Error in docs about "file creation date"
Wilhelm Sanke
sanke at hrz.uni-kassel.de
Mon May 21 15:00:59 EDT 2007
First a word of thanks to Jacqueline and Jim Ault for their patience
with which they try to help finding out what is going on behind the scenes.
I think I know now where Rev is looking for date information with the
detailed files on WindowsXP.
There are fours kinds of date data with image files, and three for all
other non-image files.
For image files they are:
- date of taking the photo
- creation of file
- modification of the file
- date of last access to the file
If you customize your folder accordingly, the date informations are
displayed in the following order: Modification, photo taken, created,
last access.
The date when the photo was taken is also displayed in the tooltip when
you move the mouse cursor over the image file. Then you have a
properties pane for each file which you open with right-click on the
file. From this pane you can inspect the EXIF data - if there are any -
and also look at creation, modification, and last-access dates.
From these 4 categories of date information the detailed files access
two, namely creation of file and modification of the file.
Now, one important aspect of the date informations is how they are
related to each other. This is where some difficulties of understanding
may arise - as in my case.
When a photo is taken, it gets a modification date at the same time,
although it is - as it were - only modified out of non-existence.
The creation date is generated when the image arrives on the computer,
and a new creation date is generated each time the image is saved or
copied. Simply "moving" an image to another folder does *not* change the
creation date.
This leads to the at first glance puzzling effect that the creation date
is normally a later date than the modification date, the latter of which
may even still be identical with the date the photo was taken, i.e. when
it was really created as a photo.
Thus in the majority of cases, what passes as modification date in the
detailed files is the nearest you can get to the date the photo was taken.
Creation date and date of photo taken can only be identical when the
picture is transferred from the camera to the computer on the same day
the photo was taken.-
This all holds for WindowsXP and probably to some extent for MacOS, too.
But this does not explain the "phantastic" date of "Jan 18, 2038" which
I got for the creation date - item four of the detailed files - when I
transferred files to my Powerbook with an USB stick.--
What should the Rev "quality team" do in this matter? At least explain
in the docs that the detailed files make no use of the EXIF data (which
would indeed be accessible on WindowsXP) and describe in some plain
words the specific nature of the "creation" and "modification" dates
retrieved by the detailed files.
The best way of course would be to add the real-photo-creation date from
the EXIF data to the detailed files, such an additional item of the
detailed files could then return empty when no EXIF data are available -
as in the case of other items when no information matches such an item.
I think I should submit an enhancement request, and for the time being I
will use the modification date in my thumbs stack.
Best regards,
Wilhelm Sanke
<http://www.sanke.org/MetaMedia>
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