AFNI file: README.setup
Setting Up AFNI Colors and Palettes
You can set up the colors and palette tables used by AFNI in the
file .afnirc in your home directory. This file will be read when
AFNI starts. Each section of this file starts with a string of
the form "***NAME", where "NAME" is the name of the section. At
present, three sections are available:
***COLORS -- for defining new colors
***PALETTES -- for defining the layout of colors used for
functional overlays (the "palette tables").
***ENVIRONMENT -- for defining Unix environment variables that
affect the way AFNI works.
Note that you can have more than one of each section in the setup
file (although there is no particular reason why this is needed).
Comments can be put in the .afnirc file using the C++ "//" style:
everything from the "//" to the end of line will be ignored.
The file AFNI.afnirc in the afni98.tgz distribution contains
an example of defining colors and using them to create palettes
for functional overlay.
Defining the Colors Available for Overlays
The "***COLORS" section is used to define colors that will be added
to the color menu that is used for functional overlays, crosshairs,
etc. A sample is
qblue = #804cff // RGB hexadecimal color definition
zblue = rgbi:0.5/0.3/1.0 // RGB floating point intensities
The general form of a color definition line is
label = definition
where "label" is what you want to appear on the menu, and "definition"
is a valid X11 color definition. (The spaces around "=" are required.)
In the first line, I have defined the label "qblue" using hexadecimal
notation for the RGB components (each one has 2 hex digits). In the
second line, I have defined the color "zblue" using the RGB intensity
format, where each of the numbers after the string "rgbi:" is between
0.0 and 1.0 (inclusive) and indicates the intensity of the desired color
Note that the file /usr/lib/X11/rgb.txt (or its equivalent) contains
the definitions of many color names that the X11 system recognizes.
See 'man XLookupColor' for more information on the many ways to define
colors to X11.
If you use a label that has been defined previously (either internally
within AFNI, or earlier in the setup file), then that color will be
redefined. That is, you could do something stupid like
blue = red
and AFNI won't complain at all. ("blue" is one of the pre-defined colors
in AFNI. I suppose you could use this 'feature' to make AFNI into some
sort of twisted Stroop test.) Color labels are case sensitive, so
"BLUE = red" is different than "blue = red". You cannot redefine the
On 8 bit graphics systems (the vast majority), you must be parsimonious
when defining new colors. You may run out of color "cells", since there
are only 2**8 = 256 available at one time. All the colors used for
the windowing system, the buttons, the grayscale images, and the overlays
must come from this limited reservoir. On a 12 bit system (e.g., SGI),
there are 2**12 = 4096 color cells available, which is effectively
Defining the Palette Tables
A palette is a listing of colors and separating numerical values that
are used to define a functional overlay scheme. These are controlled
by the "***PALETTES" section in the setup file. Each palette has a
name associated, and a number of color "panes". For example:
1.0 -> blue // The spaces around "->" are required
0.2 -> green
-0.4 -> hotpink // There are N lines for palette entry [N]
This defines a palette table "rainbow", and in the entry for 3 panes
sets up the pbar to have 1.0 as its maximum value, then to have the
color "blue" be assigned to the pane that runs down to 0.2, then the
color "green" assigned to the next pane running down to -0.4, and then
the color "hotpink" assigned to the last pane (which will run down to
-1.0, since the minimum value is the negative of the maximum value).
Each palette table can have palettes from 2 panes up to 20, denoted
by  to . A palette table, can also have palettes that are
restricted to positive values only. These are denoted by [2+] to
[20+]. An example is
1.0 -> blue
0.5 -> none
0.1 -> limegreen
If the rainbow palette is the active one, when you switch to positive-
only function mode (using the "Pos" toggle button), and then to use 3
panes (using the "#" chooser), then the top pane will run from 1.0 to
0.5 in blue, the second pane from 0.5 to 0.1 and have no color, and the
third pane from 0.1 to 0.0 in limegreen.
It is possible to define palettes that only change the colors,
not the separating values. This is done by using the special
word IGNORE in place of the values:
IGNORE -> blue
IGNORE -> green
IGNORE -> hotpink
IGNORE -> none
All of the values must be IGNORE, or none of them. When a
palette like the one above is loaded, only the colors in the
pbar will change -- the pane heights will be left unchanged.
The New Palette Menu
Attached to the "Inten" label atop the color pbar is a popup menu
that is activated using mouse button 3. This menu has the following
Equalize Spacing = Sets the spacings in the currently visible
palette to be uniform in size.
Set Top Value = Sets the top value in the currently visible
palette to a number you choose. Note that
you will probably need to adjust the
"Range" control if you change the top value
from 1.0, since the thresholds for making
functional overlays are determined by
multiplying the pbar values times the
value in the "Range" or "autoRange" control.
Read in palette = Reads in a palette file. This is another
file like .afnirc (with ***COLORS and/or
***PALETTES sections). AFNI expects such
files to have names that end in ".pal".
N.B.: New colors defined this way will NOT be visible
on previously created color menus (such as the
Crosshairs Color chooser), but will be visible
on menus created later.
N.B.: Reading in a palette that has the same name
as an existing one will NOT create a new one.
Write out palette = Writes out the currently visible palette to
a ".pal" file. In this way, you can set up
a palette that you like, write it out, and
then read it back in later. (Or you could
copy the data into your .afnirc file, and
it would be available in all later runs.)
The program asks you for a palette name,
which is also used to for the filename -- if
you enter "elvis" for the palette name, then
AFNI will write to the file "elvis.pal". If
this file already exists, the palette is
appended to the end of the file; otherwise,
the file is created.
Show Palette Table = Pops up a text window showing the definitions
of all the colors and palettes. Mostly useful
for debugging purposes.
Set Pal "chooser" = A menu that lets you pick the palette table
that is currently active. Note that reading
in a palette table does not make it active --
you must then choose it from this menu. Writing
a palette out does not enter it into this menu.
======>>> N.B.: If a palette table does not have an entry for a
given number of panes, then nothing will happen
until you use the "#" chooser to make the number
of panes correspond to the selected palette table.
=> 18 Sep 1998: In versions of AFNI released after this date,
reading in a palette file causes the last
palette in that file to become the active one.
[Suggested by SM Rao of MCW Neuropsychology]
Unix Environment Variables [June 1999]
You can set Unix environment variables for an interactive AFNI run in
the .afnirc file. This is done with the ***ENVIRONMENT section. An
AFNI_HINTS = YES
AFNI_SESSTRAIL = 3
The blanks around the "=" are required, since that is how the setup
processing routine breaks lines up into pieces. For a list of the
environment variables that affect AFNI, see README.environment.
I will probably add more sections to the setup file. Someday. Maybe.
| Robert W. Cox, PhD |
| National Institute of Mental Health |
| Bethesda, MD USA |
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Tue Feb 19 20:54:01 EST 2019