Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
Jpeg2ktopam User Manual(0)			    Jpeg2ktopam	User Manual(0)

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

       jpeg2ktopam [-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.

       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

       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_IM-
       AGE_CS_GRAY),  jpeg2ktopam generates a PGM image, unless	the image con-
       tains 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

       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  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.

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

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

	 jpeg2ktopam myimg.jpc >myimg.ppm

       See the pamtojpeg2k manual(1) for general information on	JPEG-2000 com-
       pression	and the	JPEG-2000 formats.

       pamtojpeg2k(1), jpegtopnm(1), ppm(5), pgm(5), pbm(5), pam(5),

       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.

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

netpbm documentation		08 October 2009	    Jpeg2ktopam	User Manual(0)


Want to link to this manual page? Use this URL:

home | help