NAME
GenerateStdColormap
DESCRIPTION
This module generates and displays colormaps in its control panel. It is
quicker than having to use GenerateColormap, possibly in conjunction
with WriteLat/ReadLat modules. In the Unix versions, an obvious
disadvantage of GenerateColormap is that it allocates many colors from
the root window's colormap since it uses the same visual and colormap
as the root window. If the root window is 8-bit (which it usually is) then
you can barely run two or three GenerateColormap modules before all
the colors are used up. GenerateStdColormap solves this problem by
displaying the colormap in a custom "TrueColor" (usually 24-bit RGB)
drawing area. On SGI machines at least, it should be possible to run as
many GenerateStdColormap modules as necessary without a color
allocation problem since no colors are allocated from the root window.
See "KNOWN PROBLEMS" further below for compatibility information.
In addition to displaying colormaps, GenerateStdColormap can
generate a black to a user-defined color, a user-defined color to black,
blue to red, red to blue, purple (really magenta) to red, red to purple, or
a solid-color colormap. The user defined colors are derived from the
settings of the "Red", "Green", "Blue", and "Opacity" sliders. The
opacity setting is used for all the colormaps except the input one.
GenerateStdColormap can take in a data lattice and a colormap lattice.
If a data lattice is present then the minimum and maximum widgets can
be set based on its values, optionally ignoring special values. If a
colormap is present then its colors and minimum and maximum can be
used for the output colormap. The minimum and maximum values of a
data lattice will override those of a colormap if both are connected,
however, both can also be overridden to remain user-adjustable. Input
colormaps and the internally generated ones can be an arbitrary size;
256 colors is usually the default.
INPUTS
Colormap In -- Lattice (Opt.)
(1-D, 3..4-vector, float, uniform).
This is an input colormap which can be used as the output colormap.
Data In -- Lattice (Opt.)
This is an input data lattice whose data values are used to set the
minimum and maximum widgets for the output colormap.
WIDGETS
Colormap Type -- Option Menu
This specifies the color range to use for the output colormap.
Black To Color - Black to a color defined by the color sliders.
Color To Black - A color defined by the color sliders to black.
Blue To Red - A uniform rainbow from blue to red.
Red To Blue - A uniform rainbow from red to blue.
Purple To Red - A uniform rainbow from purple to red.
Red To Purple - A uniform rainbow from red to purple.
Solid Color - A single color defined by the color sliders.
Colormap In - Use the input colormap.
Reverse Colormap In - Use the input colormap but reverse the order
of the colors
Minimum -- Dial
This is the lower bound of the colormap's coordinate range.
Maximum -- Dial
This is the upper bound of the colormap's coordinate range.
Red -- Slider
This is the red component of the user-defined colors.
Green -- Slider
This is the green component of the user-defined colors.
Blue -- Slider
This is the blue component of the user-defined colors.
Opacity -- Slider
This is the opacity component of the user-defined colors.
Colormap Window -- Drawing Area
This is a graphical representation of the colormap in a "TrueColor"
(usually 24-bit RGB) drawing area.
# Colors -- Slider
This is the number of colors to be used for the output colormap. The
only limitation is that it must be greater than 0. If the input colormap is
used then this value will be set to its number of colors whenever new
colormap data arrives. If the number of colors is not the same as the
input colormap then new ones will be interpolated.
Remove Special? -- Option Menu
This determines whether data values from an input lattice that match
the "Special Value" are included when finding the bounds of the
coordinate range.
Special Value -- Text
This is data value that should be treated as "special" when "Remove
Special?" is set to "Yes".
Input Coords? -- Option Menu
Setting this to "Yes" will specify to always use the coordinates from
either the input colormap or data lattices (if they are connected) to set
the minimum and maximum values for the output colormap. The
coordinates from a data lattice will take precedence over those from a
colormap lattice.
OUTPUTS
Colormap Out -- Lattice
(1-D, 4-vector, float, uniform).
This is the new output colormap.
KNOWN PROBLEMS
There is no interactive spline-based color editing (a possible future
addition). This module may only work on SGI machines with no later than
Explorer 3.0 because it relies on the old Iris GL library (not the newer
OpenGL) for drawing into an area on the control panel. Compatibility for
all SGI machines isn't known either; it probably depends on how the Iris
GL library is implemented. The machine should also be able to display
"TrueColor" visuals, preferably at least 24-bit RGB for best results.
Please report any incompatibilities to the address below. There are no
known bugs.
SEE ALSO
ColorBands, GenerateColormap GenOneColor
-
Hans Vahlenkamp (Hans.Vahlenkamp@noaa.gov)
Geophysical Fluid Dynamics Laboratory / NOAA
Princeton University Forrestal Campus
http://www.gfdl.noaa.gov
