2012

Table Of Contents
adaptive sampling
A method to accelerate the anti-aliasing process within the bounds of the
sample matrix size. See also anti-aliasing.
adjacent cell selection
A selection of table cells that share at least one boundary with another cell in
the same selection.
alias
A shortcut for a command. For example, CP is an alias for COPY, and Z is an
alias for ZOOM. You define aliases in the acad.pgp file.
aliasing
The effect of discrete picture elements, or pixels, aligned as a straight or curved
edge on a fixed grid appearing to be jagged or stepped. See also anti-aliasing.
aligned dimension
A dimension that measures the distance between two points at any angle. The
dimension line is parallel to the line connecting the dimension's definition
points. (DIMALIGNED)
alpha channel
Alpha is a type of data, found in 32-bit bitmap files, that assigns transparency
to the pixels in the image.
A 24-bit truecolor file contains three channels of color information: red, green,
and blue, or RGB. Each channel of a truecolor bitmap file is defined by 8 bits,
providing 256 levels of intensity. The intensity of each channel determines
the color of the pixel in the image. Thus, an RGB file is 24-bit with 256 levels
each of red, green, and blue.
By adding a fourth, alpha channel, the file can specify the transparency, or
opacity, of each of the pixels. An alpha value of 0 is transparent, an alpha
value of 255 is opaque, and values in between are semi-transparent. An RGBA
file (red, green, blue, alpha) is 32-bit, with the extra 8 bits of alpha providing
256 levels of transparency.
To output a rendered image with alpha, save in an alpha-compatible format
such as PNG, TIFF, or Targa.
826 | Glossary