Manual: jpeg2ktopam

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 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, un‐
       less 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").	 Ac‐
       tually,	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 for‐
       mats.   Because	it's  packaged with the library, it may exploit it better, especially recently added features.	How‐
       ever, 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)