NAME

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

KEYWORDS

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

SYNOPSIS

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

   Flags:
       -n
           Respect NULL values while drawing

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

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

       intensity=string
           Name of layer to be used for intensity

       saturation=string
           Name of layer to be used for saturation

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

DESCRIPTION

       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.

OPTIONS

       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.

THE PROCESS

       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.

NOTES

       The name is misleading. The actual conversion used is
         H.i.s + G.(1-s)
       where
         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.

EXAMPLE

       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

SEE ALSO

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

AUTHOR

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

SOURCE CODE

       Available at: d.his source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual