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r.out.ppm

Converts a GRASS raster map to a PPM image file.

r.out.ppm [-gh] input=name [output=name] [--overwrite] [--verbose] [--quiet] [--qq] [--ui]

Example:

r.out.ppm input=name

grass.script.run_command("r.out.ppm", input, output="<rasterfilename>.ppm", flags=None, overwrite=False, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("r.out.ppm", input="name")

Parameters

input=name [required]
    Name of input raster map
output=name
    Name for new PPM file (use '-' for stdout)
    Default: <rasterfilename>.ppm
-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
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

input : str, required
    Name of input raster map
    Used as: input, raster, name
output : str, optional
    Name for new PPM file (use '-' for stdout)
    Used as: output, file, name
    Default: <rasterfilename>.ppm
flags : str, optional
    Allowed values: g, h
    g
        Output greyscale instead of color
    h
        Suppress printing of PPM header
overwrite: bool, optional
    Allow output files to overwrite existing files
    Default: False
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

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

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)
Latest change: Friday Feb 07 19:16:09 2025 in commit a82a39f