i.landsat.rgb(1)

1i.landsat.rgb(1)              Grass User's Manual             i.landsat.rgb(1)
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NAME

6       i.landsat.rgb  - Auto-balancing of colors for LANDSAT images
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KEYWORDS

9       raster, imagery, colors
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SYNOPSIS

12       i.landsat.rgb
13       i.landsat.rgb help
14       i.landsat.rgb     [-fpr]     red=string     green=string    blue=string
15       [strength=integer]
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17   Flags:
18       -f  Extend colors to full range of data on each channel
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20       -p  Preserve relative colors, adjust brightness only
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22       -r  Reset to standard color range
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24   Parameters:
25       red=string
26           LANDSAT red channel
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28       green=string
29           LANDSAT green channel
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31       blue=string
32           LANDSAT blue channel
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34       strength=integer
35           Cropping intensity (upper brightness level) Options: 0-100 Default:
36           98
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DESCRIPTION

39       i.landsat.rgb  auto-balances and enhances the color channels of a LAND‐
40       SAT RGB image to provide a more natural color mixture. Only  the  color
41       table of each image band is modified, the base data remains untouched.
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43       The  module works by calculating a histogram for each color channel and
44       removing an adjustable amount of outliers from either end before recal‐
45       ibrating the color scale with r.colors.
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47       It  will  work  with any 8-bit RGB imagery set and the script is easily
48       modified to work with other datasets of greater band-depth.
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NOTES

51       Depending on the image, it may or may not be advantageous to use the -p
52       flag  to  preserve the relative color scaling. You will have to experi‐
53       ment with the different options to find a setting that works  best  for
54       your particular imagery.
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56       The  strength  option  should  generally be set in the 90-99 range. The
57       lower the number, the more saturated the image becomes.  It  represents
58       the  percentage  cut-off  for the top end of the color histogram curve.
59       The lower end is fixed at 2% of the area under the curve.
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61       For quicker execution of this module on large images  you  can  achieve
62       largely similar results by switching to a coarser resolution before the
63       running of the module (using g.region) and then back  to  the  original
64       resolution afterwards.
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EXAMPLE

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68       i.landsat.rgb red=tm.3 green=tm.2 blue=tm.1
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TODO

72       The strength option requires further refinement.
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74       Update  to  use  r.univar instead of r.univar.sh once r.univar receives
75       extended statistics support.
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AUTHORS

81       Markus Neteler
82       M. Hamish Bowman, Dept. Marine Science, Otago University, New Zealand
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84       Last changed: $Date: 2007/03/08 13:51:30 $
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86       Full index
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90GRASS 6.2.2                                                   i.landsat.rgb(1)