NAME

       r.rescale  - Rescales the range of category values in a raster map layer.

KEYWORDS

       raster, rescale

SYNOPSIS

       r.rescale
       r.rescale help
       r.rescale  [-q]  input=string  [from=min,max]  output=string to=min,max  [title="phrase"]   [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       -q
           Quietly

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=string
           The name of the raster map to be rescaled

       from=min,max
           The input data range to be rescaled (default: full range of input map)

       output=string
           The resulting raster map name

       to=min,max
           The output data range

       title=
           Title for new raster map

DESCRIPTION

       The r.rescale program rescales the range of category values appearing in  a  raster  map  layer.   A  new
       raster  map  layer,  and  an appropriate category file and color table based upon the original raster map
       layer, are generated with category labels that reflect the original category values  that  produced  each
       category.   This command is useful for producing representations with a reduced number of categories from
       a raster map layer with a large range of category values (e.g.,  elevation).   Rescaled  map  layers  are
       appropriate for use in such GRASS programs as r.stats, r.report, and r.coin.

EXAMPLE

       To  rescale  an  elevation  raster map layer with category values ranging from 1090 meters to 1800 meters
       into the range 0-255, the following command line could be used (without  the  from  parameter,  the  full
       value range will be used):
       r.rescale input=elevation from=1090,1800 output=elevation.255 to=0,255

NOTES

       Category  values  that  fall  beyond  the input range will become NULL.  This allows the user to select a
       subset of the full category value range for rescaling if desired.  This also means that the  user  should
       know the category value range for the input raster map layer.  The user can request the r.rescale program
       to  determine  this  range,  or  can  obtain it using the r.info command.  If the category value range is
       determined using r.rescale, the input raster map layer is examined, and the minimum and maximum  non-NULL
       category values are selected as the input range.

SEE ALSO

       r.coin, r.describe, r.info, r.mapcalc, r.reclass, r.rescale.eq, r.report, r.resample, r.stats

AUTHOR

       Michael Shapiro, U.S.Army Construction Engineering Research Laboratory

       Last changed: $Date: 2010-10-06 09:11:45 -0700 (Wed, 06 Oct 2010) $

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       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                                    r.rescale(1grass)