i.colors.enhance - Performs auto-balancing of colors for RGB images.

       Markus Neteler, Trento, Italy
       M. Hamish Bowman, Dept. Marine Science, Otago University, New Zealand

i.colors.enhance auto-balances and enhances the color channels of a RGB  image  (e.g.  from  Landsat)  to
       provide  a more natural color mixture. Only the color table of each image band is modified, the base data
       remains untouched.

       The module works by calculating a histogram for each color channel and removing an adjustable  amount  of
       outliers from either end before recalibrating the color scale with r.colors.

       It will work with any 8-bit RGB imagery set and the script is easily modified to work with other datasets
       of greater band-depth.

       North Carolina sample dataset example with Landsat data:
       g.region raster=lsat7_2002_10 -p
       d.rgb blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30
       d.barscale at=55.3125,93.125 bcolor=white text_pos=over
       i.colors.enhance blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30 strength=95
       d.rgb blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30
       d.barscale at=55.3125,93.125 bcolor=white text_pos=over
       Uncorrected RGB composite of Landsat ETM channels B/G/R

       Color corrected RGB composite of Landsat ETM channels B/G/R

       imagery, RGB, satellite, colors

i.colors.enhance  - Performs auto-balancing of colors for RGB images.

       Depending  on  the  image,  it may or may not be advantageous to use the -p flag to preserve the relative
       color scaling. You will have to experiment with the different options to find a setting that  works  best
       for your particular imagery.

       The  strength option should generally be set in the 90-99 range. The lower the number, the more saturated
       the image becomes. It represents the percentage cut-off for the top end of the color histogram curve. The
       lower end is fixed at 2% of the area under the curve.

       For quicker execution of this module on large images you can achieve largely similar results by switching
       to a coarser resolution before the running of the module (using g.region) and then back to  the  original
       resolution afterwards.

d.rgb,g.region,i.oif,r.colors,r.composite,r.univar

       Available at: i.colors.enhance source code (history)

       Accessed: Friday Apr 04 01:21:11 2025

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       © 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual

GRASS 8.4.1                                                                             i.colors.enhance(1grass)

i.colors.enhancei.colors.enhance--helpi.colors.enhance   [-fprs]   red=namegreen=nameblue=name   [strength=float]    [--help]   [--verbose]
       [--quiet]  [--ui]

   Flags:-f
           Extend colors to full range of data on each channel

       -p
           Preserve relative colors, adjust brightness only

       -r
           Reset to standard color range

       -s
           Process bands serially (default: run in parallel)

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:red=name[required]
           Name of red channel

       green=name[required]
           Name of green channel

       blue=name[required]
           Name of blue channel

       strength=float
           Cropping intensity (upper brightness level)
           Options: 0-100
           Default: 98

       The strength option requires further refinement.