d.his(1grass) GRASS GIS User's Manual d.his(1grass)
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, in-
tensity, and saturation values from two or three user-specified raster
map layers.
The human brain automatically interprets the vast amount of visual in-
formation 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 satu-
ration, 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 satu-
ration.
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 (satu-
ration). 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 informa-
tion, map layers with a few very distinct colors work best. Only
raster map layers representing continuously varying data like eleva-
tion, 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 ele-
vation 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. Fi-
nally, 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 Labora-
tory
SOURCE CODE
Available at: d.his source code (history)
Accessed: unknown
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GRASS 7.8.7 d.his(1grass)
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