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Exchangeable Image file Format (ExIF)
The Japanese Electronic Industry Development Association (JEIDA) created a standard for the storage of camera
and image metadata in JPEG and TIFF files. Most digital camera manufacturers have implemented this standard and
now store camera metadata along with the digital image. This metadata can potentially provide vital evidence to
investigators such as when the picture was taken, what camera was used in capturing the image and in some cases,
who took the image or where the image was captured.
In 1992, the first JPEG file format standard (JFIF) was defined to enable the interchange of JPEG bit streams
between a wide variety of applications and platforms. In conformity with the JPEG specification, JFIF added key
information to the file such as resolution and standardized color space, and provided for the addition of a
thumbnail image. In June, 1998, the JEIDA developed a new standard to allow camera manufacturers to embed
camera and image metadata into a JPEG file in conformity with the existing JPEG specification. This standard, called
the Exchangeable Image file Format (ExIF) enabled digital camera manufacturers to include information such as
camera make and model, camera settings, time, author, copyright and other information directly into the image file
so that the photographer would have a permanent record of this information preserved along with the image. By
early 2001, most camera manufacturers had implemented this capability into the camera they marketed worldwide.
This information can be extracted from the image and may provide vital clues and evidence to investigators.
Every JPEG file begins with “FFD8” which is defined as the SOI (Start of Image) Marker and ends with “FFD9”
which is the EOI (End of Image) marker. In between these two markers, the data is divided into several segments,
each of which is defined by a spe