Essential Web Graphics
What All Web Designers Should Know
Glossary
Please note that this is not intended to be a complete glossary of all Web-related terminology. The terminology currently defined here represents the presentation only, though more definitions may be added. If you have terms that you'd like to add, please contact Cyndi.
- Accessibility: easily approached or entered; easily obtained regardless
of disability
- Aliasing:
resampling of the foreground color in context to the background
color within an image. The best way to understand aliasing is with an
example.
- Color depth: also
referred to as bit depth or the number of colors contained in the image
color table. If an image color table contains 256 colors that image
would be an 8-bit image. If the color table contains 2 colors, it would
be a 1-bit image. The more colors an image has, the more bit depth the
it has -- and the larger its file size.
- Color table: the colors used to define the image, also
referred to as color palette.
The
two types of color tables are RGB ( also referred to as true color)
and indexed (also called a CLUT or Color Look Up Table).
- Communication:
the transfer or exchange of thoughts, messages, or information.
- Compression: the
process by which data is compressed into a form that minimizes the
space required to store or transmit it.
- Dithering: the alternating
dots of two or more colors, typically to blend between colors or
to
create a new color not found in the color table. From a distance, a
dithered color will appear to be a single color. Older, 8-bit monitors
also use
dithering to display colors that are not present in the system palette.
Use the Web safe (or 216-color table) to avoid having this adversely
affect your images.
- Transparency: in
image formats that support transparency, it is pixels turned ON or OFF (OFF representing transparency). Transparency is defined by either a mask
(alpha channel) or color (GIF98-popular.)
- Usability: the effectiveness and efficiency with which users can achieve tasks in a particular environment
