This article is about a format for storing metadata in image files. For information about filename and directory structures of digital cameras, see Design rule for Camera File system. Design rule for Camera File system (DCF is a JEITA specification (number CP-3461 which defines a File format and File system for Digital cameras

the Exif Print Logo

Exchangeable image file format (Exif) is a specification for the image file format used by digital cameras. An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually A file format is a particular way to encode information for storage in a Computer file. Many compact digital still cameras can record Sound and moving Video as well as still Photograph. The specification uses the existing JPEG, TIFF Rev. 6. 0, and RIFF WAV file formats, with the addition of specific metadata tags. WAV (or WAVE) short for Waveform Audio format, is a Microsoft and IBM Audio file format standard for storing an audio bitstream on Metadata ( meta data, or sometimes metainformation) is "data about data" of any sort in any media It is not supported in JPEG 2000, PNG, or GIF. JPEG 2000 is a Wavelet -based Image compression standard It was created by the Joint Photographic Experts Group committee in the year 2000 with the intention Portable Network Graphics ( PNG) is a bitmapped image format that employs Lossless data compression.

Background

Exif was created by the Japan Electronic Industries Development Association (JEIDA). The was an industry research development and standards body for electronics in Japan Version 2. 1 of the specification is dated June 12, 1998, and the latest, version 2. Events 1381 - Peasants' Revolt: in England, rebels arrive at Blackheath. Year 1998 ( MCMXCVIII) was a Common year starting on Thursday (link will display full 1998 Gregorian calendar) 2 dated April 2002, is also known as Exif Print. Though the specification is not currently maintained by any industry or standards organisation, its use by camera manufacturers is nearly universal. Standardization (or standardisation) is the process of developing and agreeing upon technical standards.

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

• 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 ISO speed information. In Photography, shutter speed is the length of time a shutter is The focal length of an optical system is a measure of how strongly it converges (focuses or diverges (diffuses Light. In Photography, the metering mode refers to the way in which a Camera determines the exposure. Film speed is the measure of a photographic film's sensitivity to Light.
• A thumbnail for previewing the picture on the camera's LCD screen, in file managers, or in photo manipulation software. Thumbnails are reduced-size versions of Pictures used to help in recognizing and organizing them serving the same role for images as a normal text index does for
• Descriptions and copyright information.

Technical

The Exif tag structure is taken from that of TIFF files. On several image specific properties, there is a large overlap between the tags defined in the TIFF, Exif, TIFF/EP and DCF standards. " Tag Image File Format / Electronic Photography " (TIFF/EP is a Digital image File format standard – ISO 12234-2 titled Design rule for Camera File system (DCF is a JEITA specification (number CP-3461 which defines a File format and File system for Digital cameras For descriptive metadata, there is an overlap between Exif and IPTC Information Interchange Model info, which also can be embedded in a JPEG file. The Information Interchange Model (IIM is a file structure and set of Metadata attributes that can be applied to text Images and other media types

When Exif is employed for JPEG files, the Exif data is stored in one of JPEG's defined utility Application Segments, the APP1 (segment marker 0xFFE1), which in effect holds an entire TIFF file within. When Exif is employed in TIFF files (also when used as "an embedded TIFF file" mentioned earlier), the TIFF Private Tag 0x8769 defines a sub-Image File Directory (IFD) that holds the Exif specified TIFF Tags. In addition, Exif also defines a GPS sub-IFD using the TIFF Private Tag 0x8825, obviously holding location information, and a "Interoperability IFD" specified within the Exif sub-IFD, using the Exif tag 0xA005.

Geolocation

The Exif format has standard tags for location information. Currently, only very few cameras, such as the Ricoh 500SE or some higher-end mobile phones, have a built-in GPS receiver and store the location information in the Exif header when the picture is taken. ( or Ricoh, is a Japanese company that was established on 6 February 1936 as Riken Kankoshi Co For other cameras, such as Nikon D300 or Fujifilm S5Pro, a seperate GPS receiver that fits into the flash connector is available. Recorded GPS data can also be added to any digital photograph on a computer, either by correlating the time stamps of the photographs with a GPS record from a hand-held GPS receiver or manually using a map or mapping software, e. A GPS tracking unit is a device that uses the Global Positioning System to determine the precise location of a vehicle person or other asset to which it is attached and g. Geoseeker. Photo sharing communities like locr or Flickr equally allow their users to upload geotagged pictures or to add geolocation information online. Flickr is an image and video hosting Website, Web services suite and Online community platform The process of adding geographic information to a photograph is known as geocoding. A geocoded photograph is a Photograph which is associated with a geographical location

Program support

Exif data is embedded within the image file itself. While many recent image manipulation programs recognize and preserve Exif data when writing to a modified image, this is not the case for most older programs. In Computer graphics, graphics software or image editing software is a program or collection of programs that enable a person to manipulate visual images Many image gallery programs also recognise Exif data and optionally display it alongside the images.

Problems

Apart from not being a maintained standard, the Exif format has a number of drawbacks, mostly relating to its use of legacy file structures.

• The derivation of Exif from the TIFF file structure using offset pointers in the files means that data can be spread anywhere within a file, which means that software is likely to corrupt any pointers or corresponding data that it doesn't decode/encode. This is the reason most image editors damage or remove the Exif metadata to some extent upon saving.

• The standard defines a MakerNote tag, which allows camera manufacturers to place any custom format metadata in the file. This is used increasingly by camera manufacturers to store a myriad of camera settings not listed in the Exif standard, such as shooting modes, post-processing settings, serial number, focusing modes, etc. As this tag format is proprietary and manufacturer-specific, it can be prohibitively difficult to retrieve this information from an image (or properly preserve it when rewriting an image). Some manufacturers encrypt portions of the information; for example, Nikon encrypts the detailed lens data in their newer MakerNote data versions. ^[1]

• The standard only allows TIFF or JPEG files — there is no provision for a "raw" file type which would be a direct data dump from the sensor device. This has caused camera manufacturers to invent many proprietary, incompatible "raw" file formats. To solve this problem, Adobe developed the DNG format (a TIFF-based raw file format), in hopes that manufacturers would standardize on a single, raw file format. In Digital photography, the Digital Negative ( DNG) File format is a Royalty free RAW image format designed by Adobe Systems

• The Exif standard specifically states that color depth is always 24 bits. ^[2] However, many modern cameras, such as the Nikon D70 which captures 36 bits of color per pixel, can capture significantly more. The Nikon D70 is a digital single-lens reflex Camera model In Spring 2004 Nikon introduced it at the 2004 PMA Annual Convention and Trade Show Since Exif/DCF files cannot represent this color depth, many manufacturers have developed proprietary, non-compatible RAW image formats. A raw image file contains minimally processed data from the image sensor of a Digital camera or Image scanner.
• Most digital cameras can also capture video — the Exif standard has no provision for video files.
• Exif is very often used in images created by scanners, however the standard makes no provisions for any scanner specific information.
• Photo manipulation software sometimes fails to update the embedded thumbnail after an editing operation, possibly causing the user to inadvertently publish compromising information. ^[3]

• Exif metadata is restricted in size to 64 kB in JPEG images because according to the specification this information must be contained within a single JPEG APP1 segment. Although the FlashPix extensions allow information to span multiple JPEG APP2 segments, these extensions are not commonly used. This has prompted some camera manufacturers to develop non-standard techniques for storing the large preview images used by some digital cameras for LCD review. These non-standard extensions are commonly lost if a user re-saves the image using image editor software, possibly rendering the image incompatible with the original camera that created it.
• There is no way to record time-zone information along with the time, thus rendering the stored time ambiguous.
• There is no field to record readouts of a camera's accelerometers or inertial navigation system. An accelerometer is a device for measuring Acceleration and gravity induced reaction forces An Inertial Navigation System (INS is a Navigation aid that uses a Computer and motion sensors to continuously track the position orientation and Velocity Such data could help to establish the relationship between the image sensor’s XYZ coordinate system and the gravity vector (i. e. , which way is down in this image). It could also establish relative camera positions or orientations in a sequence of photos.

Competitors

Extensible Metadata Platform (XMP) was created by Adobe Systems as a better metadata format for photography and image processing. The Adobe Extensible Metadata Platform ( XMP) is a standard for processing and storing standardized and proprietary metadata created by Adobe Systems Inc Adobe Systems Incorporated (pronounced a-DOE-bee əˈdoʊbiː ( is an American Computer software company headquartered in San Jose California However, it is generally unsupported in cameras.

Viewing and editing Exif data

Eye of Gnome screenshot showing Exif data of an image on a Linux system

In Windows XP and later Microsoft operating systems, 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. Eye of GNOME is the official Image viewer for the GNOME desktop environment A screenshot, screen capture, or screen dump is an Image taken by the Computer to record the visible items displayed on the monitor Image file formats are standardized means of organising and storing images However, this can damage certain Exif headers if changes are applied. ^[4] Other Windows software like Exif Harvester may be more reliable.

On Mac OS X 10. Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently 4 and above, this information may be viewed in the Finder by doing Get Info on a file and expanding the More Info section.

On Unix systems using the GNOME desktop environment, a subset of Exif data can be seen by right clicking the file in the Nautilus file manager and selecting properties. Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer A gnome is a Mythical creature characterized by its extremely small size and subterranean lifestyle In graphical computing a desktop environment ( DE) commonly refers to a style of Graphical user interface (GUI that is based on the Desktop metaphor which Nautilus is the official File manager for the GNOME desktop The name is a play on words evoking the shell of a Nautilus to represent an In KDE, it can be seen by right clicking, selecting "Properties" and then "Meta info". KDE ( K Desktop Environment) (ˌkeɪdiːˈiː is a Free software project which aims to be a powerful system for an easy-to-use Desktop environment. Most Unix image viewers give the full set of Exif data.

There are many software tools available which allow both viewing and editing of Exif data. The Opanda IExif Viewer[1] is a free stand-alone application, and also a plug-in for MSIE and Firefox on Windows platforms, that allows examination of detailed Exif data online by right clicking on an image. ^[5] FxIF and Exif Viewer are multi-platform extensions for Firefox that display Exif data in the image properties dialog. This feature is native in the web browser, Opera under image properties. Opera is a Web browser and Internet suite developed by the Opera Software company

Retrieval of detailed Exif data not usually displayed by other programs can be accomplished using ExifTool which runs in Perl, and is available for all platforms. ExifTool is Free software used for reading writing and manipulating Metadata. NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below

For AmigaOS/MorphOS 'SView5' covers a lot of the previously mentioned functionality.

Example

Konqueror screenshot showing Exif data

The following table shows Exif data for a photo made with a typical digital camera. Konqueror is a Web browser, File manager and File viewer designed as a core part of the K Desktop Environment. Notice that authorship and copyright information is generally not provided in the camera's output, so it must be filled in during later stages of processing.

FlashPix extensions

The Exif specification also includes a description of FPXR (FlashPix-Ready) information which may be stored in APP2 of JPEG images using a structure similar to that of a FlashPix file. FlashPix is a bitmapped Computer graphics file format where the image is saved in more than one resolution. ^[6] These FlashPix extensions allow meta information to be preserved when converting between FPXR JPEG images and FlashPix images. FPXR information may be found in images from some models of digital cameras by Kodak and Hewlett-Packard. Eastman Kodak Company ( is an American multinational Public company which produces imaging and photographic materials and equipment Below is an example of the FPXR information found in a JPEG image from a Kodak EasyShare V570 digital camera:

Exif audio files

The Exif specification describes the RIFF file format used for WAV audio files, and defines a number of tags for storing meta information such as artist, copyright, creation date, and more in these files. WAV (or WAVE) short for Waveform Audio format, is a Microsoft and IBM Audio file format standard for storing an audio bitstream on ^[7] The following table gives an example of Exif information found in a WAV file written by the Pentax Optio WP digital camera:

MakerNote data

The 'MakerNote' tag contains image information normally in a proprietary binary format. Some of these manufacture specific formats have been decoded:

• OZHiker: Agfa, Canon, Casio, Epson, Fujifilm, Konica/Minolta, Kyocera/Contax, Nikon, Olympus, Panasonic, Pentax/Asahi, Ricoh, Sony ^[8]

• Kamisaka: Canon, Casio, FujiFilm, ISL, KDDI, Konica/Minolta, Mamiya, Nikon, Panasonic, Pentax, Ricoh, Sigma, Sony, WWL^[9]

• X3F Info: Sigma/Foveon^[10]

• ExifTool: Canon, Casio, FujiFilm, JVC/Victor, Kodak, Leaf, Konica-Minolta, Nikon, Olympus/Epson, Panasonic/Leica, Pentax/Asahi, Ricoh, Sanyo, Sigma/Foveon, Sony^[11]

• Olypedia: Olympus^[12]

See also

• Digital photography
• Image processing
• Steganography

• Image file formats
• Tag Image File Format / Electronic Photography (TIFF/EP)
• Geocoded photo
• eXtensible Metadata Platform (XMP)
• Point of interest

• Design rule for Camera File system (DCF)
• International Press Telecommunications Council (IPTC)

References

Technical Standardization Committee on AV & IT Storage Systems and Equipment (April 2002). "Exchangeable Image File Format for Digital Still Cameras (JEITA CP-3451)" (. PDF). Version 2. 2. . Japan Electronics and Information Technology Industries Association Retrieved on 2008-01-28. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1077 - Walk to Canossa: The Excommunication of Henry IV Holy Roman Emperor is lifted

External links

• Exif 2. 2 Specification as PDF file or as HTML
• Exif Print info on Cipa site
• Exif in the TIFF Tags Directory