Page 60 - Payout Magazine Online Volume 8.9

PEG stands for Joint Photographic Experts Group. It
Jis an initiative that has been creating still image coding
progreSSive vS. standards for some time. Origins trace back to the 1980’s.
However, the JPEG format was officially created in 1992.
Its filename extensions are .jpeg and .jpg. JPEG works
BaSeline JpegS: best on realistic images with smooth variations. This is
why it works best on photographs. Over 70 percent of
websites currently uses JPEG.
decreaSe your JPEG is the dominant format for still images. Its focus

is on open source software. Specifically, the joint initiative
page load timeS creates a reference implementation for the ISO/IEC 10918
standard. JPEG.org lists 7 parts to the implementation:

� Requirements and guidelines

� Compliance testing

� Extensions

� Registration authorities

� File interchange format (jfif)

� Application to printing systems

� Reference software

These 7 parts serve to guide the coding system,
compliance, and registration. Changing formats,
extensions, and printing are also determined by the
committee.

Progressive vs. Baseline JPEG Images

There are two types of JPEG image formats: Baseline
and Progressive. A Baseline JPEG image will begin to
display as data becomes available. This will occur line by
line. Baseline JPEG images display from top to bottom
in web browsers. A Progressive JPEG image begins as
a low quality or blurry full size image. As the download
process continues, the image becomes clearer while
it progressively renders to a higher quality. The default
JPEG image format is Baseline. It is the more common
format.

Advantages of Each Type

Progressive rendering provides users with feedback
of the loading process. The progressive format has
practical applications. It can aid viewing choices during
slow Internet connection speeds. This is possible
because even with the initial low quality of a progressive
rendering, there is still a full sized image present on the
screen. Baseline images are entirely missing part of the

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