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Pamtojpeg2k User Manual(0)			    Pamtojpeg2k	User Manual(0)

NAME
       pamtojpeg2k - convert PAM/PNM image to a	JPEG-2000 code stream

SYNOPSIS
       pamtojpeg2k [-imgareatlx=column]	[-imgareatly=row] [-tilegrdtlx=column]
       [-tilegrdtly=row]	[-tilewidth=columns]	    [-tileheight=rows]
       [-prcwidth=columns]	  [-prcheight=rows]	  [-cblkwidth=columns]
       [-cblkheight=rows]   [-mode={integer|int|real}]	  [-compression=ratio]
       [-ilyrrates=ratestring]		[-numrlvls=number]	    [-progres-
       sion={lrcp|rlcp|rpcl|pcrl|cprl}]	 [-numgbits=number]  [-nomct]	[-sop]
       [-eph]  [-lazy]	[-termall]  [-segsym] [-vcausal] [-pterm] [-resetprob]
       [-verbose] [-debuglevel=number] filename

       Minimum unique abbreviation of option is	acceptable.  You may use  dou-
       ble  hyphens  instead  of single	hyphen to denote options.  You may use
       white space in place of the equals sign to separate an option name from
       its value.

DESCRIPTION
       This program is part of Netpbm(1).

       pamtojpeg2k  converts the named PBM, PGM, PPM, or PAM file, or Standard
       Input if	no file	is named, to a JPEG-2000 code  stream  (JPC)  file  on
       Standard	Output.

       The  JPEG-2000  specification  specifies	 two separate formats: JP2 and
       JPEG-2000 code stream (JPC).   JP2  represents  a  visual  image	 quite
       specifically,  whereas  JPC is a	more or	less arbitrary array of	codes.
       pamtojpeg2k can't produce a JP2,	but the	 JPC  image  that  pamtojpeg2k
       produces	 is  very  similar to a	JP2 if the input is a PBM, PGM,	or PPM
       image or	equivalent PAM image.  One difference is that the  RGB	inten-
       sity  values in a JP2 are SRGB values, while pamtojpeg2k	produces ITU-R
       Recommendation BT.709 values.  Those are	very similar, but not  identi-
       cal.   Another  difference  is that a JP2 can contain extra information
       about an	image that JPC cannot.

       When the	input is a PAM image other than	a PBM, PGM, or PPM equivalent,
       the  JPC	raster produced	contains whatever the PAM raster does.	It can
       have any	number of planes with any meanings; the	planes are in the same
       order in	the JPC	output as in the PAM input.

       A  JPC  image  has  a "precision," which	is the number of bits used for
       each code (in Netpbm lingo, "sample").  Actually,  it  has  a  separate
       precision  for  each  component.	 pamtojpeg2k uses for the precision of
       every component the least number	of bits	that can represent the	maxval
       of  the	input image.  A	JPC image does not have	an independent concept
       of maxval; the maxval of	a JPC sample is	the  maximum  value  that  the
       number  of bits specified by the	precision can represent	in pure	binary
       code.  E.g. if the precision is 4, the maxval is	15.  pamtojpeg2k  does
       of  course  scale the sample values from	the input maxval to the	output
       maxval.	Example: The input maxval is 99.  This means JPC precision  is
       7  bits	and  the JPC maxval is 127.  A sample value of 33 in the input
       becomes a sample	value of 43 in the output.

       pamtojpeg2k generates the JPC output with the Jasper JPEG-2000  library
       <http://www.ece.uvic.ca/~mdadams/jasper/>  .   See documentation	of the
       library for details on what pamtojpeg2k produces.  Note that the	Jasper
       library	contains  facilities  for  reading PNM images, but pamtojpeg2k
       does not	use those.  It uses the	Netpbm library instead.	 Note that the
       makers  of  the Jasper library write it "JasPer," but Netpbm documenta-
       tion follows standard American English typography  rules,  which	 don't
       allow that kind of capitalization.

       Use jpeg2ktopam to convert in the other direction.

       The  program  jasper,  which  is	packaged with the Jasper JPEG-2000 li-
       brary, also converts between JPEG-2000 and PNM formats.	 Because  it's
       packaged	 with  the  library,  it may exploit it	better,	especially re-
       cently added features.  However,	since it does not use the  Netpbm  li-
       brary to	read and write the Netpbm formats, it doesn't do as good a job
       on that side.

       Another format with goals similar to those of JPEG-2000 but that	allows
       for    faster	encoding    and	   decoding,   is   JPEG-LS.	CharLS
       <http://charls.codeplex.com>  is	a package of software for using	 JPEG-
       LS.

OPTIONS
       Most  of	the options are	identical in name and function to options that
       the  Jasper  library  JPC  encoder  subroutine	takes.	  See	Jasper
       documentation  <http://www.ece.uvic.ca/~mdadams/jasper/>	  for details.
       Here, we	document only options that are not direct  analogs  of	Jasper
       options.

       -compression=ratio
	      ratio  is	a floating point number	that specifies the compression
	      ratio.  pamtojpeg2k will adjust quality as necessary  to	ensure
	      that  you	 get  this compression ratio.  E.g. 4 means the	output
	      will be about one	fourth the size	in bytes of the	input file.

	      The ratio	concerns just the raster part of the image,  with  the
	      denominator  being what the raster would take if it were encoded
	      the most naive way possible (e.g.	3 bytes	per  pixel  in	8-bit-
	      per-sample  RGB).	  It  does,  however, include metadata that is
	      part of the compressed raster.  Because of that, it may  not  be
	      possible	to  give  you  your requested compression ratio	at any
	      quality.	If it isn't, pamtojpeg2k fails with a  message	saying
	      so.

	      If you don't specify this	option,	pamtojpeg2k gives you the best
	      compression it can without losing	any quality.  Because  of  the
	      metadata	issue  described above,	this may mean, for a small im-
	      age, the image actually expands.

	      Note that	though the Jasper library takes	a compression  factor,
	      this option specifies a compression ratio.  The compression fac-
	      tor is the multiplicative	inverse	of (1 divided by) the compres-
	      sion ratio.

	      Before  Netpbm 10.61 (December 2012), the	default	was a compres-
	      sion ratio of 1, and if pamtojpeg2k could	not  make  the	output
	      that  small,  it	just  made  it as small	as it could, with zero
	      quality.	You know this is happening when	you  see  the  warning
	      message, "empty layer generated."

       -verbose
	      This  option  causes pamtojpeg2k to issue	informational messages
	      about the	conversion process.

       -debuglevel=number
	      This option controls debug messages  from	 the  Jasper  library.
	      pamtojpeg2k  passes  number as the debug level to	the Jasper JPC
	      encoder.

EXAMPLES
       This example compresses losslessly.

	 pamtojpeg2k myimg.ppm >myimg.jpc

       jpeg2ktopam will	recreate myimg.ppm exactly.

       This example compresses the file	to one tenth its original size,	throw-
       ing away	information as necessary.

	 pamtojpeg2k -compression=10 myimg.pgm >myimg.jpc

ABOUT JPEG-2000
       JPEG-2000  is a format that compresses a	visual image (or a similar set
       of data)	into a minimal number of bytes for  storage  or	 transmission.
       In that,	its goal is similar to JPEG.  It has two main differences from
       JPEG.

       One difference is that it does a	much better  job  on  most  images  of
       throwing	 out  information  in order to achieve a smaller output.  That
       means when you reconstruct the  image  from  the	 resulting  compressed
       file,  it  looks	 a  lot	closer to the image you	started	with JPEG-2000
       than with JPEG, for the same compressed file size.  Or, looked  at  an-
       other  way,  with  JPEG-2000 you	get a much smaller file	than with JPEG
       for the same image quality.

       The second difference is	that with JPEG-2000, you decide	how much  com-
       pression	 you  want and the compressor adjusts the quality to meet your
       requirement, whereas with JPEG, you decide how much  quality  you  want
       and the compressor adjusts the size of the output to meet your require-
       ment.  I.e. with	JPEG-2000, the quality of the result  depends  on  the
       compressibility of the input, but with JPEG, the	size of	the result de-
       pends on	the compressibility of the input.

       With JPEG-2000, you can specify lossless	compression,  thus  making  it
       compete	with  GIF  and PNG.  With standard JPEG, you always lose some-
       thing.  (There are rumored to be	variations of  JPEG  around  that  are
       lossless, though).

       JPEG is much older than JPEG-2000 and far more popular.	JPEG is	one of
       the half	dozen most popular graphics formats and	virtually all graphics
       facilities understand it.  JPEG-2000 is virtually unknown.

       There  is  no  compatibility between JPEG and JPEG-2000.	 Programs that
       read JPEG do not	automatically read JPEG-2000 and vice versa.

SEE ALSO
       jpeg2ktopam(1), pnmtojpeg(1), ppm(5), pgm(5), pbm(5), pam(5),

History
       pamtojpeg2k was added to	Netpbm in Release 10.12	(November 2002).

DOCUMENT SOURCE
       This manual page	was generated by the Netpbm tool 'makeman'  from  HTML
       source.	The master documentation is at

	      http://netpbm.sourceforge.net/doc/pamtojpeg2k.html

netpbm documentation		31 January 2014	    Pamtojpeg2k	User Manual(0)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | ABOUT JPEG-2000 | SEE ALSO | History | DOCUMENT SOURCE

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