ExifTool Forum

[Originally posted by b3nj1 on 2007-12-29 05:48:11-08]

I'm just starting out using ExifTool.

ExifTool only shows part of my "OwnerName" field for *some* of my images. On a file that ExifTool shows a partial field, other utilities (eg, IrfanView) show the full field. My OwnerName is the same across all files ("name phone" - which is why I'm interested in ExifTool: to remove that!), so this field's length shouldn't be the problem.

In looking at a few cases (no truncation, moderate truncation, severe truncation), the problem seems related to:
Each case has the truncated character count equal to the MakerNotes base adjustment.

If I overwrite the OwnerName for one of these cases, I get a new Warning:

I've tried version 7.00 and 7.08. I've tried the windows binary as well as the perl source (under cygwin).

Anything I can do about this?

Thanks,
Benjamin

[Originally posted by b3nj1 on 2007-12-29 08:14:51-08]

I should have mentioned that my camera is a Canon 40D. Also, after some more experiments, I think Picasa is the culprit. I have been using Picasa to add IPTC Keywords. Is there anyway to undo the damage it created and ideally preserve the keywords it added?

Thanks,
Benjamin

[Originally posted by exiftool on 2007-12-29 14:21:09-08]

Hi Benjamin,

It is odd that exiftool doesn't fix this problem automatically, since
it should for damaged Canon images.  Picasa must be mangling
the makernotes in some funny way.  If you send me a sample image
I will take a look to see if there is anything you can do to fix this
damage.  My email is philharvey66 at gmail.com.  It may be easier
to put the image on a web server and send me the URL if you can.

- Phil

[Originally posted by exiftool on 2007-12-30 12:41:02-08]

An update after exchanging a couple of emails:

It turns out that when Picasa edits an image it properly updates
all offsets in the Canon makernotes except for the one very
important offset in the makernote trailer which gives the
absolute location of the entire makernote block.  Because of
this, exiftool was incorrectly adjusting the makernote offsets
when reading or writing the image.

The fix was to use the -F0 option with exiftool to
write the image after editing with Picasa.  This repairs the
damage caused by Picasa and allows all makernote information
to be properly displayed once again.

Note that under these circumstances some makernote
information may be lost permanently if exiftool is used to
edit the damaged image without the -F0 option.

- Phil