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]   [--verbose]  [--quiet]
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17   Flags:
18       -f
19           Extend colors to full range of data on each channel
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21       -p
22           Preserve relative colors, adjust brightness only
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24       -r
25           Reset to standard color range
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27       --verbose
28           Verbose module output
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30       --quiet
31           Quiet module output
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33   Parameters:
34       red=string
35           LANDSAT red channel
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37       green=string
38           LANDSAT green channel
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40       blue=string
41           LANDSAT blue channel
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43       strength=integer
44           Cropping intensity (upper brightness level)
45           Options: 0-100
46           Default: 98
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DESCRIPTION

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

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

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

82       The strength option requires further refinement.
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AUTHORS

88       Markus Neteler
89       M. Hamish Bowman, Dept. Marine Science, Otago University, New Zealand
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91       Last changed: $Date: 2006-09-07 11:24:10 +0200 (Thu, 07 Sep 2006) $
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93       Full index
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95       © 2003-2008 GRASS Development Team
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99GRASS 6.3.0                                                   i.landsat.rgb(1)