NAME
r.out.ppm - Converts a GRASS raster file to a PPM image file at the pixel resolution of the CURRENTLY DEFINED REGION.
SYNOPSIS
r.out.ppm
r.out.ppm help
r.out.ppm [-qG] input=string [output=string]
Flags:
- -q
- Run quietly
- -G
- Output greyscale instead of color
Parameters:
- input=string
- Raster file to be converted.
- output=string
- Name for new PPM file. (use out=- for stdout)
- Default: .ppm
DESCRIPTION
r.out.ppm converts a GRASS raster file to a PPM image file
at the pixel resolution of the CURRENTLY DEFINED REGION.
To get the resolution and regions settings of the raster map, run:
g.region rast=[mapname]
before running r.out.ppm.
The PPM file created is 24bit color, rawbits storage by default.
Using -G, you may force r.out.ppm to use 8bit 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.
NOTE
A few ppm file comments are written - the name of the GRASS
raster file, 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.)
TODO
Allow combination of 3 grass files to represent R, G, B components of ppm file?
SEE ALSO
r.out.ascii,
r.out.ppm3,
r.out.tiff
AUTHOR
Bill Brown, UIUC
Last changed: $Date: 2003/05/06 14:33:56 $
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