Renaming based on date and time

Describe any features you would like to see in future versions of FastPictureViewer Professional.

Renaming based on date and time

Postby Cliff on Tue Jan 10, 2012 9:17 pm

I would like to rename an image file to the date and time it was taken, but there is a problem. This is the template I created.


It gives the following name to an nef file.


The date is correct and so are the minutes and seconds, but the hour is wrong. I'm very sure I didn't take the photo at 4am. Most likely I took it eight hours later at 120630. I should also point out that I'm in the US Pacific time zone (UTC-8). Am I wrong about this, or does something need to be fixed?

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Re: Renaming based on date and time

Postby Axel on Tue Jan 10, 2012 10:53 pm

There is no notion of time zone in EXIF metadata data and time information, unfortunately. Some cameras (like for example the D3) have some time zone setting but this only affects the time difference the camera will apply between its internal clock and the time written in the files. The file themselves (at least the documented EXIF data in them) don't have a time zone field, which opens the door for confusion when interpreting the time in application software.

The first thing you should do is make sure you are using the latest version of FastPictureViewer.

Next, compare the date/time you get with what's in the file, using some sort of EXIF viewer like ExifTool, Opanda iExif, or PhotoMe ( just to name three.

Also compare with what the program displays in its EXIF shooting data window (I-key).

You should probably use the "Utc" version of the date variables (like {DateTakenUtc}), which uses the data in the files as-is without modification. This is kind-of counter-intuitive but it is based on the idea that a camera might be set to UTC, and the variable would return that time irrespectively of the current time zone in effect.

The non-Utc variables (like {DateTaken}, that you used in the example below) also assume that the camera was set to UTC, and apply a time-zone change according to your current computer time zone. So if your camera was already set to local time, you can use the Utc-suffixed variables instead, which gives you the "raw" time found in EXIF.

All this sounds a little weird but all file timestamps are stored in UTC in your computer. When displaying a file time an application must convert the UTC time stamp, returned by the file system, to local time before displaying it. This is exactly what FPV does for EXIF times, i.e. it assumes that the time in the files is UTC, for a lack of better information, and converts it to local time for display.

To complicate matters even further, GPS-equipped cameras always write the GPS time in UTC in EXIF data, and with this field, as well as the file system file time & date fields like creation or modification, the original meaning of the variable names makes all its sense, Utc is UTC and non-Utc is local time, according to the computer time zone.

The next logical evolution of the EXIF standard would be to include a time offset field and that new cameras store the time as UTC like everyone else (using the ISO 8601 standard, like for example XMP, would be a good start). When that day comes the true meaning of FPV variable will come to light 8-)
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Re: Renaming based on date and time

Postby pszilard on Thu May 03, 2012 1:29 am

I wonder if with the Codepack exposing some data, one can use NameWiz to do this...
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