Exchangeable image file format

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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 existing file formats such as JPEG, TIFF Rev. 6.0, and RIFF WAVE audio file format, 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 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.
Location information, which could come from a GPS receiver connected to the camera. As of 2004 only a few cameras support this, though. Some people therefore use a normal receiver to track their movements, and then post-process the images by matching the timestamps in the images with the log from the receiver and can so add the missing information to images.
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.

1 Program support
2 Capitalization
3 Status
4 Viewing Exif
5 Example
6 See also
7 External links
- 7.1 References

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Program support

Exif data is embedded within the image file itself. While many recent image manipulation programs recognize Exif data and will maintain it when writing to a modified image, this is not the case for most older programs.

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Capitalization

While Exif is an acronym, and would normally be uppercased, the official specification defines it as "Exif".

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Status

The Exif specification is currently unmaintained because there is no public entity or people officially behind Exif.

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Viewing Exif

In Windows XP, A subset of the Exif information may be viewed by right clicking on an image file and clicking properties; from the properties dialog click the Summary tab. However, this may damage the Exif header.

On Mac OS X 10.4 and above, this information may be viewed in the Finder by doing Get Info on a file and expanding the More Info section. Image:Eog EXIF.png On Linux/Gnome System Eye of Gnome (eog) tool can be used for viewing EXIF data.

There are many software tools available which allow both viewing and editing of Exif data.

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Example

The following table shows Exif data for a photo made with a typical digital camera. Notice that authorship and copyright information is not provided in the camera's output, so it must be filled in during later stages of processing.

Tag	Value
Manufacturer	CASIO
Model	QV-4000
Orientation	top - left
Software	Ver1.01
Date and Time	2003:08:11 16:45:32
YCbCr Positioning	centered
Compression	JPEG compression
x-Resolution	72.00
y-Resolution	72.00
Resolution Unit	Inch
Exposure Time	1/659 sec.
FNumber	f/4.0
ExposureProgram	Normal program
Exif Version	Exif Version 2.1
Date and Time (original)	2003:08:11 16:45:32
Date and Time (digitized)	2003:08:11 16:45:32
ComponentsConfiguration	Y Cb Cr -
Compressed Bits per Pixel	4.01
Exposure Bias	0.0
MaxApertureValue	2.00
Metering Mode	Pattern
Flash	Flash did not fire.
Focal Length	20.1 mm
Maker Note	432 bytes unknown data
FlashPixVersion	FlashPix Version 1.0
Color Space	sRGB
PixelXDimension	2240
PixelYDimension	1680
File Source	DSC
InteroperabilityIndex	R98
InteroperabilityVersion	(null)