r.what.color - GRASS manual
Author: GRASS Development Team
Description: r.what.color: Queries colors for a raster map layer.
Keywords: raster, querying, color table

## NAME

r.what.color - Queries colors for a raster map layer.

## KEYWORDS

raster, querying, color table

## SYNOPSIS

r.what.color
r.what.color --help
r.what.color [-i] input=name [value=float[,float,...]] [format=string] color_format=name [--help] [--verbose] [--quiet] [--ui]

### Flags:

-i
  Read values from stdin
--help
  Print usage summary
--verbose
  Verbose module output
--quiet
  Quiet module output
--ui
  Force launching GUI dialog

### Parameters:

input=name [required]
  Name of input raster map
value=float[,float,...]
  Values to query colors for
format=string
  Output format ('plain', 'json', or printf-style string)
  Output format printf-style is deprecated, use 'color_format' option instead.
  Default: %d:%d:%d
color_format=name [required]
  Color format
  Color format for output values. Applies only when format is set to 'plain' or 'json'.
  Options: rgb, hex, hsv, triplet
  Default: hex
  rgb: output color in RGB format
  hex: output color in HEX format
  hsv: output color in HSV format (experimental)
  triplet: output color in colon-separated RGB format

## DESCRIPTION

r.what.color outputs the color associated with user-specified category values in a raster input map.

Values may be specified either using the values= option, or by specifying the -i flag and passing the values on `stdin`, one per line.

For each value which is specified, a line of output will be generated consisting of the category value followed by the color, e.g.:

    r.what.color input=elevation.dem value=1500
    1500: 223:127:31

If the input map is an integer (CELL) map, the category will be written as an integer (no decimal point), otherwise it will be written in floating point format (printf("%.15g") format).

If the lookup fails for a value, the color will be output as an asterisk, e.g.:

    r.what.color input=elevation.dem value=9999
    9999: *

If a value cannot be parsed, both the value and the color will be output as an asterisk, e.g.:

    r.what.color input=elevation.dem value=bogus
    *: *

The format can be changed using the format= option. The value should be a printf()-style format string containing three conversion specifiers for the red, green and blue values respectively, e.g.:

    r.what.color input=elevation.dem value=1500 format='%02x:%02x:%02x'
    1500: df:7f:1f

If your system supports the %m$ syntax, you can change the ordering of the components, e.g.:

    r.what.color input=elevation.dem value=1500 format='%3$02x:%2$02x:%1$02x'
    1500: 1f:7f:df

Common formats:

- Tcl/Tk: `format="#%02x%02x%02x"`
- WxPython: `format='"#%02x%02x%02x"'` or `format='"(%d,%d,%d)"'`

## SEE ALSO

r.what

## AUTHOR

Glynn Clements

## SOURCE CODE

Available at: r.what.color source code (history)

Latest change: Thursday Oct 02 14:39:13 2025 in commit: 1850489bf42c72d8dcfe2e4db1738441b4a7dc43

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