How to write custom tag and value to GPS Group?

[Archive]

[Originally posted by janmartin on 2010-01-05 18:55:52-08]

Hi Phil,

I am still trying to create a custom tag in the GPS group and write content to it.

The following does not work yet:

me@me-u904:~$ perl /home/me/scripts/custom_tag.pl

Sorry, MyNewTag is not writable

May I ask for your help?

Thanks,

Jan

Code:

#!/usr/bin/perl
use warnings;

# Most of this file copied from:
# http://cpanforum.com/threads/7404#7424

# ============================== Load modules ====================================
use Image::ExifTool qw(:Public);
my ($picFile);
$picFile = '/home/me/image_001.jpg';

$tagvalue = <<END;
Jipeee, it works!
END
# print $tagvalue;

#define ExifTool object;
my $ExifTool = new Image::ExifTool;

# adapted from https://exiftool.org/config.html

%Image::ExifTool::UserDefined = (
'Image::ExifTool::Exif::Main' => { 0xd000 => { Name => 'MyNewTag', Writable => 'int16u', WriteGroup => 'GPS', }, } );

$ExifTool->SetNewValue('MyNewTag', $tagvalue);
$ExifTool->WriteInfo($picFile);

print "After mod=============================================== \n";
my $info = ImageInfo($picFile);
foreach (keys %$info) { print "$_ => $$info{$_}\n";
 } #end

[Archive]

[Originally posted by exiftool on 2010-01-05 19:10:16-08]

Hi Jan,

It works with this definition:

Code:

%Image::ExifTool::UserDefined = (
    'Image::ExifTool::GPS::Main' => {
        0xd000 => {
            Name => 'MyNewTag',
            Writable => 'string',
        },
    },
);

- Phil

[Archive]

[Originally posted by janmartin on 2010-01-06 14:13:17-08]

Thanks Phil,

now writing the user defined tag works.

However reading the MyNewTag tags content is a different thing:

Firefox Add-On "Exif Viewer" output:

Code:

Exif GPS IFD
...
Unknown tag, Tagnum 0xd000 = data ===> Jipeee, it works!

This is no what I thought of.

Basically I am looking for a way to save a json string in a way that it can be accessed easyly and without tinkering from most programming languages. Especially perl, javascript, actionscript3.

Also I would like to avoid using existing tags, to not overwrite any existing content.

Do you have an idea how to achieve this, please?

Thanks,

Jan

P.S.:

I just added the MyNewTag tag to the source of the jquery library I am using, and now at least that works!

[Archive]

[Originally posted by exiftool on 2010-01-06 14:30:32-08]

Hi Jan,

I would suggest using XMP instead of EXIF if your software supports it.
XMP is designed to be extensible so custom tags are sometimes
handled a bit better than with EXIF.

- Phil