Page 172 - ITU Journal, ICT Discoveries, Volume 3, No. 1, June 2020 Special issue: The future of video and immersive media

ITU Journal: ICT Discoveries, Vol. 3(1), June 2020

The JPEG did not also target motion image applications because it was a disciplined standards group whose
limits of standardization were clearly defined by its parent SDOs. In CCITT, JPEG was responsible for
photographic still images, while CCITT SGXV was responsible for developing a video coding standard for an
ISDN videophone and later to other type of networks. In ISO/IEC JTC1/SC2 and later SC29, JPEG was also
responsible for photographic still images and then in 1988 the emerging MPEG became responsible for videos
on digital storage media (like compact discs in MPEG-1). MPEG-2 digital TV was not even on the horizon (that
came in the early 1990s).

Therefore, there is no standard that defines a single exact format that is universally recognized as a complete
specification for motion JPEG for use in all contexts. This raised compatibility concerns about file outputs from
different manufacturers. However, each particular file format usually has a standard on how M-JPEG is
encoded. For example, Microsoft documents their standard format to store M-JPEG in AVI files, Apple
documents how M-JPEG is stored in QuickTime files and IETF RFC 2435 [29] describes how M-JPEG is
implemented in an RTP stream.
According to Wikipedia [30],

“Motion JPEG (M-JPEG or MJPEG) is a video compression format in which each video frame or interlaced
field of a digital video sequence is compressed separately as a JPEG image. The JPEG still image compression
standard can be applied to video by compressing each frame of video as an independent still image and
then transmitting them in series. Video that has been coded this way is defined as a Motion JPEG.

M-JPEG is an intraframe-only compression scheme (compared with the more computationally intensive
technique of interframe prediction). Whereas modern interframe video formats, such as MPEG1, MPEG2
and H.264/MPEG-4 AVC, achieve real-world compression ratios of 1:50 or better, M-JPEG's lack of
interframe prediction limits its efficiency to 1:20 or lower, depending on the tolerance to spatial artifacting
in the compressed output. Because frames are compressed independently of one another, M-JPEG imposes
lower processing and memory requirements on hardware devices.
As a purely intraframe compression scheme, the image quality of M-JPEG is directly a function of each video
frame's static (spatial) complexity. Frames with large smooth transitions or monotone surfaces compress
well and are more likely to hold their original details with few visible compression artifacts. M-JPEG-
compressed video is also insensitive to motion complexity, i.e. variation over time. It is neither hindered by
highly random motion (such as the water-surface turbulence in a large waterfall), nor helped by the
absence of motion (such as static landscape shot by tripod), which are two opposite extremes commonly
used to test interframe video formats.
M-JPEG enjoys broad client support — most major web browsers and players provide native support, and
plug-ins are available for the rest. Minimal hardware is required because it is not computationally
intensive.”

Originally developed for multimedia PC applications, M-JPEG is now used by video-capture devices such as
digital cameras, Internet protocol (IP) cameras, and webcams, as well as by non-linear video editing systems.

So, a motion JPEG standard takes advantage of the toolbox nature of JPEG to achieve its functionalities, but
that needs to be extended for practical implementation.

It is surprising that M-JPEG is still used in several applications and systems today.

4.4 Exchangeable image file format
The use of JPEG-1 in digital photography is one of the most important applications today. In mobile phones
alone, there are about 4 billion photo-cameras. Today smart phones dominate the photo-camera market. Each
camera takes about 260 JPEG pictures per year, resulting in 1 trillion (1 000 000 million) JPEG photos each
year. Taking all images, including the analogue images that have been taken over the more than 150 years
since the invention of photography, the estimated total is 5,7 trillion pictures. JPEG pictures have practically
dominated all pictures taken worldwide since the introduction of the format (All stats are from Ahonen [31]).

With such a background, it may sound strange that although the JPEG committee saw that digital photography
would be a very important use case one day in the future, it did not see:

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