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Exchangeable image file format (Exif) is a specification for the image file format used by digital cameras. It was written by the Japan Electronic Industry Development Association (JEIDA).
| · | The meta data tags defined in the Exif standard cover a broad spectrum including:
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| · | Date and time information. Digital cameras will record the current date and time and save this in the meta data.
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| · | 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.
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| · | 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.
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| · | 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.
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IPTC stands for “International Press Telecommunications Council”. IPTC information may be embedded in JPG, TIFF, PNG, MIFF, PS, PDF, PSD and DNG images.
| · | The IPTC specification dictates a length for ASCII (string or digits) values. These lengths are given in square brackets after the Writable format name. For tags where a range of lengths is allowed, the minimum and maximum lengths are separated by a comma within the brackets.
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| · | IPTC strings are not null terminated.
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| · | IPTC information is separated into different records, each of which has its own set of tags.
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