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G.1 NCSA ImageTool
Glossary G.1
National Center for Supercomputing Applications
January 1991
January 1991
Glossary
Canvas
A window where drawing operations may be performed.
Click
An action performed on a mouse button by rapidly pressing and
releasing it.
Color Look-up Table
A listing of the set of colors currently used by the hardware to
display color images. This table defines the mapping of color to
pixel value. There is only one color look-up table, but its contents
can change. This may also be referred to as a clut.
Color Palette or Palette
A palette to retain a group of colors. Palettes are used to initialize
the color look-up table. A palette for each image stores the colors to
be used with the image.
Color Strip
Values inserted into a file or displayed on the canvas that indicate
the range of colors, with 0 at the extreme left and 255 at the extreme
right. A color strip is used to represent all 256 colors in a palette.
Contour Level
A range of data values that is to be distinguished from other
ranges.
Contour Line
The visual representation of the division between two contour
levels.
Contour Plot
A representation of a raster file that shows a series of contour lines
separating different contour levels.
Control Button
A visual button on the computer screen that performs some function
when the left mouse button is clicked on it. Control buttons are
usually rectangular with rounded edges and typically contain
some descriptive text.
Current Directory
The directory in the file system where ImageTool will look for
files to be loaded.
Dimensions
The number of rows and columns in the data matrix.
Frame
A rectangle that encloses a group of windows and/or panels or a
single window or panel.
HDF
HDF (Hierarchical Data Format), created at NCSA, is a multi-
object file structure designed to facilitate the sharing of data
among people, projects, and machines on a network.
HSI
The color model that represents color as a combination of hue,
saturation, and intensity (brightness).
Image
A pictorial representation of the raster file data that is displayed
when you select the Load option. ImageTool uses a color
representation.
Insertion point
The point in a text field, indicated by a blinking triangular cursor,
where text is displayed when you press on the keyboard.
Locator
The dark gray area displayed in a scroll bar. It indicates the
position within the text that is currently being viewed within the
window.
Magnification
The distance between adjacent data points. When the
magnification is 1, each pixel or dot on the screen represents a data
point.
Mouse
Either of two related items: the hardware device that is used to
move a pointer around on the computer screen or the pointer itself.
The term refers collectively to both of these elements throughout
this text. For example, the statement "move the mouse onto the
canvas" means that you should move the hand-held hardware
device on the grid until the mouse pointer has moved onto the
canvas area. Movement of the hardware mouse will cause
corresponding movement of the mouse pointer on the screen.
Mouse Button
The three buttons on the mouse device. They are individually
referred to as the left, middle, or right mouse button.
Origin Point
The location on the canvas where the next drawing operation will
begin.
Palette
An array of 256 RGB colors. (The colors are not necessarily
different.)
Palette File
A file containing 256 RGB colors that can be used to initialize the
color look-up table. When a raster file is first loaded, the palette
used for the image is a duplicate of the color look-up table. You can
then modify the palette or load a different palette from a palette file.
Paste Buffer
The storage area where data that is cut or copied is stored so that it
may be recalled.
Pitch
Rotation around the horizontal axis (x axis), measured in degrees.
Plot, Line Plot
Any visual representation of a set of data points. A line plot is any
black-and-white representation of the data set.
Raster File
A file containing a data matrix represented by a stream of bytes.
RGB
The color model that represents all color as some combination of
red, green, and blue.
Roll
Rotation around the z axis, measured in degrees.
Scroll Arrows
Small triangular figures in the extremities of a scroll bar that are
used to interactively initiate scrolling.
Scroll Bar Content
The light gray area of a scroll bar.
Selection
An area of the canvas you designate interactively. Such an area
can be used for a contour or 3D plot or an editing function.
Spectrum
A diverse or varying range of colors. Unlike a palette, a spectrum
consists of a range of differing colors and does not always consist
of 256 colors. The fiddle operation alters the width and position of
the spectrum, but cannot change the width of the palette.
Text Field
An area in a window in which text may be entered and edited.
TTY Window
A window that is used for three-way communication between you,
the operating system, and ImageTool. ImageTool messages are
displayed in this window. You may also use this window to enter
system commands.
Yaw
Rotation about the vertical axis (y), measured in degrees.
3D Plot
A surface plot of the raster file representing the values in the 2D
matrix as points in 3D space.