4 messages in com.googlegroups.google-picasa-data-apiRe: <exif:time> messes up time zone(s)?
FromSent OnAttachments
John McLaughlin01 Dec 2007 22:13 
John McLaughlin04 Dec 2007 12:40 
Ryan Boyd (Google)04 Dec 2007 12:57 
John McLaughlin04 Dec 2007 23:26 
Subject:Re: <exif:time> messes up time zone(s)?
From:John McLaughlin (logh@gmail.com)
Date:12/04/2007 11:26:02 PM
List:com.googlegroups.google-picasa-data-api

Hi Ryan,

Thanks for the response -- I agree the exif spec ignores time zones -- what's unfortunate is that the way the exif entry comes back from Picassa it adds a time zone so it's usually wrong.

I've got a work around for my needs to basically get back the exif time by calculating it in GMT (without the time zone) -- I guess if I was king of the world I'd say that the exif tags should return date/ time without any assumptions of time zones (e.g. maybe just return the raw, ascii string out of the exif data) -- Perhaps something could be added to make life a bit easier for parsing the feeds?

-John

On Dec 4, 12:58 pm, "Ryan Boyd (Google)" <api.@google.com> wrote:

Hi John,

I've been trying to find an answer to this, but it appears that the Exif specification pretty much ignores the timezone for the DateTime tag. For some of the other timestamp information (related to GPS info), it does specify that the time should be in UTC.

Since it's not known what the time included in the exif represents, it's difficult to do any calculation on it. We could possibly use the GPS information, but we still likely won't know the real accuracy (and very few people have GPS info). If we do just use the geotagged location, it's unlikely that many people change the time on their cameras every time they cross a timezone.

If you have any suggestions, we'd love to hear them.

Here's a pointer to the Exif spec if you don't have
it:http://www.exif.org/specifications.html

Cheers, -Ryan

On Dec 4, 2007 12:40 PM, John McLaughlin <logh@gmail.com> wrote:

Ok, so not a mass of responses.

My current plan is to convert it back to a timestamp but ignore the time zone error (e.g. assume the user is living in GMT when I do the conversation)

-John

On Dec 1, 10:14 pm, John McLaughlin <logh@gmail.com> wrote:

Hi All,

I came across an odd problem. the way Picassa returns the exif time is in milliseconds since 1970 but it appears that Picassa is assuming the picture was taken in GMT time -- the actual exif data is stored in the camera in normal ascii (no mention of time zone) so when you view the original and the picassa date stamp they are off by your timezone.

what this means is when get the photo feed the <exif:time> will be wrong for about 6 Billion people as most of us don't live in GMT (for those of you who do live in Greenwich you can ignore this post as everything works great :-))

I tried to geotag the photo but that doesn't seem to do it either -- The photo timestamp stubbornly stll thinks it's in Greenwich (even though I've said "Hey, you are actually taken in California!)

But perhaps I'm missing something -- is there some clever way to get back the original date? (or perhaps I'm not understanding how the API works?)