ppmtopj(1) General Commands Manual ppmtopj(1)NAME
ppmtopj - convert a portable pixmap to an HP PaintJet file
SYNOPSIS
ppmtopj [-gamma val] [-xpos val] [-ypos val] [-back dark|lite] [-rle] [-center] [-render none|snap|bw|dither|diffuse|monodither|monodif-
fuse|clusterdither|monoclusterdither] [ppmfile]
DESCRIPTION
Reads a portable pixmap as input and converts it into a format suitable to be printed by an HP PaintJet printer.
For best results, the input file should be in 8-color RGB form; i.e. it should have only the 8 binary combinations of full-on and full-off
primaries. You could get this by sending the input file through ppmquant -map with a map file such as:
P3
8 1
255
0 0 0 255 0 0 0 255 0 0 0 255
255 255 0 255 0 255 0 255 255 255 255 255
Or else you could use use ppmdither -red 2 -green 2 -blue 2.
OPTIONS -rle Run length encode the image. (This can result in larger images)
-back Enhance the foreground by indicating if the background is light or dark compated to the foreground.
-render alg Use an internal rendering algorithm (default dither).
-gamma int Gamma correct the image using the integet parameter as a gamma (default 0).
-center Center the image to an 8.5 by 11 page
-xpos pos Move by pos pixels in the x direction.
-ypos pos Move by pos pixels in the y direction.
REFERENCES
HP PaintJet XL Color Graphics Printer User's Guide
SEE ALSO pnmdepth(1), ppmquant(1), ppmdither(1), ppm(5)BUGS
Most of the options have not been tested because of the price of the paper.
AUTHOR
Copyright (C) 1991 by Christos Zoulas.
13 July 1991 ppmtopj(1)
Check Out this Related Man Page
ppmquant(1) General Commands Manual ppmquant(1)NAME
ppmquant - quantize the colors in a portable pixmap down to a specified number
SYNOPSIS
ppmquant [-floyd|-fs] ncolors [ppmfile]
ppmquant [-floyd|-fs] [-nofloyd|-nofs] -mapfile mapfile [ppmfile]
All options can be abbreviated to their shortest unique prefix. You may use two hyphens instead of one to designate an option. You may
use either white space or equals signs between an option name and its value.
DESCRIPTION
pnmquant is a newer, more general program that is backward compatible with ppmquant. ppmquant may be faster, though.
Reads a PPM image as input. Chooses ncolors colors to best represent the image, maps the existing colors to the new ones, and writes a PPM
image as output.
The quantization method is Heckbert's "median cut".
Alternately, you can skip the color-choosing step by specifying your own set of colors with the -mapfile option. The mapfile is just a ppm
file; it can be any shape, all that matters is the colors in it. For instance, to quantize down to the 8-color IBM TTL color set, you
might use:
P3
8 1
255
0 0 0
255 0 0
0 255 0
0 0 255
255 255 0
255 0 255
0 255 255
255 255 255
If you want to quantize one image to use the colors in another one, just use the second one as the mapfile. You don't have to reduce it
down to only one pixel of each color, just use it as is.
If you use a mapfile, the output image has the same maxval as the mapfile. Otherwise, the output maxval is the same as the input maxval,
or less in some cases where the quantization process reduces the necessary resolution.
The -floyd/-fs option enables a Floyd-Steinberg error diffusion step. Floyd-Steinberg gives vastly better results on images where the
unmodified quantization has banding or other artifacts, especially when going to a small number of colors such as the above IBM set. How-
ever, it does take substantially more CPU time, so the default is off.
-nofloyd/-nofs means not to use the Floyd-Steinberg error diffusion. This is the default.
REFERENCES
"Color Image Quantization for Frame Buffer Display" by Paul Heckbert, SIGGRAPH '82 Proceedings, page 297.
SEE ALSO pnmquant(1), ppmquantall(1), pnmdepth(1), ppmdither(1), ppm(5)AUTHOR
Copyright (C) 1989, 1991 by Jef Poskanzer.
12 January 1991 ppmquant(1)