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       d.his   -  Displays  the result obtained by combining hue, intensity, and saturation (HIS)
       values from user-specified input raster map layers.


       display, graphics, color transformation, RGB, HIS, IHS


       d.his --help
       d.his  [-n]  hue=string   [intensity=string]    [saturation=string]     [brighten=integer]
       [--help]  [--verbose]  [--quiet]  [--ui]

           Respect NULL values while drawing

           Print usage summary

           Verbose module output

           Quiet module output

           Force launching GUI dialog

       hue=string [required]
           Name of layer to be used for hue

           Name of layer to be used for intensity

           Name of layer to be used for saturation

           Percent to brighten intensity channel
           Options: -99-99
           Default: 0


       HIS  stands  for hue, intensity, and saturation.  This program produces a raster map layer
       providing a visually pleasing combination of hue, intensity, and  saturation  values  from
       two or three user-specified raster map layers.

       The  human  brain automatically interprets the vast amount of visual information available
       according to basic rules.  Color, or hue, is used  to  categorize  objects.   Shading,  or
       intensity, is interpreted as three-dimensional texturing. Finally, the degree of haziness,
       or saturation, is associated with distance or depth. This program allows data from  up  to
       three  raster  map  layers  to  be  combined  into  an  image  which  retains the original
       information in terms of hue, intensity, and saturation.


       This program can be run non-interactively or interactively.  It will run non-interactively
       if  the  user specifies on the command line the name of a map containing hue values (hue),
       and the name(s) of map(s) containing intensity values (intensity) and/or saturation values
       (saturation).   The  resulting  image will be displayed in the active display frame on the
       graphics monitor.

       Alternately, the user can run the program interactively by  typing  d.his  without  naming
       parameter  values on the command line.  In this case, the program will prompt the user for
       parameter values using the standard GRASS GUI interface.

       While any raster map layer can be used to represent the hue information, map layers with a
       few  very  distinct  colors  work  best.  Only raster map layers representing continuously
       varying data like elevation, aspect, weights, intensities, or amounts can suitably be used
       to provide intensity and saturation information.

       For  example,  a  visually pleasing image can be made by using a watershed map for the hue
       factor, an aspect map for the intensity factor, and an elevation map for saturation.  (The
       user  may  wish  to  leave  out  the elevation information for a first try.)  Ideally, the
       resulting image should resemble the view from an aircraft looking at a terrain on a  sunny
       day with a bit of haze in the valleys.

       The  brighten  option does not truly represent a percentage, but calling it that makes the
       option easy to understand, and it sounds better than Normalized Scaling Factor.


       Each map cell is processed individually. First, the working color is set to the  color  of
       the  corresponding  cell  in the map layer chosen to represent hue.  Second, this color is
       multiplied by the red intensity of that cell in the intensity map layer.  This  map  layer
       should  have an appropriate gray-scale color table associated with it. You can ensure this
       by using the color manipulation capabilities of r.colors.   Finally,  the  color  is  made
       somewhat gray-based on the red intensity of that cell in the saturation map layer.  Again,
       this map layer should have a gray-scale color table associated with it.


       The name is misleading. The actual conversion used is
         H.i.s + G.(1-s)
         H   is the R,G,B color from the hue map
         i   is the red value from the intensity map
         s   is the red value from the saturation map
         G   is 50% gray (R = G = B = 0.5)

       Either (but not both) of the intensity or the saturation map layers may be  omitted.  This
       means that it is possible to produce output images that represent combinations of his, hi,
       or hs.

       Users wishing to store the result in new raster map layers instead of displaying it on the
       monitor should use the command r.his.


       g.region raster=elevation
       r.relief input=elevation output=elevation_shaded_relief
       d.mon wx0
       d.his hue=elevation intensity=elevation_shaded_relief brighten=50


        d.colortable, d.frame, d.rgb, d.shade, r.colors, r.his, i.his.rgb, i.rgb.his


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

       Last changed: $Date: 2014-12-20 05:56:06 +0100 (Sat, 20 Dec 2014) $

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