ppmtosixel
convert a portable pixmap into DEC sixel format
Synopsis
ppmtosixel
[-raw] [-margin] [ppmfile]
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examples
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description
Reads a
portable pixmap as input. Produces sixel commands (SIX) as
output. The output is formatted for color printing, e.g. for
a DEC LJ250 color inkjet printer.
If RGB values
from the PPM file do not have maxval=100, the RGB values are
rescaled. A printer control header and a color assignment
table begin the SIX file. Image data is written in a
compressed format by default. A printer control footer ends
the image file.
options
-raw
If specified, each pixel will be
explicitly described in the image file. If -raw is
not specified, output will default to compressed format in
which identical adjacent pixels are replaced by "repeat
pixel" commands. A raw file is often an order of
magnitude larger than a compressed file and prints much
slower.
-margin
If -margin is not
specified, the image will be start at the left margin (of
the window, paper, or whatever). If -margin is
specified, a 1.5 inch left margin will offset the image.
printing
Generally, sixel files must reach the printer unfiltered. Use the
lpr -x option or cat filename > /dev/tty0?.
bugs
Upon rescaling,
truncation of the least significant bits of RGB values may
result in poor color conversion. If the original PPM maxval
was greater than 100, rescaling also reduces the image
depth. While the actual RGB values from the ppm file are
more or less retained, the color palette of the LJ250 may
not match the colors on your screen. This seems to be a
printer limitation.
see also
ppm
author
Copyright (C)
1991 by Rick Vinci.