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i.his.rgb.1grass - Man Page

Transforms raster maps from HIS (Hue-Intensity-Saturation) color space to RGB (Red-Green-Blue) color space.


imagery, color transformation, RGB, HIS, IHS


i.his.rgb --help
i.his.rgb hue=name intensity=name saturation=name red=name green=name blue=name  [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]



Allow output files to overwrite existing files


Print usage summary


Verbose module output


Quiet module output


Force launching GUI dialog


hue=name [required]

Name of input raster map (hue)

intensity=name [required]

Name of input raster map (intensity)

saturation=name [required]

Name of input raster map (saturation)

red=name [required]

Name for output raster map (red)

green=name [required]

Name for output raster map (green)

blue=name [required]

Name for output raster map (blue)


i.his.rgb is an image processing program that processes three input raster map layers as hue, intensity and saturation components and produces three output raster map layers representing the red, green and blue components of this data.  The output raster map layers are created by a standard hue-intensity-saturation (HIS) to red-green-blue (RGB) color transformation.  Each output raster map layer is given a linear gray scale color table.  The current geographic region and mask settings are respected.


It is not possible to process three bands with i.his.rgb and then exactly recover the original bands with i.rgb.his. This is due to loss of precision because of integer computations and rounding.  Tests have shown that more than 70% of the original cell values will be reproduced exactly after transformation in both directions and that 99% will be within plus or minus 1.  A few cell values may differ significantly from their original values.

See Also

i.rgb.his, r.colors


David Satnik, GIS Laboratory, Central Washington University

with acknowledgements to Ali Vali, Univ. of Texas Space Research Center, for the core routine.

Source Code

Available at: i.his.rgb source code (history)

Accessed: Tuesday Mar 19 11:02:28 2024

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