inkjet printer An inkjet printer creates images out of
millions of nearly invisible colored dots. The dots are cre-
ated by squirting ink through extremely small nozzles. See
alsodithering.
JPEG (Joint Photographic Experts Group)A software
procedure that compresses files. JPEG is a “lossy” compres-
sion algorithm that degrades image quality, although the
apparent effect is small unless the image is highly com-
pressed.
JPEG 2000 A revision of the JPEG image compression
standard. Along with slightly improved image quality, new
features permit images to be viewed with greater color
accuracy and allow encoded copyright protection, as well as
embedded keywords to assist Internet searches.
kilobyte (KB) A measure of computer memory, disk stor-
age, or file size consisting of approximately one thousand
bytes. The actual value is 1,024 bytes.
laser printer A computer printer that uses laser copier
technology to print from computer data. Printing is much
faster than with inkjet and dye sublimation printers, but
image quality is often compromised by banding.
layer A software feature that permits an image to con-
tain a number of separate images, viewed as though they
are stacked upon each another. Some software allows spe-
cialized layers such as adjustment layers, which contain no
visible images but contain commands that change the
tones and colors of the layers below, or type layers, which
contain editable letters and numbers.
LCD panel (liquid crystal diode) Many digital cam-
eras have illuminated LCD screens that are used as
viewfinders. They also permit the editing of pictures after
they have been captured.
lossless compression A file compression technology
that reduces the size of files in ways that result in the origi-
nal file being intact after decompression. There is no loss of
the original data. TIFF compression is lossless.
lossy compression A file compression technology that
reduces the size of files in ways that result in permanent
changes to the original file after decompression. Depending
on the degree of compression used, the image may exhibit
noticeable artifacts. JPEG compression is lossy.
marquee An outline of moving dashes that appears on
the monitor to show the boundaries of selected areas within
an image. See alsoselection.
mask An image-editing tool used to limit the effects of
image editing to certain areas of the image. Masks appear350 ABSOLUTE BEGINNER’S GUIDE TODIGITAL PHOTOGRAPHYon the monitor as overlays of color. Unlike a selection,
masks can be stored and can be edited for later reuse.
Masks are stored in the channels palette of Adobe
Photoshop.
megabyte (MB) A measure of computer memory, disk
storage, or file size consisting of approximately one million
bytes. The actual value is 1,048,576 bytes.
megapixel camera A digital camera whose CCD chip
has over one million individual sensors. Each sensor usu-
ally creates one pixel in the camera’s images.
metadata Data about data. EXIF information included
in digital camera images is one example. The EXIF stan-
dard states what information is stored in a JPEG image and
in what order. This data describes the image itself.
modem (modulator/demodulator) A device that con-
verts outgoing digital data into analog signals for transmis-
sion over telephone lines, and digitizes incoming analog
signals.
network A group of computers connected electronically
so they can exchange data and share peripheral devices,
such as printers and modems.
palette On a computer monitor, a software component
that appears as a box containing icons of tools and controls
that modify the way tools operate (options). A command
center for image-editing tools.
PhotoCD and PictureCD Kodak scanning services
available from many photography stores and mini-labs.
PhotoCD Master scans offer high-quality images from
35mm film with resolutions up to 3072×2048 pixels. Less
expensive PictureCD scans of 1536×1024 pixels are saved as
JPEG files.
pixel (picture element) The smallest visible component
of a digitized image. The basic dot that contains a single
color.
plug-in A small, specialized software program that is
opened and operated by image-editing software, and closed
when its task is finished. For example, scanner software is
used to capture and import images, and filters are used to
modify the image. Plug-ins may be manufactured by com-
panies unconnected with the manufacturer of the imaging
software.
ppi (pixels per inch) Seedpi.
quantization coefficient A variable number related to
the Quality setting used when a JPEG file is saved. The
quantization coefficient is used with JPEG quantization
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