Confused over photo Date fields

[Terry Pinnell]

Can anyone help me get my mind around the various date fields for JPG
photo images that are displayed by WinXP and various programs please?
Take this single file as an example (taken by my son on his mobile
phone camera).

FILENAME
--------
xyz description-2005.07.08-00.09.11.jpg
Note: I think that date suffix was added automatically when the photo
was uploaded to a web page.

EXPLORER
-------
'Date Picture Taken' 07/07/2005 14:48
'Date Modified' 19/07/2005 09:22

EXIF
----
'DateTime' 2005:07:08 08:05:38
'DateTimeDigitized' 2005:07:07 14:48:40
'DateTimeOriginal' 2005:07:07 14:48:40

So there are 4 date/time values here, raising various questions:

1. What is the difference between Original and Taken?
2. What is the difference between Original and Digitized?
3. What process could determine that date/time suffixed to the
filename?

Any insights into this would be appreciated please, as I've struggled
to grasp these distinctions and never come up with definitive answers.

 

[Yves Alarie]

In XP, Details view you can have many columns.
So, you need the columns:
Date Created: This the date the file was created on the hard drive, that is
the photo was copied from the camera to the hard drive.
Date Modified: Any editing done to this photo after transferring to the hard
drive.
Date Picture taken: information taken from the Exif file of the photo. This
is the what you want as far as establishing the date and time the photo was
taken.
If you do not have the Date Picture taken column, right click on a column
header. A list will open, click on More at the bottom of the list and click
on Date Picture Taken on the opening list.

"Date Time Original" and "Date Time Digitized" should be exactly the same
and this is what you have and this should correspond to the listing by
Explorer under Date Picture Taken.

As for the "Date Time", I don't know.

 

[Terry Pinnell]

In XP, Details view you can have many columns.
So, you need the columns:
Date Created: This the date the file was created on the hard drive, that is
the photo was copied from the camera to the hard drive.

Thanks, but I'm afraid you're mistaken - it is not. I deliberately
left it out of my example as it's such a misnomer. It always appears
to be either the Date Modified, or an even later date if the folder
was copied elsewhere etc. You would be right only in the rare case
that you've never modified or moved the originally downloaded file.

Date Modified: Any editing done to this photo after transferring to the hard
drive.
Date Picture taken: information taken from the Exif file of the photo. This
is the what you want as far as establishing the date and time the photo was
taken.
If you do not have the Date Picture taken column, right click on a column
header. A list will open, click on More at the bottom of the list and click
on Date Picture Taken on the opening list.

Yes, I know. And the technically correct definitions are as I gave in
my post.

"Date Time Original" and "Date Time Digitized" should be exactly the same
and this is what you have and this should correspond to the listing by
Explorer under Date Picture Taken.

As for the "Date Time", I don't know.

Anyone please?

 

[Yves]

Well, obviously, if you copy or move a file to a new folder, you get a new
Date created. You just created a new file on your computer! You want the old
Date Created carried over to the new file you just created? This is not
going to happen. It is indeed the same file, as far as the content, but it
is a new file created (or added) on your computer and as such it gets a new
Date Created when you copy the file to a new or different folder.
What is it that you want?
The Date Picture Taken?
The Date Picture Taken is not going to change, regardless of what you do.
Edit the file or copy it or move it to a new folder, but every time you copy
or move a file to a new folder you get a new Date Created and every time you
edit the file you get a new Date Modified but not a new Date Picture Taken.

 

[David Candy]

Moves don't change the create date as there is no new file.

 

[David Candy]

http://www.google.com.au/search?num=100&hl=en&safe=off&q=exif+specification&spell=1

DateTimeOriginal

The date and time when the original image data was generated. For a DSC the date and time the picture was taken

are recorded. The format is "YYYY:MMD HH:MM:SS" with time shown in 24-hour format, and the date and time

separated by one blank character [20.H]. When the date and time are unknown, all the character spaces except

colons (":") may be filled with blank characters, or else the Interoperability field may be filled with blank characters.

The character string length is 20 bytes including NULL for termination. When the field is left blank, it is treated as

unknown.

Tag = 36867 (9003.H)

Type = ASCII

Count = 20

Default = none

DateTimeDigitized

The date and time when the image was stored as digital data. If, for example, an image was captured by DSC and at the same

time the file was recorded, then the DateTimeOriginal and DateTimeDigitized will have the same contents. The format is

"YYYY:MMD HH:MM:SS" with time shown in 24-hour format, and the date and time separated by one blank character [20.H].

When the date and time are unknown, all the character spaces except colons (":") may be filled with blank characters, or else

the Interoperability field may be filled with blank characters. The character string length is 20 bytes including NULL for

termination. When the field is left blank, it is treated as unknown.

Tag = 36868 (9004.H)

Type = ASCII

Count = 20

Default = none


The other date is a last modified and is called "File change date and time". The first two dates are from an optional extra level of detail.

 

[Terry Pinnell]

http://www.google.com.au/search?num=100&hl=en&safe=off&q=exif+specification&spell=1

DateTimeOriginal

The date and time when the original image data was generated. For a DSC the date and time the picture was taken

are recorded. The format is "YYYY:MMD HH:MM:SS" with time shown in 24-hour format, and the date and time

<snip>

Thanks, appreciate your detailed reply. (BTW, there's something odd
about its formatting. As seen here, it appears to be in pairs of
lines, with a blank line between, sometimes splitting in middle of
sentences.)

I had studied the EXIF definitions before posting, from here:
http://www.exif.org/dcf.PDF

I seem to be observing data values at odds with those definitions.

I've now stepped through another example, from a photo taken myself
today.

Step 1. Ensured Sony Cybershot DSC-1 camera Clock settings showed
correct date and time.

Step 2. Took photo on 11th Oct 2005 at 07:27 by my digital watch

Step 3. Connected camera via USB to PC and displayed the contents of
file DCS0001.JPG in situ.

Data displayed at this stage by various programs
================================================
EXIF (various sources, e.g. IrfanView)
DateTime 2005:10:11 07:27:53
DateTimeOriginal 2005:10:11 07:27:53
DateTimeDigitized 2005:10:11 07:27:53

It might be useful to copy here from my previous post:
EXIF DEFINITIONS
'DateTimeOriginal' = "Date and time when an image was shot."
'DateTime' = "Date and time of file updating, like a file time stamp."
'DateTimeDigitized' = "Date and time when digital data was created."

I'm going to ignore the latter from now on, as I see how it *might* be
different to 'DateTimeOriginal' in rare cases, but never for a
digicam.

EXPLORER
Date Picture Taken 11/10/2005 07:27
Date Created 11/10/2005 07:27
Date Modified 11/10/2005 07:27

That's the familiar equality I'm use to seeing at this stage. However,
as I'll show later, it doesn't last indefinitely, despite many
apparently believing otherwise.

IRFANVIEW
File date/time: 11/10/2005 07:27:52

Step 4. Moved file from camera to PC via USB
Step 5. Cropped it once in IrfanView, at about 07:50.

EXPLORER
Date Picture Taken 11/10/2005 07:27
Date Created 11/10/2005 07:27
Date Modified 11/10/2005 07:27
Date Accessed 11/10/2005 07:50

Question 1: Why no change to Modified after cropping? (The definition
of EXIF seems to be clear it should change.)

Question 2: How is Date Accessed defined? (It plainly doesn't mean
what I think of as 'accessed'. It hasn't changed throughout the day,
despite being viewed in Explorer many times and also accessing its
Properties. It almost looks as if Explorer regards 'Accessed' as what
I mean by Modified.)

PAINTSHOP PRO 8
Date and time Tuesday, October 11, 2005 07:27:53 AM
Original date and time Tuesday, October 11, 2005 07:27:53 AM

Question 3: Presumably 'Date and time' here = EXIF DateTime ?

IRFANVIEW
DateTime 2005:10:11 07:27:53
DateTimeOriginal 2005:10:11 07:27:53
DateTimeDigitized 2005:10:11 07:27:53

Question 4: Is that extra 1 sec a consistent difference, arising from
the download to PC?

EXIFER
Date 11/10/2005 07:27:52
Date taken (EXIF/Image) 11/10/2005 07:27:53
Date modified Tue 11 October 2005 07:27:53

Question 5: Presumably 'Date' here = EXIF DateTime ?

Step 6. Cropped file again in IrfanView, at 20:44

EXPLORER
Date Picture Taken 11/10/2005 07:27
Date Created 11/10/2005 07:27
Date Modified 11/10/2005 07:27
Date Accessed 11/10/2005 07:50

Question 6: Why have neither Modified *nor* Accessed changed? (I'd
have expected both to now have a time stamp of 20:44.)

Step 7. Cropped file again in PSP8, at 20:48

EXPLORER
Date Picture Taken 11/10/2005 07:27
Date Created 11/10/2005 07:27
Date Modified 11/10/2005 07:27
Date Accessed 11/10/2005 20:48

Question 7: Why does PSP8 change Accessed and not also Modified?

Question 8: Why does PSP8 change Accessed but IrfanView didn't do so
this time, yet did so this morning?

Step 8: Moved file to a new folder

EXPLORER
Date Picture Taken 11/10/2005 07:27
Date Created 11/10/2005 07:27
Date Modified 11/10/2005 20:48
Date Accessed 11/10/2005 20:48

Question 9: Why does it apparently take a change of folder to get
Modified to reflect an earlier modification?

 

[David Candy]

You are talking about three (or four) different and unrelated property sets. Windows Times, EXIF, and Windows properties (some come from OLE Property sets).

Create/Modified/Last Access are part of the file system. There are different rules depending on underlying file system (Fat, like cameras use, is stored in local time an NTFS in UTC (atomic version of GMT). Last access date has different granularities - I do believe on one file system it's resolution is 24 hrs.

lpCreationTime
[out] Pointer to a FILETIME structure to receive the date and time the file was created. This parameter can be NULL if the application does not require this information.
lpLastAccessTime
[out] Pointer to a FILETIME structure to receive the date and time the file was last accessed. The last access time includes the last time the file was written to, read from, or, in the case of executable files, run. This parameter can be NULL if the application does not require this information.
lpLastWriteTime
[out] Pointer to a FILETIME structure to receive the date and time the file was last written to. This parameter can be NULL if the application does not require this information.
Note Not all file systems can record creation and last access time and not all file systems record them in the same manner. For example, on Windows NT FAT, create time has a resolution of 10 milliseconds, write time has a resolution of 2 seconds, and access time has a resolution of 1 day (really, the access date). On NTFS, access time has a resolution of 1 hour. Therefore, GetFileTime may not return the same file time information set using the SetFileTime function. Furthermore, FAT records times on disk in local time. However, NTFS records times on disk in UTC. For more information, see File Times.

Exif. Windows supports Exif files natively but it is meant for programmers to include exif features in their programs.

Windows Properties. The docs haven't been updated for years. The precede Date Picture Taken On. I guess it's reading this one thing from exif data. Most properties are OLE document properties (like in Word) or are specific to a name space extension (like revelence in Search or Date Deleted in Recycle Bin).

 

[Guest]

I've read thru each POST and the use of a CELL Phone as a Photo-File seems
less than Great..I would assume that a Numbered File might go a differant
route than mere PC-CD or PRINT File..so some action in a FAX-modem might need
some info that you just haven't experianced yet..ALSO...Time&Date need to be
SET by the user...some have an AUTO Set for TIME...what's the story
there..but I would quess some FAX-modem will handle your file.