Puzzling file date taken entry

Not something to lose sleep over, but I'm puzzled by this. Looking at
a dozen JPG images I scanned in 2 days ago in a Windows Explorer
folder, just one of them has a 'Date Picture Taken' entry against it.
FWIW, it's 30/11/2005 17:54, and the Date Modified is 30/11/2005
17:55. The files include various edits, such as resizing, removing
moire patterns, softening, unsharp mask, etc, with PaintShop Pro 8 and
IrfanView. But I haven't opened any of them with EXIFER or anything
like that.

So how could that possibly arise please?

--
Terry, West Sussex, UK

Terry Pinnell wrote:
Not something to lose sleep over, but I'm puzzled by this. Looking at
a dozen JPG images I scanned in 2 days ago in a Windows Explorer
folder, just one of them has a 'Date Picture Taken' entry against it.
FWIW, it's 30/11/2005 17:54, and the Date Modified is 30/11/2005
17:55. The files include various edits, such as resizing, removing
moire patterns, softening, unsharp mask, etc, with PaintShop Pro 8 and
IrfanView. But I haven't opened any of them with EXIFER or anything
like that.

So how could that possibly arise please?

Files can have up to three date fields under NTFS - created, modified and
accessed. It's possible that your scanning software saves the file as it
goes along, so the created date may be the start of scan, and the modified
date the end of scan. I don't know how the "Picture taken" display is
derived. I would rather have thought from an EXIF header, but perhaps
from the creation date otherwise?

I owuld have thought that the modification date should be the time of the
last file write, though.

David