man > jpeg2ktopam(1)

Jpeg2ktopam User Manual(1)             General Commands Manual            Jpeg2ktopam User Manual(1)

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 sep‐
       arate 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 arbi‐
       trary 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 gen‐
       erates  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  gener‐
       ates  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 vi‐
       sual 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 (be‐
       cause PAM samples are always unsigned).  The PAM plane numbers are identical to the JPC  com‐
       ponent 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 com‐
       ponent 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 ]8;;http://www.ece.uvic.ca/~mdadams/jasper/\Jasper JPEG-2000 library]8;;\ .  See documen‐
       tation 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  be‐
       tween  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  li‐
       brary 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 ]8;;index.html#commonoptions\ Common Options]8;;\ ), 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 num‐
              ber 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)