Exchangeable image file format

I happened to have a talk with my rommie about having some "meta tags" inside images/videos to enable faster searching in the net. I did disagree with him over the concept of just having some meta tags inside images to describe them, as he pointed out, it is(was) being used in html pages for better searching of pages. Then today, i came across this information on a standard file format used by digital camera manufacturers to embed information on images captured by their devices.

Exchangeable image file format

Exchangeable image file format (official abbreviation Exif, not EXIF) is a specification for the image file format used by digital cameras. It was created by the Japan Electronic Industry Development Association (JEIDA). The specification uses the existing JPEG, TIFF Rev. 6.0, and RIFF WAVE file formats, with the addition of specific metadata tags. It is not supported in JPEG 2000 or PNG.

Version 2.1 of the specification is dated June 12, 1998 and version 2.2 is dated April 2002.

The Exif tag structure is taken from that of TIFF files. There is a large overlap between the tags defined in the TIFF, Exif, TIFF/EP and DCF standards.

The metadata tags defined in the Exif standard cover a broad spectrum including:

* Date and time information. Digital cameras will record the current date and time and save this in the metadata.
* Camera settings. This includes static information such as the camera model and make, and information that varies with each image such as orientation, aperture, shutter speed, focal length, metering mode, and film speed information.
* A thumbnail for previewing the picture on the camera's LCD screen, in file managers or photo manipulation software.
* Descriptions and copyright information. Again this is something which is most often done when post-processing the images, as only high-end camera models let the user choose a text for these fields. (Although this feature is becoming more and more apparent even in lower end compact digital cameras).

Editing EXIF-fields

Tools

The Gnu Image Manipulation Program (GIMP) is the chief Free Software image manipulation program which can handle EXIF data via an EXIF viewer plugin.

There are also several command line tools that are for example helpful for batch editing EXIF meta data like jhead and ExifTool (Perl script), that can display and edit XMP, IPTC and EXIF and other metadata.

ExifTool runs on OS X, but requires a Perl interpreter (such as ActivePerl) to run on Windows.

Mapivi (open source) is a picture manager which is able to add, edit, search and remove image meta information as EXIF and IPTC.

Gimp, Mapivi and jhead are also available for Mac OSX and Windows.

Linux/Unix users

Many free software image programs like the digital camera management program DigiKam and the general purpose image viewer Gwenview (both KDE based) can handle EXIF as well.

MacOSX users

Apple's iPhoto can be used to edit title, date, time and keywords. The camera information can also be viewed.

JetPhoto can be used to add GPS data to a photoalbum. JetPhoto uses timestamp information to correlate tracking data from a GPS device with the timestamps on the photo. JetPhoto is freeware so there is no charge but it does not appear to be open source. Keywords, and titles can be edited but no other information.

Reveal can be used to view and edit EXIF summary and exposure data.

Windows users

Programs XnView (free for non-commercial use), Picasa (freeware) and IrfanView, (free of charge for private use) are able to edit IPTC fields such as captions, keywords, etc., but unluckily can only view most of EXIF fields. Else Exifer (postcardware) Konvertor (shareware) is capable as well editing and modifying the EXIF header.

For more information on this,
http://en.wikipedia.org/wiki/EXIF
see, no wonder why people call me a wiki fan :)