ppmtosixel - convert a portable pixmap into DEC sixel format
ppmtosixel [__-raw__? [__-margin__?
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.
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
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.
Generally, sixel files must reach the printer unfiltered.
Use the lpr -x option or cat filename
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.
Copyright (C) 1991 by Rick Vinci.