pnmtotiff

 

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 pnmtotiff(1)                                         pnmtotiff(1)
 
 
 
NAME
        pnmtotiff - convert a PNM image to a TIFF file
 
SYNOPSIS
        pnmtotiff   [-none|-packbits|-lzw|-g3|-g4]  [-2d]  [-fill]
        [-predictor  n]  [-msb2lsb|-lsb2msb]   [-rowsperstrip   n]
        [-minisblack] [pnmfile]
 
        Minimum  unambiguous  abbreviations of options are accept­
        able.
 
 
DESCRIPTION
        Reads a PNM image as input.  Produces a TIFF file as  out­
        put.
 
 
OPTIONS
        By default, pnmtotiff creates a TIFF file with no compres­
        sion.  This is your best bet most of  the  time.   If  you
        want  to  try  another compression scheme or tweak some of
        the other even more obscure output options,  there  are  a
        number of flags to play with.
 
        Actually,  the  best  default would be to use LZW compres­
        sion, which is what pnmtotiff used to do by default.  How­
        ever,  the Tiff library no longer does LZW compression due
        to concerns with violating Unisys's patent on LZW compres­
        sion.
 
        The  -none, -packbits, -lzw, -g3, and -g4 options are used
        to override the default and  set  the  compression  scheme
        used  in  creating the output file.  The CCITT Group 3 and
        Group 4 compression  algorithms  can  only  be  used  with
        bilevel  data.   -lzw doesn't really work because the Tiff
        library doesn't do LZW compression.  It used to,  but  its
        developers  removed the function out of concern about vio­
        lating Unisys's patent.  This option remains in  case  you
        use  a Tiff library that cooperates, now or in the future.
        The -2d and -fill options are meaningful only with Group 3
        compression:  -2d  requests  2-dimensional encoding, while
        -fill requests that each encoded scanline  be  zero-filled
        to a byte boundry.  The -predictor option is only meaning­
        ful with LZW compression: a predictor value  of  2  causes
        each  scanline  of  the output image to undergo horizontal
        differencing before it is encoded; a  value  of  1  forces
        each scanline to be encoded without differencing.
 
        By  default, pnmtotiff creates a TIFF file with msb-to-lsb
        fill order.  The -msb2lsb and -lsb2msb options are used to
        override the default and set the fill order used in creat­
        ing the file.
 
        The -rowsperstrip option can be used to set the number  of
        rows (scanlines) in each strip of data in the output file.
        By default, the output file has the  number  of  rows  per
        strip  set  to  a  value that will ensure each strip is no
        more than 8 kilobytes long.
 
        The -minisblack option forces the output image to  have  a
        "minimum  is black" photometric even when using Group 3 or
        Group 4 compression, in which case CCITT fax standards say
        the proper photometric is "minimum is white."
 
        Without  the  -minisblack  option,  pnmtotiff  follows the
        standard.  This usually results in better compression  and
        is generally preferred for bilevel coding.
 
        Before  February  2001, pnmtotiff always produced "minimum
        is black," due to a bug.  In either case,  pnmtotiff  sets
        the  photometric  interpretation  tag  in  the TIFF output
        according to which photometric is actually used.
 
 
NOTES
        There are myriad variations of the TIFF format,  and  this
        program generates only a few of them.  pnmtotiff creates a
        grayscale TIFF file if its input is a PBM (monochrome)  or
        PGM  (grayscale) file.  If the input is a PPM (color) file
        and there are 256 colors or fewer, pnmtotiff  generates  a
        color  palette  TIFF  file.  If there are more colors than
        that, pnmtotiff generates an RGB (not RGBA)  single  plane
        TIFF  file.   Use  pnmtotiffcmyk  to  generate  the  cyan-
        magenta-yellow-black ink color separation TIFF format.
 
SEE ALSO
        tifftopnm(1), pnmtotiffcmyk(1), pnm(5)
 
AUTHOR
        Derived by Jef Poskanzer from ras2tiff.c, which  is  Copy­
        right  (c) 1990 by Sun Microsystems, Inc.  Author: Patrick
        J. Naughton (naughton@wind.sun.com).
 
 
 
                          24 January 2001             pnmtotiff(1)

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