1i.colors.enhance(1)           Grass User's Manual          i.colors.enhance(1)
2
3
4

NAME

6       i.colors.enhance  - Performs auto-balancing of colors for RGB images.
7

KEYWORDS

9       imagery, RGB, satellite, colors
10

SYNOPSIS

12       i.colors.enhance
13       i.colors.enhance --help
14       i.colors.enhance      [-fprs]     red=name     green=name     blue=name
15       [strength=float]   [--help]  [--verbose]  [--quiet]  [--ui]
16
17   Flags:
18       -f
19           Extend colors to full range of data on each channel
20
21       -p
22           Preserve relative colors, adjust brightness only
23
24       -r
25           Reset to standard color range
26
27       -s
28           Process bands serially (default: run in parallel)
29
30       --help
31           Print usage summary
32
33       --verbose
34           Verbose module output
35
36       --quiet
37           Quiet module output
38
39       --ui
40           Force launching GUI dialog
41
42   Parameters:
43       red=name [required]
44           Name of red channel
45
46       green=name [required]
47           Name of green channel
48
49       blue=name [required]
50           Name of blue channel
51
52       strength=float
53           Cropping intensity (upper brightness level)
54           Options: 0-100
55           Default: 98
56

DESCRIPTION

58       i.colors.enhance auto-balances and enhances the color channels of a RGB
59       image (e.g. from Landsat) to provide a more natural color mixture. Only
60       the color table of each image band is modified, the base  data  remains
61       untouched.
62
63       The  module works by calculating a histogram for each color channel and
64       removing an adjustable amount of outliers from either end before recal‐
65       ibrating the color scale with r.colors.
66
67       It  will  work  with any 8-bit RGB imagery set and the script is easily
68       modified to work with other datasets of greater band-depth.
69

NOTES

71       Depending on the image, it may or may not be advantageous to use the -p
72       flag  to  preserve the relative color scaling. You will have to experi‐
73       ment with the different options to find a setting that works  best  for
74       your particular imagery.
75
76       The  strength  option  should  generally be set in the 90-99 range. The
77       lower the number, the more saturated the image becomes.  It  represents
78       the  percentage  cut-off  for the top end of the color histogram curve.
79       The lower end is fixed at 2% of the area under the curve.
80
81       For quicker execution of this module on large images  you  can  achieve
82       largely similar results by switching to a coarser resolution before the
83       running of the module (using g.region) and then back  to  the  original
84       resolution afterwards.
85

EXAMPLE

87       North Carolina sample dataset example with Landsat data:
88       g.region raster=lsat7_2002_10 -p
89       d.rgb blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30
90       d.barscale at=55.3125,93.125 bcolor=white text_pos=over
91       i.colors.enhance blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30 strength=95
92       d.rgb blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30
93       d.barscale at=55.3125,93.125 bcolor=white text_pos=over
94       Uncorrected RGB composite of Landsat ETM channels B/G/R
95
96       Color corrected RGB composite of Landsat ETM channels B/G/R
97

TODO

99       The strength option requires further refinement.
100

SEE ALSO

102        d.rgb, g.region, i.oif, r.colors, r.composite, r.univar
103

AUTHORS

105       Markus Neteler, Trento, Italy
106       M. Hamish Bowman, Dept. Marine Science, Otago University, New Zealand
107
108       Last changed: $Date: 2018-03-04 13:06:43 +0100 (Sun, 04 Mar 2018) $
109

SOURCE CODE

111       Available at: i.colors.enhance source code (history)
112
113       Main  index | Imagery index | Topics index | Keywords index | Graphical
114       index | Full index
115
116       © 2003-2019 GRASS Development Team, GRASS GIS 7.4.4 Reference Manual
117
118
119
120GRASS 7.4.4                                                i.colors.enhance(1)
Impressum