(Modified 2012 Dec 16)
exiftool
I have at times combined photostaken concurrently on different cameras. I had two goals in mind:
To alter the creation date, for cases when I forgot to change the time zone
To sort the files by creation date
exiftool accomplishes both of these tasks. In Ubuntu, it is present in the package libimage-exiftool-perl. I'll start with the second goal first.
exiftool -T -createdate -filename *JPG | sort >! ../exif.txt
-T will create a tab-delimited line with subsequently named EXIF tags
-createdate and -filename are the EXIF tags which will be tab-delimited
the sort step is easier if the date comes first on each line (as opposed to filename)
NOTE: Files that lack these EXIF tags will not be written to the output. Panoramas, for example, may not have such tags, and such outliers may have to be pasted individually.
The syntax for altering the timestamps I adapted from Dimitar Darazhanski's blog and Phil Harvey:
exiftool -s -AllDates CAM_0001.JPG exiftool -DateTimeOriginal+='1:2:3 4:00:0' -CreateDate+='1:2:3 4:00:0' -overwrite_original -preserve -ignoreMinorErrors CAM_0001.JPG exiftool -s -AllDates CAM_0001.JPG
The first step prints out the creation and modification times of the files.
In the second step:
-DateTimeOriginal+='1:2:3 4:00:0' adds 1 year, 2 months, 3 days, and 4 hours to the original timestamp
-CreateDate+='1:2:3 4:00:0' adds 1 year, 2 months, 3 days, and 4 hours to the creation date
I didn't use the -AllDates flag in order to not add to the modification time
-overwrite_original is self-explanatory -- otherwise, an output name would be required
-preserve preserves the modification time
-ignoreMinorErrors supresses some warnings that would have aborted the operation
The third step helps confirm that the previous step worked correctly.
The exiftools manual page has much more information.
This page is Lynx-enhanced