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CPALDJVU(1)			 DjVuLibre-3.5			   CPALDJVU(1)

NAME
       cpaldjvu	- DjVuDocument encoder for low-color images.

SYNOPSIS
       cpaldjvu	 [options] inputppmfile	outputdjvufile

DESCRIPTION
       Program	cpaldjvu  is  a	DjVuDocument encoder for images	containing few
       colors.	It performs best on images containing large solid color	 areas
       such  as	 screen	 dumps.	 Compression ratios on such images can be much
       higher than those achieved by GIF or PNG	compression.

       This program works by first reducing the	number of distinct colors to a
       small specified value using a simple color quantization algorithm.  The
       dominant	color is encoded into the background layer.  The other	colors
       are encoded into	the foreground layer.

OPTIONS
       -dpi n Specify  the resolution information encoded into the output file
	      expressed	in dots	per inch. The resolution  information  encoded
	      in  DjVu	files  determine how the decoder scales	the image on a
	      particular display.  Meaningful resolutions  range  from	25  to
	      6000.  The default value is 300 dpi.

       -colors n
	      Specify  a maximum number	of distinct colors for the color quan-
	      tization algorithm.  process. The	default	value is 256.  Smaller
	      values can produce much smaller files.

       -bgwhite
	      Cause  the background layer to use the lightest quantified color
	      instead of the dominant color.

       -verbose
	      Display informational messages while running.

REMARKS
       The color quantization might introduce severe degradation if the	 image
       contains	photographic areas with	a large	number of very similar colors.
       Color quantization problems might be solved by pre-processing the input
       file with a different quantization program such as ppmquant.  Avoid us-
       ing the error diffusion dithering algorithm.  This algorithm  generates
       random dithering	patterns that might be very costly to encode.

BUGS
       This program should be rewritten	as a pre-processor for csepdjvu.

CREDITS
       This  program was initially written by Leon Bottou <leonb@users.source-
       forge.net> and was improved by Bill  Riemers  <docbill@sourceforge.net>
       and many	others.

SEE ALSO
       djvu(1),	pbm(5),	ppmquant(1), pnmtogif(1), pnmtopng(1)

DjVuLibre-3.5			  10/11/2001			   CPALDJVU(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | REMARKS | BUGS | CREDITS | SEE ALSO

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