d.his(1)

📦
version 8.4.2 · 8 versions
, in fedora 44

d.his(1) 💖

okay bestie, welcome to the GRASS GIS User's Manual, display edition 🎀 this one's called d.his and it's giving color wizardry, fr fr.

✨ 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 💜

d.his displays the result obtained by combining hue, intensity, and saturation (HIS) values from user-specified input raster map layers. no cap.

HIS stands for hue, intensity, and saturation, obviously. ✨ 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. two or three, bestie, your choice.

so here's the science bit and it's honestly iconic: your human brain automatically interprets the vast amount of visual information available according to basic rules. color, aka hue, is used to categorize objects. shading, aka intensity, gets interpreted as three-dimensional texturing. and finally, the degree of haziness, aka saturation, is associated with distance or depth. main character brain behavior honestly 🧠✨ this program lets data from up to three raster map layers be combined into an image which retains the original information in terms of hue, intensity, and saturation. slay.

💅 OPTIONS 💅

this program can be run non-interactively or interactively, pick your vibe. 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. so chill, it'll walk you through it.

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. like, that's the rule, i don't make it.

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. it's giving window seat on a plane, periodt. 🛩️🌈

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. yeah they said it, not me 💀

🔥 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. same rule, second time, don't forget 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. cute, right? 🎀

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

🌈 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)

Accessed: Saturday Jan 17 05:40:35 2026

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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual

okay that's the whole thing, bestie 💅 this was GRASS 8.4.2, accessed Saturday Jan 17 05:40:35 2026, © 2003-2025 GRASS Development Team — and yeah, that's the GRASS GIS 8.4.2 Reference Manual, mwah, go make something pretty with it ✨🌸🫶

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