Geografic-Information-System/display/d.colors/d.colors.html

<h2>DESCRIPTION</h2>

A color table file associates specific colors with the categories of a
raster map layer. The user can change these map category color assignments
(i.e., change the map's color table) interactively, by first displaying the
raster map to the graphics monitor and then running the program
<em>d.colors</em>.

<p>Any color changes made using <em>d.colors</em> will not immediately be
shown on the graphics display; however, any color changes saved will
still alter the map's color table and will appear next time the raster
map layer is redisplayed (see <em><a href="d.colortable.html">d.colortable</a></em>).

<p>The user must first display the relevant raster map layer to the
active frame on the graphics monitor (e.g., using
<em><a href="d.rast.html">d.rast</a></em>) before running
<em>d.colors</em>. The user can then either enter the name of the
raster map layer whose color table is to be changed on the command
line (e.g., by typing: <tt>d.colors map=soils</tt>), or type
<tt>d.colors</tt> without program arguments. If the user simply types
<tt>d.colors</tt> without program arguments on the command line,
<em>d.colors</em> will ask the user to enter the name of an existing
raster map layer using the standard GRASS interface.

<p>In either case, the user is then presented with the <em>d.colors</em>
command menu, shown below.
<!-- This menu is the same as the category and color
changing portion of the <em><a href="d.display.html">d.display</a></em>
menu. -->
The <em>d.colors</em> commands are listed beneath the Category
Pointer Movement, Color Modification, Replotting Screen, and Quitting
sections below.  Commands are invoked by typing in the single-key response
shown to the left below. (Longer descriptions of these commands appear to
the right.) Results from invoking these commands will be reflected in the
Category and Category Number sections of the <em>d.colors</em> screen. On
the <em>d.colors</em> screen menu, commands appear in the right half of the
screen, and the current status of categories appears in the left half of the
screen.

<pre>
CATEGORIES
   0    No Data
   1    (Category 1 description)
   2    (Category 2 description)
   .    ....
   .    ....
CATEGORY NUMBER:
   RED         0   0%
   GREEN       0   0%
   BLUE        0   0%
Shift Incr:   10   3%
CATEGORY POINTER MOVEMENT
   D/d  down (cats)        Move pointer to next category
   U/u  up   (cats)        Move pointer to previous category
COLOR MODIFICATIONS
   R/r  RED                Increase/decrease RED intensity
   G/g  GREEN              Increase/decrease GREEN intensity
   B/b  BLUE               Increase/decrease BLUE intensity
   I/i  increment          Increase/decrease increment 
                           (of intensity shift)
   h    highlight          Highlight current color
   +/-  shift colors       Shift entire color table (up/down)
   c    save color         Save color table
   t    toggle table       Toggle to different color table
REPLOTTING SCREEN
   *    Replot screen      Replots the screen
QUITTING
   Q    quit               Quits program
</pre>

Changing categories - The keys 
<b>"d, D, u,"</b>
and 
<b>"U"</b>
are used to move to a different category. The lower case letters move up, 
<b>u,</b>
and down, 
<b>d,</b>
the category list one category at a time. The upper case letters move 10 
categories at a time for fast movement. The cursor does wrap between the 
first and last categories. The current category is noted on the text screen 
with an arrow, and is indicated on the graphics screen by a box around the 
current color. 

<p>
Changing colors - The color associated with the current category can be 
changed with the 
<b>"R, r, G, g, B,"</b>
and 
<b>b</b>
keys. The upper case letters increase the intensities of 
red 
<b>R,</b>
green 
<b>G,</b>
and blue 
<b>B</b>
for the current category; the lower case letters decrease the intensities of 
these same colors for the current category. Video devices make all the 
colors of the spectrum by mixing red, green, and blue. For those 
accustomed to red, yellow, and blue being the primary colors, this can 
be confusing. For starters, yellow is made by mixing red and green. The 
intensities are listed on the text screen in as percentages. 

<p>
Keys <b>I</b> and <b>i</b> increase and decrease the
percentage change that each keystroke of one of the color
keys (<em>R, r, G, g, B, b</em>) causes in its respective
color. The increase increment is initially set to 10%.
Thus, pressing the <em>R</em> key would will increase the
red component of the current category by 10%.

<p>
Highlight - The 
<b>h</b>
key toggles between the current category color and the current 
highlight color. This color is initially black but can be modified as 
above while in highlight mode. Blinking can be accomplished by repeatedly 
striking the 
<b>h</b>
key. When changing to different categories using the movement keys as 
described above, while in highlight mode the category colors will be 
always left showing their actual colors. Only one category is highlighted 
at any one time. 

<p>
Saving the current color table - 
Pressing the <b>c</b> key will save the current color table as you have 
modified it. This table will then be used next time you 
display or paint this raster map layer. 

<p>
Color table toggle - Different types of color tables are suitable for 
different raster map layers. 
The key 
<b>t</b>
flips between the following color tables: red, green, blue color ramp; gray 
scale; smooth changing color wave; random colors; and the saved color table. 

<p>
Color table shift - The entire table is shifted up and down using the 
<b>+</b>
and 
<b>-</b>
keys. 

<p>
Quitting the <em>d.colors</em> program - Pressing the
<b>Q</b> key will cause you to quit the <em>d.colors</em>
program.  If colors have been modified but not saved,
<em>d.colors</em> will ask:
<pre>
         Colors changed
         Save the changes? (y/n)
</pre>
The user should type in <b>y</b> to save changes, 
or <b>n</b> to not save changes, before quitting the program. 
If the user types <b>n</b>, the program will ask: 
<pre>
         Quit anyway? (y/n) 
</pre>
<h2>NOTES</h2>

<p>
The map whose color table is to be altered with
<em>d.colors</em> must already be on display in the active
display frame on the graphics monitor before
<em>d.colors</em> is run. This can be done using the
command <em><a href="d.rast.html">d.rast</a> map=name</em> (where <em>name</em> is a raster map
layer whose color table the user wishes to alter).

<p>Some color monitors may not support the full range of colors required 
to display all of the map's categories listed in the map's color table. 
However, regardless of whether the user can see the color changes he is 
effecting to a map's color table, any changes to a map's color table 
made with <em>d.colors</em> that are saved will appear in the map's color table. 

<h2>SEE ALSO</h2>

<em>
<a href="d.colortable.html">d.colortable</a>,
<a href="d.rast.html">d.rast</a>,
<a href="r.colors.html">r.colors</a>
</em>

<h2>AUTHOR</h2>

James Westervelt, U.S. Army Construction Engineering 
Research Laboratory

<p><i>Last changed: $Date$</i>