JPEG (Joint Photographic Experts Group) refers to a standards organization, a method of file compression.File Interchange Format (JFIF) is a development of C-Cube Microsystems for the purpose of storing JPEG-encoded data. JFIF is designed to allow files containing JPEG-encoded data streams to be exchanged between otherwise incompatible systems and applications.
A JFIF file is basically a JPEG data stream with a few restrictions and an identfying marker. In order to understand the JFIF format, you'll need to understand JPEG
Both JPEG and JFIF data are byte streams, always storing 16-bit word values in big-endian format. JPEG data in general is stored as a stream of blocks, and each block is identified by a marker value.
The first two bytes of every JPEG stream are the Start Of Image (SOI) marker values FFh D8h. In a JFIF-compliant file there is a JFIF APP0 (Application) marker, immediately following the SOI, which consists of the marker code values FFh E0h and the characters JFIF in the marker data, as described in the next section. In addition to the JFIF marker segment, there may be one or more optional JFIF extension marker segments, followed by the actual image data.
The first two bytes of every JPEG stream are the Start Of Image (SOI) marker values FFh D8h. In a JFIF-compliant file there is a JFIF APP0 (Application) marker, immediately following the SOI, which consists of the marker code values FFh E0h and the characters JFIF in the marker data, as described in the next section. In addition to the JFIF marker segment, there may be one or more optional JFIF extension marker segments, followed by the actual image data.
SOI is the start of image marker and always contains the marker code values FFh D8h.
APP0 is the Application marker and always contains the marker code values FFh E0h
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