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 generates 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 precision of the JPEG-2000  component  with  the
       greatest  precision.   The  samples in all components 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 .  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

       In  addition  to  the options common to all programs based on libnetpbm (most notably -quiet, see  Common
       Options ), jpeg2ktopam recognizes the following command line 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 the pamtojpeg2k manual(1) for general information on JPEG-2000 compression and the JPEG-2000 formats.

SEE ALSO

       pamtojpeg2k(1), jpegtopnm(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.

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/jpeg2ktopam.html

netpbm documentation                             08 October 2009                      Jpeg2ktopam User Manual(1)