1r.his(1)                    GRASS GIS User's Manual                   r.his(1)
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NAME

6       r.his   - Generates red, green and blue (RGB) raster map layers combin‐
7       ing hue, intensity and  saturation  (HIS)  values  from  user-specified
8       input raster map layers.
9

KEYWORDS

11       raster, color transformation, RGB, HIS, IHS
12

SYNOPSIS

14       r.his
15       r.his --help
16       r.his   [-c]   hue=string    [intensity=string]     [saturation=string]
17       red=string  green=string  blue=string   [bgcolor=name]    [--overwrite]
18       [--help]  [--verbose]  [--quiet]  [--ui]
19
20   Flags:
21       -c
22           Use colors from color tables for NULL values
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24       --overwrite
25           Allow output files to overwrite existing files
26
27       --help
28           Print usage summary
29
30       --verbose
31           Verbose module output
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33       --quiet
34           Quiet module output
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36       --ui
37           Force launching GUI dialog
38
39   Parameters:
40       hue=string [required]
41           Name of layer to be used for hue
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43       intensity=string
44           Name of layer to be used for intensity
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46       saturation=string
47           Name of layer to be used for saturation
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49       red=string [required]
50           Name of output layer to be used for red
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52       green=string [required]
53           Name of output layer to be used for green
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55       blue=string [required]
56           Name of output layer to be used for blue
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58       bgcolor=name
59           Color to use instead of NULL values
60           Either a standard color name, R:G:B triplet, or "none"
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DESCRIPTION

63       HIS  stands  for hue, intensity, and saturation.  This program produces
64       red, green and blue raster map layers  providing  a  visually  pleasing
65       combination  of hue, intensity, and saturation values from two or three
66       user-specified raster map layers.
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68       The human brain automatically interprets  the  vast  amount  of  visual
69       information available according to basic rules.  Color, or hue, is used
70       to categorize  objects.   Shading,  or  intensity,  is  interpreted  as
71       three-dimensional  texturing. Finally, the degree of haziness, or satu‐
72       ration, is associated with distance or depth. This program allows  data
73       from  up  to  three raster map layers to be combined into a color image
74       (in the form of separate red, green and blue raster map  layers)  which
75       retains  the original information in terms of hue, intensity, and satu‐
76       ration.
77
78       While any raster map layer can be used to represent  the  hue  informa‐
79       tion,  map  layers  with  a  few  very distinct colors work best.  Only
80       raster map layers representing continuously varying  data  like  eleva‐
81       tion,  aspect, weights, intensities, or amounts can suitably be used to
82       provide intensity and saturation information.
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84       For example, a visually pleasing image can be made by using a watershed
85       map  for the hue factor, an aspect map for the intensity factor, and an
86       elevation map for saturation. (The user may wish to leave out the  ele‐
87       vation  information  for  a  first  try.)  Ideally, the resulting image
88       should resemble the view from an aircraft looking at  a  terrain  on  a
89       sunny day with a bit of haze in the valleys.
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91   The Process
92       Each  map  cell  is processed individually. First, the working color is
93       set to the color of the corresponding cell in the map layer  chosen  to
94       represent  hue.   Second, this color is multiplied by the red intensity
95       of that cell in the intensity map layer.  This map layer should have an
96       appropriate  gray-scale  color table associated with it. You can ensure
97       this  by  using  the  color  manipulation  capabilities  of   r.colors.
98       Finally,  the color is made somewhat gray-based on the red intensity of
99       that cell in the saturation map layer.  Again, this  map  layer  should
100       have a gray-scale color table associated with it.
101

NOTES

103       The name is misleading. The actual conversion used is
104         H.i.s + G.(1-s)
105       where
106         H   is the R,G,B color from the hue map
107         i   is the red value from the intensity map
108         s   is the red value from the saturation map
109         G   is 50% gray (R = G = B = 0.5)
110
111       Either (but not both) of the intensity or the saturation map layers may
112       be omitted. This means that it is possible  to  produce  output  images
113       that represent combinations of his, hi, or hs.  The separate red, green
114       and blue maps can be displayed on the graphics monitor using d.rgb,  or
115       combined  into  a composite RGB layer using r.composite.  Users wishing
116       to simply display an his composite image  without  actually  generating
117       any layers should use the program d.his.
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EXAMPLES

120       Recreate  the  following  example for d.his using r.his.  First, create
121       shaded relief and show it.
122       g.region raster=elevation
123       r.relief input=elevation output=elevation_shaded_relief
124       d.mon wx0
125       d.his hue=elevation intensity=elevation_shaded_relief brighten=50
126       Second, compute lighter version of color of shaded relief.   Then  con‐
127       vert from HIS model to RGB and show the result.
128       r.mapcalc "elevation_shaded_relief_bright_50 = #elevation_shaded_relief * 1.5"
129       r.colors elevation_shaded_relief_bright_50 color=grey255
130       r.his hue=elevation intensity=elevation_shaded_relief_bright_50 \
131             red=shadedmap_r green=shadedmap_g blue=shadedmap_b
132       d.mon wx1
133       d.rgb red=shadedmap_r green=shadedmap_g blue=shadedmap_b
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SEE ALSO

136        d.his, d.colortable, d.rgb, r.blend, r.colors, r.composite, r.mapcalc,
137       r.shade, i.his.rgb, i.rgb.his
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AUTHOR

140       Glynn Clements (based upon d.his)
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SOURCE CODE

143       Available at: r.his source code (history)
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145       Main index | Raster index | Topics index | Keywords index  |  Graphical
146       index | Full index
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148       © 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual
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152GRASS 7.8.5                                                           r.his(1)
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