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Wrote a subsection on the specifications and ambiguities of time-related tags. |
→Time Tags: Added note about null terminator (otherwise people may wonder where the 7th character is) |
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The standard does not specify which particular event during the "taking" of a picture the time tags should describe. The standard is, in fact, ambiguous. The <code>DateTimeOriginal</code> tag is defined as "The date and time when the original image data was generated." For an exposure—say, 30 seconds—longer than the granularity of the timestamp (one second for the <code>DateTimeOriginal</code> tag), the tag's time could correspond to the beginning of the exposure, the end of the exposure, or some other time. This confusion is exacerbated for the subsecond tags, where the granularity (down to 1/10000th of a second in the examples in the standard) is shorter than many common exposure durations.
As noted above, tags to specify the previously-missing timezone information were added in Exif version 2.31. These are "OffsetTime", "OffsetTimeOriginal" and "OffsetTimeDigitized". They are formatted as seven ASCII characters (including the null terminator) denoting the hours and minutes of the offset, like <code>+01:00</code> or <code>-01:00</code>. The offset is "from UTC (the time difference from Universal Coordinated Time including daylight saving time) of the time of"<ref>{{cite web |url=http://www.cipa.jp/std/documents/e/DC-008-2012_E.pdf |title=Standard of the Camera & Imaging Products Association, CIPA DC-008-Translation-2012, Exchangeable image file format for digital still cameras: Exif Version 2.3 |access-date=2014-04-08 }}</ref> the matching tag.
==FlashPix extensions==
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