The acronym JPEG (Joint Photographic Expert Group comes from the meeting held in 1982 of a group of photographic experts, whose main concern was to work on the ways to transmit information (still or animated images). In 1986, the ITU-T developed compression methods intended for fax sending. These two groups joined to create a joint photographic experts group (JPEG).
Unlike LZW compression, JPEG compression is a lossy, , which affords it one of the best compression ratios, despite the slight loss of quality (20: 1 with 25:1 without any significant loss of quality).
This compression method is much more effective for photographic images (comprising many different colored pixels) than on geometrical images (unlike LZW compression) because the nuance differences due to compression are very visible in the latter.
The stages of JPEG compression are the following:
File formats that save a flow coded in JPEG are actually called JFIF (JPEG File Interchange Format), but the term is usually deformed into “JPEG file".
It should be noted that there is a lossless form of JPEG coding. Although little used by the data-processing community in general, it is used especially for the transmission of medical images in order to avoid confusing artefacts (purely dependent on the image and its digitalization) with real pathological signs. Compression is thus much less effective (only factor 2).