registry team mailing list archive

[Michael Hendry <644125@xxxxxxxxxxxxxxxxxx>]

I've been reading about the EXIF "standard", and it appears not quite to
match up to that description!

One problem is that the tags are identified by number within the image
file, and different applications attach different descriptions to these
numbers.

What seems clear is that there are three distinct date and time tags
(with fractions of seconds in separate tags to go with them): taking one
set of names, DateTimeOriginal is intended to denote the date of
creation of the original object, DateTimeDigitized is for literally
that, the date this digital copy was first made of the object, and
DateTime is the date the file in which the image is contained was last
changed.

Shotwell is built around the idea of "Events", grouping images together
by the date on which they (appear to have) occurred, so it's logical
that DateTimeOriginal should take precedence. If this is absent, then
DateTimeDigitized should be used, as this denotes an "event" in this
image's history, and would tend to group images together in a
chronological sequence (as a length of 35mm still film is scanned in).

My scanner uses DateTime only, and it would be helpful if this could be
picked up in the absence of the other two, and finally there's the
operating system's creation date for the file - which is all you'll get
(for example) in a BMP file.

When I first got my scanner I used it to save the files in BMP format at
maximum resolution, reasoning that this would include all the
information the scanner could get from the image, but as my primary
interest at that stage was the creation of some sort of index of all my
old negatives I cut back the resolution and reverted to JPG to get the
job done in a reasonable time without taking over all my hard disc
space. Promising images can be re-scanned in a higher resolution.

Is there any particular reason why you don't support BMP? I've started
converting them to JPG so as to be able to get Shotwell to see them, but
this is a tiresome chore, and takes up more disc space. (Off-topic, I
know...).

-- 
Date information not imported with jpg files of scanned negatives
https://bugs.launchpad.net/bugs/644125
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