r.out.ppmgrass - Online in the Cloud

PROGRAM:

NAME

r.out.ppm - Converts a GRASS raster map to a PPM image file.

KEYWORDS

raster, export

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 instead. 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 differ, 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 transparent 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

Use r.out.ppmgrass online using onworks.net services