1Jpeg2ktopam User Manual(0)                          Jpeg2ktopam User Manual(0)
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NAME

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

10       jpeg2ktopam [-verbose] [-debuglevel=number] filename
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OPTION USAGE

14       Minimum  unique abbreviation of option is acceptable.  You may use dou‐
15       ble hyphens instead of single hyphen to denote options.   You  may  use
16       white space in place of the equals sign to separate an option name from
17       its value.
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DESCRIPTION

21       This program is part of Netpbm(1).
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23       jpeg2ktopam converts the named JPEG-2000 file (JP2 or JPC), or Standard
24       Input  if no file is named, to a PBM, PGM, PPM, or PAM file on Standard
25       Output.
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27       The JPEG-2000 specification specifies two different  formats:  JP2  and
28       JPEG-2000  code  stream  (JPC).   JP2  represents  a visual image quite
29       specifically, whereas JPC is a more or less arbitrary array  of  codes.
30       A  JP2  image  contains  a  JPC stream and metadata describing how that
31       stream represents a visual image.  jpeg2ktopam converts both.
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33       If the color space  identified  in  the  image  is  grayscale  (JAS_IM‐
34       AGE_CS_GRAY),  jpeg2ktopam generates a PGM image, unless the image con‐
35       tains only one bit per pixel, in which case jpeg2ktopam generates  PBM.
36       If  the  color space is RGB (JAS_IMAGE_CS_RGB), jpeg2ktopam generates a
37       PPM image.  If the input image is anything else, jpeg2ktopam  generates
38       a PAM image with no tuple type identified.
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40       In  the  PGM and PPM cases, jpeg2ktopam assumes the intensity values in
41       the input image have the same meaning as for PGM and  PPM.   One  thing
42       that  implies  is  the  ITU-R  Recommendation BT.709 color space, which
43       means the assumption is false for JP2 input.  JP2 input uses SRGB color
44       encoding.   So if you use jpeg2ktopam to convert a JP2 image to PPM, it
45       changes the visual image (slightly) -- the colors in the output are not
46       the same as in the input.
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48       In  the  PAM image, the output samples are numerically identical to the
49       input samples.  If the input samples are signed, they  are  represented
50       in  two's complement form in the output (because PAM samples are always
51       unsigned).  The PAM plane numbers are identical to  the  JPC  component
52       numbers.
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54       A  JPEG-2000  image has a "precision," which is the number of bits used
55       for each code (in Netpbm lingo, "sample").   Actually,  each  component
56       has  a  separate precision.  The maxval of a PGM, PPM, or PAM output is
57       the largest number you can represent in the JPEG-2000 precision of  the
58       JPEG-2000  component  with  the greatest precision.  The samples in all
59       components are scaled to that maxval.  So if the red  component  has  a
60       precision  of 4 bits and the green component has a precision of 6 bits,
61       the maxval is 63 and the red component codes from the  JPEG-2000  image
62       are multiplied by 63/15 to generate the output samples.
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64       jpeg2ktopam  interprets  the  JPEG-2000 input with the Jasper JPEG-2000
65       library ⟨http://www.ece.uvic.ca/~mdadams/jasper/⟩ .  See  documentation
66       of  the library for details on what jpeg2ktopam handles.  Note that the
67       Jasper  library  contains  facilities  for  writing  PNM  images,   but
68       jpeg2ktopam  does  not  use those.  It uses the Netpbm library instead.
69       Note that the makers of the  Jasper  library  write  it  "JasPer,"  but
70       Netpbm  documentation  follows  standard  American  English  typography
71       rules, which don't allow that kind of capitalization.
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73       Use pamtojpeg2k to convert in the other direction.
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75       The program jasper, which is packaged with  the  Jasper  JPEG-2000  li‐
76       brary,  also  converts between JPEG-2000 and PNM formats.  Because it's
77       packaged with the library, it may exploit  it  better,  especially  re‐
78       cently  added  features.  However, since it does not use the Netpbm li‐
79       brary to read and write the Netpbm formats, it doesn't do as good a job
80       on that side.
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OPTIONS

84       In  addition  to  the options common to all programs based on libnetpbm
85       (most notably -quiet, see
86        Common Options ⟨index.html#commonoptions⟩  ),  jpeg2ktopam  recognizes
87       the following command line options:
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92       -verbose
93              This  option  causes jpeg2ktopam to issue informational messages
94              about the conversion process.
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97       -debuglevel=number
98              This option controls debug messages  from  the  Jasper  library.
99              jpeg2ktopam  passes  number  as  the  debug  level to the Jasper
100              JPEG-2000 decoder.
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EXAMPLES

106         jpeg2ktopam myimg.jpc >myimg.ppm
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ABOUT JPEG-2000

111       See the pamtojpeg2k manual(1) for general information on JPEG-2000 com‐
112       pression and the JPEG-2000 formats.
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SEE ALSO

116       pamtojpeg2k(1), jpegtopnm(1), ppm(1), pgm(1), pbm(1), pam(1),
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HISTORY

120       jpeg2ktopam was added to Netpbm in Release 10.12 (November 2002).
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122       Before  Netpbm  10.49  (December 2009), jpeg2ktopam could not convert a
123       JP2 file -- only JPC.
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DOCUMENT SOURCE

126       This manual page was generated by the Netpbm tool 'makeman'  from  HTML
127       source.  The master documentation is at
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129              http://netpbm.sourceforge.net/doc/jpeg2ktopam.html
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131netpbm documentation            08 October 2009     Jpeg2ktopam User Manual(0)
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