Author Topic: Problems with photoshop-files  (Read 4655 times)

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Problems with photoshop-files
« on: May 12, 2010, 08:53:49 AM »
[Originally posted by linuxuser on 2005-06-01 18:33:47-07]

As mentioned in an other posting, there are problems reading the exif-data of
some Photoshop-files. It looks like that all versions after PS 6 have this
problem.

I got different tiff- and jpg-files from friends, who uses Photoshop and we
found out, that with Photoshop Elements 2, 7 and CS exif-info is changed in a
way, that it is unreadable by exif (sourceforge.net/projects/libexif) or
doesn't show parts of the exif-info. Exif.py shows a little bit more (I read
it is unmaintained). Exiftool works best, but produces sometimes errors,
which probably can be ignored. ImageMagick (identify) produces errors, when
reading these modified files. It looks like that klibexif does a better job
with these problem files than libexif, because it shows some exif-data, where
exif can't read data.

I know that this is a board for exiftool, but I told you the behaviour of
other exif tools, because it could be helpful.

I found out, that especiall fields after "Photoshop Settings : (Binary data
1450 bytes, use -b option to
extract)" could be missing, like Shooting Date/Time

At the moment I cannot give away a sample file, because I do not have to right
to give it away. But I think you should be able to test it yourself. I tested
with my own files now and didn't get an error at the moment. Since I use
"2&gt/dev/null 1&gt/dev/null" in the meantime with exiftool, I don't notice these
errors anymore. Maybe exiftool does something, that the error doesn't occur
if you try to modify exif a 2nd time.

Now I got one with with identify
tif: unknown field with tag 34665 (0x8769) encountered
I know this isn't an exiftool error, but maybe it helps. This ExifOffset I got
with exiftool too with a file I don't remember anymore.

This should produce the error:

Take a picture with a camera and store in tiff and another one in jpeg-format.
Of course exif-data has to be supported by this digicam.

Use a _"newer"_ Photoshop.

Modify this picture with PS, like changing colors, unsharpen, a.s.o.

Store it in the same format as the original format. We tried for jpeg with
baseline optimized, quality 11, for tiff with zip compression.

Compare the exif-output before and after the modification, especially after
writing exif-data to these jpg- and tiff-files.

Hope this helps, otherwise let me know, what I can do for it, of course I am
trying to get a picture, where this behaviour is reproduceable.

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Re: Problems with photoshop-files
« Reply #1 on: May 12, 2010, 08:53:49 AM »
[Originally posted by exiftool on 2005-06-01 22:13:53-07]

The newer photoshop versions (ie. PS CS) write meta information in XMP format.  I would guess that this is why tools like libexif can't read it.

Photoshop does not copy all meta information when it rewrites a file.  Much information is lost and can not be recovered.  Photoshop simply doesn't write it all.  This is a well known problem with Photoshop.  Is this what you are talking about, or is ExifTool not reading all the information that you believe is in the file?  I really still don't quite understand the problem.  I don't own PS CS so I can't do the test you mentioned.

About the older Photoshop files:  It really sounds like they are being written incorrectly due to the fact that other utilities also have problems with them.  ExifTool will usually spit out a warning if it encounters a problem, but will continue attempting to parse the file.  Sometimes, depending on the type of problem, ExifTool may refuse to write information to a file that contains errors, but it looks like this isn't happening in this case.  I would still like a sample image if you can come up with one.

(BTW, try using <p>

 to format your text into paragraphs.)</p>

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Re: Problems with photoshop-files
« Reply #2 on: May 12, 2010, 08:53:49 AM »
[Originally posted by linuxuser on 2005-06-02 11:04:00-07]

It's hard to understand, why libkexif1 does work better than libexif10. Does exiftool use libimage-exif-perl?

Can I assume that exiftool shows _all_ info, when used with -v4?

Sorry, that I am talking a lot of other apps, but with these programms I made my experiences and in the meantime I made a lot of workarounds, and it is hard for me at the moment, what happens, because exiftool has written a tag. I have to do tests without using exif, or Imagemagick before.

A while ago I did a test with ImageMagick, which shouldnt loose exifinfo after convert and found out, that the following fields are lost with the following command, if it is a photoshop modified file

convert -fuzz 25% -trim -shave 25x25 -page +0+0 original.tiff miff:- | convert -quality 95 -page +0+0 - shaved.tiff

Subfile Type

Strip Offsets

Shooting Date/Time

Color Space

Exif Image Width

Exif Image Length

Date/Time Digitized

Creator Tool

Application Record Version

When I have time I will do more tests with exiftool, and compare what happens, after exiftool changes data.

In the meantime I am unsure, what really happens. For sure I know now, that ImageMagick 6.0.6 05/26/05 Q16 cannot read some exif-data, although exiftool can, if files were modified with PS

I will try to get a sample image for you and then do tests with it. Please give me time. It could take a week.

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Re: Problems with photoshop-files
« Reply #3 on: May 12, 2010, 08:53:49 AM »
[Originally posted by exiftool on 2005-06-02 11:36:59-07]

> Can I assume that exiftool shows _all_ info, when used with -v4?

This is  usually overkill, and is mainly used when trying to decode new information.  "-v4" doesn't convert the information to a readable form.  Use "-a -U -G1" to show all info in a readable form, and the location where it was found.  Either will show all information from meta information formats supported by ExifTool.

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Re: Problems with photoshop-files
« Reply #4 on: May 12, 2010, 08:53:49 AM »
[Originally posted by linuxuser on 2005-06-02 11:43:32-07]

Thanks, to compare files I used till now -v4 and then diff. Till now I am not so familiar with the combination of options. Maybe you can put such hints to the examples in the manpage too.

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Re: Problems with photoshop-files
« Reply #5 on: May 12, 2010, 08:53:49 AM »
[Originally posted by exiftool on 2005-06-02 11:55:38-07]

The FAQ (https://exiftool.org/faq.html) suggests using "-a -G1" which is a useful combination.  I threw in the '-U' to also display unknown information.

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Re: Problems with photoshop-files
« Reply #6 on: May 12, 2010, 08:53:49 AM »
[Originally posted by linuxuser on 2005-06-02 12:02:36-07]

When I tried some (maybe stupid) combinations of the options, it could be, that there was no result. So I stopped using more than 1 option most times, my fault, not to remember this sample, sorry.