Title: Display unknowns?
Post by: Archive on May 12, 2010, 08:54:36 AM
Post by: Archive on May 12, 2010, 08:54:36 AM
[Originally posted by rtaylor187 on 2009-05-23 16:19:38-07]
Does EXIFTool have a command that will only display "currently unknown"
metadata fields for any image file?
Occasionally I'm in the mood to go hacking for something new
and such a command would highlight what "isn't currently known"
in an image file. When applied to a series of files it could
be a very useful way to figure out new stuff (or so I imagine :-)
Exiftool currently knows most file fields - for which it is great! -
but that only makes it harder to see what is unknown.
It seems like I could pick out some of that myself by looking
for fields labelled "unknown", but I wonder if that isn't leaving
out some blocks of data that haven't been decoded yet?
A variation would be to show unknown values for known fields.
Thanks!
-= Rich
Does EXIFTool have a command that will only display "currently unknown"
metadata fields for any image file?
Occasionally I'm in the mood to go hacking for something new
and such a command would highlight what "isn't currently known"
in an image file. When applied to a series of files it could
be a very useful way to figure out new stuff (or so I imagine :-)
Exiftool currently knows most file fields - for which it is great! -
but that only makes it harder to see what is unknown.
It seems like I could pick out some of that myself by looking
for fields labelled "unknown", but I wonder if that isn't leaving
out some blocks of data that haven't been decoded yet?
A variation would be to show unknown values for known fields.
Thanks!
-= Rich
Title: Re: Display unknowns?
Post by: Archive on May 12, 2010, 08:54:36 AM
Post by: Archive on May 12, 2010, 08:54:36 AM
[Originally posted by exiftool on 2009-05-23 22:52:15-07]
Hi Rich,
There is so much unknown information for many models that
simply removing known tags from the output wouldn't be
as useful as you think. However, this can be approximated
with "exiftool FILE | grep 0x".
I find the best way to discover new information is to compare two
images like this:
(or if you are really brave, -U instead of -u.)
If you know the shooting conditions for each image, you can
decode a lot of new tags like this.
Another very useful technique is to apply this to a whole set
of images, and look for changes in a specific tag, like this:
I commonly cycle through a set of files like this to see if
any of the unknown tags have values that change in a way
that makes any sense. You repeat the "grep" command for
each unknown tag. Here I used the Pentax_0x003d tag
for an example. If you are on Linux or Mac, the "grep" and
"diff" commands come with your system. If you're in Windows,
you'll have to find a source for these utilities, but I'm sure
they are available.
To show unknown values for known fields, I grep for
the string "Unknown" in the output.
Maybe doing something like this will get you going.
I would be happy to hear if you discover anything new.
- Phil
Hi Rich,
There is so much unknown information for many models that
simply removing known tags from the output wouldn't be
as useful as you think. However, this can be approximated
with "exiftool FILE | grep 0x".
I find the best way to discover new information is to compare two
images like this:
Code:
exiftool -a -u -G1 > t1
exiftool -a -u -G1 > t2
diff t1 t2
exiftool -a -u -G1 > t2
diff t1 t2
(or if you are really brave, -U instead of -u.)
If you know the shooting conditions for each image, you can
decode a lot of new tags like this.
Another very useful technique is to apply this to a whole set
of images, and look for changes in a specific tag, like this:
Code:
exiftool -a -u -G1 -w tmp/%f.txt DIR
grep -r "Pentax 0x003d" tmp
grep -r "Pentax 0x003d" tmp
I commonly cycle through a set of files like this to see if
any of the unknown tags have values that change in a way
that makes any sense. You repeat the "grep" command for
each unknown tag. Here I used the Pentax_0x003d tag
for an example. If you are on Linux or Mac, the "grep" and
"diff" commands come with your system. If you're in Windows,
you'll have to find a source for these utilities, but I'm sure
they are available.
To show unknown values for known fields, I grep for
the string "Unknown" in the output.
Maybe doing something like this will get you going.
I would be happy to hear if you discover anything new.
- Phil