ppmtopgm
convert a portable pixmap into a portable graymap
see also :
pgmtoppm - ppmtorgb3 - rgb3toppm - ppmdist
Synopsis
ppmtopgm
[ppmfile]
add an example, a script, a trick and tips
examples
source
pnmmerge giftopnm < ${fich}.gif | ppmtopgm
| pgmmerge pgmenhance -1 | pnmmerge pnmscale 2 | pgmmerge
pgmtopbm | ppmmerge ppmtogif > ${fich}_d.gif
pnmmerge giftopnm < ${fich}.gif | ppmtopgm
| pgmmerge pgmenhance -1 | pnmmerge pnmscale 2 | pgmmerge
pgmtopbm | ppmmerge ppmtopict > ${fich}_d.pict
source
*PPM* )
ppmtopgm "$file"
exit 0
;;
esac
exit -1
source
pngtopnm $< | pnmscale 4 | pnmconvol
$(srcdir)/../herds/convol11.pnm |\
ppmtopgm | pnmdepth 255 | \
pnmtops -noturn -width 100 -height 100 > $@ || rm -f $@
%.ps: $(srcdir)/../herds/%.png $(srcdir)/../herds/convol5.pnm
pnmconvol $(srcdir)/../herds/convol5.pnm | ppmtopgm |
\
pnmdepth 255 | pnmtops -width 100 -height 100 -noturn >
$@ || rm -f
$@
%.ps: $(srcdir)/../screen/%.png
source
pngtopnm $< | pnmscale 4 | pnmconvol
$(srcdir)/../herds/convol11.pnm |\
ppmtopgm | pnmdepth 255 | \
pnmtops -noturn -width 100 -height 100 > $@ || rm -f $@
%.ps: $(srcdir)/../herds/%.png $(srcdir)/../herds/convol5.pnm
pnmconvol $(srcdir)/../herds/convol5.pnm | ppmtopgm |
\
pnmdepth 255 | pnmtops -width 100 -height 100 -noturn >
$@ || rm -f
$@
%.ps: $(srcdir)/../screen/%.png
description
Reads a
portable pixmap as input. Produces a portable graymap as
output. The output is a "black and white"
rendering of the original image, as in a black and white
photograph. The quantization formula used is .299 r + .587 g
+ .114 b.
Note that
although there is a pgmtoppm program, it is not
necessary for simple conversions from pgm to ppm , because
any ppm program can read pgm (and pbm ) files automatically.
pgmtoppm is for colorizing a pgm file. Also, see
ppmtorgb3 for a different way of converting color to
gray. And ppmdist generates a grayscale image from a
color image, but in a way that makes it easy to
differentiate the original colors, not necessarily a way
that looks like a black and white photograph.
quote
Cold-hearted orb that rules the night
Removes the colors from our sight
Red is gray, and yellow white
But we decide which is right
And which is a quantization error.
see also
pgmtoppm , ppmtorgb3 , rgb3toppm , ppmdist ,ppm,pgm
author
Copyright (C)
1989 by Jef Poskanzer.