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RedHat 9 (Linux i386) - man page for pnmtotiff (redhat section 1)

pnmtotiff(1)			     General Commands Manual			     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] [-truecolor] [-color] [pnmfile]

       Minimum unambiguous abbreviations of options are acceptable.

DESCRIPTION
       Reads a PNM image as input.  Produces a TIFF file as output.

       The output goes to Standard Output, which must be a seekable file.  That means  no  pipes,
       but any regular file should work.

OPTIONS
       By default, pnmtotiff creates a TIFF file with no compression.  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 compression, which is what pnmtotiff used
       to do by default.  However, the Tiff library no longer does LZW compression  due  to  con-
       cerns with violating Unisys's patent on LZW compression.

       The  -none, -packbits, -lzw, -g3, -g4, -flate, and -adobeflat 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 violating 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-dimen-
       sional encoding, while -fill requests that each encoded scanline be zero-filled to a  byte
       boundry.  The -predictor option is only meaningful 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  creating
       the file.

       The  fill order is the order in which pixels are packed into a byte in the Tiff raster, in
       the case that there are multiple pixels per byte.  msb-to-lsb means that the leftmost col-
       umns  go  into the most significant bits of the byte in the Tiff image.	However, there is
       considerable confusion about the meaning of fill order.	Some believe it means whether  16
       bit  sample  values  in	the  Tiff image are little-endian or big-endian.  This is totally
       erroneous (The endianness of integers in a Tiff image is designated by the  image's  magic
       number).   However,  ImageMagick  and  older Netpbm both have been known to implement that
       interpretation.	2001.09.06.

       If the image does not have sub-byte pixels, these options have no effect other than to set
       the  value  of the FILLORDER tag in the Tiff image (which may be useful for those programs
       that misinterpret the tag with reference to 16 bit samples).

       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  accord-
       ing to which photometric is actually used.

       -truecolor  tells pnmtotiff to produce the 24-bit RGB form of TIFF output if it is produc-
       ing a color TIFF image.	Without this option, pnmtotiff produces a colormapped  (paletted)
       8-bit  TIFF  image unless there are more than 256 colors (and in the latter case, issues a
       warning).

       The -truecolor option can prevent pnmtotiff from making two passes through the input file,
       thus improving speed and memory usage.  See the section MULTIPLE PASSES.

       If pnmtotiff produces a grayscale TIFF image, this option has no effect.

       -color  tells  pnmtotiff  to  produce  a color, as opposed to grayscale, TIFF image if the
       input is PPM, even if it contains only shades of gray.	Without  this  option,	pnmtotiff
       produces  a grayscale TIFF image if the input is PPM and contains only shades of gray, and
       at most 256 shades.  Otherwise, it produces a color TIFF output.  For PBM and  PGM  input,
       pnmtotiff always produces grayscale TIFF output and this option has no effect.

       The  -color  option  can  prevent pnmtotiff from making two passes through the input file,
       thus improving speed and memory usage.  See the section MULTIPLE PASSES.

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.  pnmtotiff also creates a grayscale file if it input is PPM (color), but
       there  is  only	one color in the image.  If the input is a PPM (color) file and there are
       256 colors or fewer, but more than 1, 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.

       The  number  of	bits per sample in the TIFF output is determined by the maxval of the PNM
       input.  If the maxval is less than 256, the bits per sample in the output is the  smallest
       number  that  can encode the maxval.  If the maxval is greater than or equal to 256, there
       are 16 bits per sample in the output.

   Multiple Passes
       pnmtotiff reads the input image once if it can, and otherwise twice.  It needs that second
       pass  to analyze the colors in the image and generate a color map (pallette) and determine
       if the image is grayscale.  So the second pass only happens when the input  is  PPM.   And
       you can avoid it then by specifying both the -truecolor and -color options.

       If  the input image is small enough to fit in your system's file cache, the second pass is
       very fast.  If not, it requires reading from disk twice, which can be slow.

       When the input is from a file that cannot be  rewound  and  reread,  pnmtotiff  reads  the
       entire  input image into a temporary file which can, and works from that.  Even if it only
       needs one pass.

SEE ALSO
       tifftopnm(1), pnmtotiffcmyk(1), pnmdepth(1), pnm(5)

AUTHOR
       Derived by Jef Poskanzer from ras2tiff.c, which is Copyright (c) 1990 by Sun Microsystems,
       Inc.  Author: Patrick J. Naughton (naughton@wind.sun.com).

					 24 January 2001			     pnmtotiff(1)


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