NAME¶
r.out.ppm - Converts a GRASS raster map to a PPM image file at the
pixel resolution of the currently defined region.
KEYWORDS¶
raster, export
SYNOPSIS¶
r.out.ppm
r.out.ppm help
r.out.ppm [-
qG]
input=
name
[
output=
name] [--
verbose] [--
quiet]
Flags:¶
- -q
-
Run quietly
- -G
-
Output greyscale instead of color
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- input=name
-
Name of input raster map
- output=name
-
Name for new PPM file (use '-' for stdout)
Default: .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 rast=[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_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.png
r.out.ascii
r.out.mpeg
r.out.png
r.out.ppm3
r.out.tiff
AUTHOR¶
Bill Brown, UIUC
Last changed: $Date: 2008-05-16 21:09:06 +0200 (Fri, 16 May 2008) $
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