ExifTool Forum

General => Metadata => Topic started by: oliver42 on February 05, 2018, 06:27:32 AM

Title: approximate date ?
Post by: oliver42 on February 05, 2018, 06:27:32 AM
If you use a modern camera, it will write the current date into the exif-portion of the image.

However: if you have digital images scanned from analog pictures, you often do not know the exact date of creation.

I really don't like to put 01.01.1970 on all the images that were taken in the year 1970.

Are there any ideas how to specify an approximate date or a possible range for the date ?
Title: Re: approximate date ?
Post by: Phil Harvey on February 05, 2018, 07:47:09 AM
See FAQ 5 (https://exiftool.org/faq.html#Q5).  As well, technically it is allowed, although not recommended, to leave EXIF date/time fields blank (filled with spaces).  To do this you must add the -n option when writing with ExifTool.

- Phil
Title: Re: approximate date ?
Post by: StarGeek on February 05, 2018, 11:46:27 AM
Quote from: Phil Harvey on February 05, 2018, 07:47:09 AM
As well, technically it is allowed, although not recommended, to leave EXIF date/time fields blank (filled with spaces).

Ah, so it's supposed to be something like "2018:02:05 __:__:__" (using underscores as place holders)?  I've been using just "2018:02:05" (truncated) in my exif timestamps where I don't know the exact time.  I'll have to go back and retest some programs, though I don't expect them to read this format either.

@oliver42, I also don't like the inaccuracy in using the lowest possible number as a place holder for unknown values.  While the XMP tags can hold partial dates, very few programs will use them and read them properly.

One thing I have seen done is putting partial timestamps in keywords.  That does allow for searching for files in photo  management programs. 
Title: Re: approximate date ?
Post by: Phil Harvey on February 05, 2018, 11:51:29 AM
Quote from: StarGeek on February 05, 2018, 11:46:27 AM
Ah, so it's supposed to be something like "2018:02:05 __:__:__"

Yes, this is what I meant.  But re-reading the EXIF spec, maybe I should have said "technically it is possible" instead of "technically it is allowed", because the spec seems to imply an all-or-nothing for the spaces:

The date and time of image creation. In this standard it is the date and time the file was changed. The format is "YYYY:MM:DD 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 (":") should be filled with blank characters, or else the Interoperability field should 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.

- Phil
Title: Re: approximate date ?
Post by: StarGeek on February 05, 2018, 12:21:38 PM
Well, to heck with it then.  I'm just going to keep on with my partials.  It may not work well with my DAM, but it makes me happy :D
Title: Re: approximate date ?
Post by: oliver42 on February 06, 2018, 01:44:07 PM
So that means, that tools like Adobe Lightroom are not able to interpret the blanks in the date string ?