Exif

The Exchangeable image file format (Exif) is an image file format which adds lots of metadata to existing image formats, mainly JPEG.

To read the Date/Time tag do:

 exif --tag=0x132 filename.jpg       (reveals Date & Tag) 
 exif --tag=0x9003 filename.jpg      (reveals Date and Time (original))
 exif --tag=0x9004 filename.jpg      (reveals Date and Time (digitized))

To set the Date/Time tag:

 exif  --tag=0x132 --set-value="1975:01:01 12:01:01" --ifd=0 filename.jpg

For tools that extract Exif meta data look here - Document_Metadata_Extraction#Images

External Links

• exif.org
• Exif 2.2 specification
• Exif article in the Wikipedia.