r.out.ppm(1grass) GRASS GIS User's Manual r.out.ppm(1grass)
NAME
r.out.ppm - Converts a GRASS raster map to a PPM image file.
KEYWORDS
raster, export, output
SYNOPSIS
r.out.ppm
r.out.ppm --help
r.out.ppm [-gh] input=name [output=name] [--overwrite] [--help]
[--verbose] [--quiet] [--ui]
Flags:
-g
Output greyscale instead of color
-h
Suppress printing of PPM header
--overwrite
Allow output files to overwrite existing files
--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
output=name
Name for new PPM file (use ’-’ for stdout)
Default: <rasterfilename>.ppm
DESCRIPTION
r.out.ppm converts a GRASS raster map into a PPM image at the pixel
resolution of the CURRENTLY DEFINED REGION. To get the resolution and
region settings of the raster map, run:
g.region -p raster=[mapname]
before running r.out.ppm.
By default the PPM file created is 24-bit color, rawbits storage. You
can use the -g flag to force r.out.ppm to output an 8-bit greyscale in-
stead. The greyscale conversion uses the NTSC conversion:
Y = .30*Red + .59*Green + .11*Blue
One pixel is written for each cell value, so if ew_res and ns_res dif-
fer, the aspect ratio of the resulting image will be off.
NOTES
A few ppm file comments are written: the name of the GRASS raster map,
resolution, etc. Although these are perfectly legal, I’ve found one PD
image utility that chokes on them, so if you need a commentless PPM
file, use ’out=- > outfile.ppm’. (When sending output to stdout, no
comments are written.)
HINTS
You can create a PNG image with NULL values represented by a transpar-
ent background by using the PNG driver with GRASS_RENDER_TRANSPARENT
set to TRUE. Alternatively, you can use the pnmtopng program from
netpbm to do this:
r.out.ppm raster
pnmtopng -transparent white raster.ppm > raster.png
SEE ALSO
d.out.file, r.out.ascii, r.out.gdal, r.out.mpeg, r.out.png, r.out.ppm3
AUTHOR
Bill Brown, UIUC
SOURCE CODE
Available at: r.out.ppm source code (history)
Accessed: unknown
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GRASS 7.8.7 r.out.ppm(1grass)
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