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Jpeg2ktopam User Manual(0)					       Jpeg2ktopam User Manual(0)

NAME
       jpeg2ktopam - convert JPEG-2000 code stream to PAM/PNM

SYNOPSIS
       jpeg2ktopam [-verbose] [-debuglevel=number] filename

OPTION USAGE
       Minimum	unique	abbreviation of option is acceptable.  You may use double 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)

       jpeg2ktopam  converts  the named JPEG-2000 file (JP2 or JPC), or Standard Input if no file
       is named, to a PBM, PGM, PPM, or PAM file on Standard Output.

       The JPEG-2000 specification specifies two different 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.  A JP2 image contains a JPC stream and metadata  describing  how
       that stream represents a visual image.  jpeg2ktopam converts both.

       If  the	color space identified in the image is grayscale (JAS_IMAGE_CS_GRAY), jpeg2ktopam
       generates a PGM image, unless the image contains only one bit per  pixel,  in  which  case
       jpeg2ktopam generates PBM.  If the color space is RGB (JAS_IMAGE_CS_RGB), jpeg2ktopam gen-
       erates a PPM image.  If the input image is anything  else,  jpeg2ktopam	generates  a  PAM
       image with no tuple type identified.

       In the PGM and PPM cases, jpeg2ktopam assumes the intensity values in the input image have
       the same meaning as for PGM and PPM.  One thing that implies is the  ITU-R  Recommendation
       BT.709  color  space,  which  means the assumption is false for JP2 input.  JP2 input uses
       SRGB color encoding.  So if you use jpeg2ktopam to convert a JP2 image to PPM, it  changes
       the visual image (slightly) -- the colors in the output are not the same as in the input.

       In  the	PAM image, the output samples are numerically identical to the input samples.  If
       the input samples are signed, they are represented in two's complement form in the  output
       (because PAM samples are always unsigned).  The PAM plane numbers are identical to the JPC
       component numbers.

       A JPEG-2000 image has a "precision," which is the number of bits used for  each	code  (in
       Netpbm  lingo,  "sample").  Actually, each component has a separate precision.  The maxval
       of a PGM, PPM, or PAM output is the largest number you can represent in the JPEG-2000 pre-
       cision  of the JPEG-2000 component with the greatest precision.	The samples in all compo-
       nents are scaled to that maxval.  So if the red component has a precision of  4	bits  and
       the  green  component  has  a  precision of 6 bits, the maxval is 63 and the red component
       codes from the JPEG-2000 image are multiplied by 63/15 to generate the output samples.

       jpeg2ktopam  interprets	the  JPEG-2000	input	with   the   Jasper   JPEG-2000   library
       <http://www.ece.uvic.ca/~mdadams/jasper/>  .  See documentation of the library for details
       on what jpeg2ktopam handles.  Note that the Jasper library contains facilities for writing
       PNM images, but jpeg2ktopam does not use those.	It uses the Netpbm library instead.  Note
       that the makers of the Jasper library write it "JasPer," but Netpbm documentation  follows
       standard American English typography rules, which don't allow that kind of capitalization.

       Use pamtojpeg2k to convert in the other direction.

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

OPTIONS
       -verbose
	      This option causes jpeg2ktopam to issue informational messages about the conversion
	      process.

       -debuglevel=number
	      This  option  controls  debug messages from the Jasper library.  jpeg2ktopam passes
	      number as the debug level to the Jasper JPEG-2000 decoder.

EXAMPLES
	 jpeg2ktopam myimg.jpc >myimg.ppm

ABOUT JPEG-2000
       See thepamtojpeg2kmanual(1)

       for general information on JPEG-2000 compression and the JPEG-2000 formats.

SEE ALSO
       pamtojpeg2k(1) , pnmtopeg(1) , ppm(1) , pgm(1) , pbm(1) , pam(1) ,

History
       jpeg2ktopam was added to Netpbm in Release 10.12 (November 2002).

       Before Netpbm 10.49 (December 2009), jpeg2ktopam could not convert a JP2 file -- only JPC.

netpbm documentation			 08 October 2009	       Jpeg2ktopam User Manual(0)
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