. There may be some things I would name differently now given the experience I have gained over the last 3 years, but unless there is a very good reason to change them I stick with my original choice to provide the best backward compatibility with earlier versions of ExifTool.

I hope this helps.

- Phil

Direct Responses: 4375 | Write a response

Posted on Sun Feb 18 17:45:10 2007 by mjc in response to 4373

Re: Exif tag and value names - nonstandard usage

Oops, I guess I read through that page too fast. Missed that. Sorry!

Anyway: any chance of adding a flag to recall "standards-compliant" tag names? I can see why you would want to rename them for cross-standard consistency, but some users will definitely be annoyed by arbitrary renamings.

- Mike

Direct Responses: 4376 | Write a response

Posted on Sun Feb 18 18:45:03 2007 by exiftool in response to 4375

Re: Exif tag and value names - nonstandard usage

Hi Mike,

I can't think of a way to implement your suggestion easily. It involves introducing yet another option to an already complex user interface, plus the work involved to review 4500+ tags and define all of the "standards-compliant" names.

A lot of work like that can only be justified if a lot of people are "annoyed" by the current scheme, but so far I've had very few complaints.

- Phil

Direct Responses: 7665 | Write a response

Posted on Tue Apr 15 08:38:45 2008 by ignaciogggg in response to 4376

Re: Exif tag and value names - nonstandard usage

Can we change them?

Write a response

Service launched on 2nd of February 2005.
Comments, and other submissions on CPAN Forum are Copyright 2005-2007, their respective owners.
Site maintainer is not responsible for content. Privacy Policy

Maintained and hosted by Gabor Szabo at Perl Training Israel