| Digital Imaging Terms
aliasing
When smooth lines and curves in a digital image are distorted due to low
resolution.
antialiasing, anti-aliasing
A software technique for reducing jagged lines and curves by using shades
of gray and color to smooth out the contrast between neighboring pixels.
While this technique may result in a loss of overall image clarity, it
greatly reduces the appearance of jaggies.
dithering
Adjusting the appearance of colors and
shades in an image by varying the size and shape of the pixels. Often used
to get rid of artifacts and distortion caused by lowering the number of
colors in a GIF image file.
DPI
(dots per inch)
A measurement of the resolution of a
displayed image. The more dots per inch, the higher the resolution, and
therefore quality of the image. For example, 92 DPI means 92 dots
horizontally and 92 dots vertically, which equals 8464 dots per square
inch.
GIF
Originally created in 1987 by Compuserve,
the GIF (Graphics Interchange Format) is another of the most popular image
formats found today. GIF images may contain up to 256 colors or shades of
grey, and they may also contain transparency and animation. GIF
compression is lossless, and file sizes can be more precisely controlled
because a user can determine the exact number of colors they would like
the file to contain.
jaggies
Individual pixels displayed in an image with low resolution. The
appearance of pixels in an image cause lines and curves to look jagged.
JPG, JPEG
One of the most popular image formats, JPG is a lossy form of compression.
The amount of compression is variable, and more compression leads to
increased deterioration of the image. JPG images can display millions of
colors.
lossless compression
A form of compression where no data is
lost, and, therefore, does not affect image quality.
lossy compression
A form of compression that attempts to
discard unnecessary data. This data loss can affect the quality of the
image.
pixel
(PICture ELement)
The smallest piece of a digital image, arranged in rows and
columns.
PPI (pixels
per inch)
A measurement of how an image is displayed. The greater the number of
pixels per inch, the higher the quality of the image.
raster image
An image composed of a rectangular grid of
pixels. Each pixel contains a defined value about its color, size, and
location in the image. Therefore, resizing the image can affect its
quality.
resolution
The quality and clarity of an image,
measured in pixels, dots per inch, or pixels per inch.
TIF, TIFF
The Tagged Image File Format is robust and
often used for transporting high quality image files. TIF files may come
in compressed or uncompressed versions. TIF compression is lossless and
significantly reduces file size with no loss to the quality of the image.
vector image
An image made up of individual objects instead of pixels. The objects
are defined by mathematical equations. You can adjust the size of a vector
image and the image remains clear and of high quality.
Can't find a term on this
list? Then you're not being held responsible for knowing it on the quiz.
However, you should still look it up. Check out these resources, which are
consulted and cited in this listing:
ACD Digital Imaging Glossary,
Digital
Imaging Glossary
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