1Pamtojpeg2k User Manual(0) Pamtojpeg2k User Manual(0)
2
6 pamtojpeg2k - convert PAM/PNM image to a JPEG-2000 code stream
7
10 pamtojpeg2k [-imgareatlx=column] [-imgareatly=row] [-tilegrdtlx=column]
11 [-tilegrdtly=row] [-tilewidth=columns] [-tileheight=rows]
12 [-prcwidth=columns] [-prcheight=rows] [-cblkwidth=columns]
13 [-cblkheight=rows] [-mode={integer|int|real}] [-compression=ratio]
14 [-ilyrrates=ratestring] [-numrlvls=number] [-progres‐
15 sion={lrcp|rlcp|rpcl|pcrl|cprl}] [-numgbits=number] [-nomct] [-sop]
16 [-eph] [-lazy] [-termall] [-segsym] [-vcausal] [-pterm] [-resetprob]
17 [-verbose] [-debuglevel=number] filename
18 Minimum unique abbreviation of option is acceptable. You may use dou‐
20 ble hyphens instead of single hyphen to denote options. You may use
21 white space in place of the equals sign to separate an option name from
22 its value.
23
27 This program is part of Netpbm(1).
28 pamtojpeg2k converts the named PBM, PGM, PPM, or PAM file, or Standard
30 Input if no file is named, to a JPEG-2000 code stream (JPC) file on
31 Standard Output.
32 The JPEG-2000 specification specifies two different formats: JP2 and
34 JPEG-2000 code stream (JPC). JP2 represents a visual image quite
35 specifically, whereas JPC is a more or less arbitrary array of codes.
36 pamtojpeg2k can't produce a JP2, but the JPC image that pamtojpeg2k
37 produces is very similar to a JP2 if the input is a PBM, PGM, or PPM
38 image or equivalent PAM image. One difference is that that RGB inten‐
39 sity values in a JP2 are SRGB values, while pamtojpeg2k produces ITU-R
40 Recommedation BT.709 values. Those are very similar, but not identi‐
41 cal. Another difference is that a JP2 can contain extra information
42 about an image that JPC cannot.
43 When the input is a PAM image other than a PBM, PGM, or PPM equivalent,
45 the JPC raster produced contains whatever the PAM raster does. It can
46 have any number of planes with any meanings; the planes are in the same
47 order in the JPC output as in the PAM input.
48 A JPC image has a "precision," which is the number of bits used for
50 each code (in Netpbm lingo, "sample"). Actually, it has a separate
51 precision for each component. pamtojpeg2k uses for the precision of
52 every component the least number of bits that can represent the maxval
53 of the input image. A JPC image does not have an independent concept
54 of maxval; the maxval of a JPC sample is the maximum value that the
55 number of bits specified by the precision can represent in pure binary
56 code. E.g. if the precision is 4, the maxval is 15. pamtojpeg2k does
57 of course scale the sample values from the input maxval to the output
58 maxval. Example: The input maxval is 99. This means JPC precision is
59 7 bits and the JPC maxval is 127. A sample value of 33 in the input
60 becomes a sample value of 43 in the output.
61 pamtojpeg2k generates the JPC output with the Jasper JPEG-2000 library
63 ⟨http://www.ece.uvic.ca/~mdadams/jasper/⟩ . See documentation of the
64 library for details on what pamtojpeg2k produces. Note that the Jasper
65 library contains facilities for reading PNM images, but pamtojpeg2k
66 does not use those. It uses the Netpbm library instead. Note that the
67 makers of the Jasper library write it "JasPer," but Netpbm documenta‐
68 tion follows standard American English typography rules, which don't
69 allow that kind of capitalization.
70 Use jpeg2ktopam to convert in the other direction.
72 The program jasper, which is packaged with the Jasper JPEG-2000
74 library, also converts between JPEG-2000 and PNM formats. Because it's
75 packaged with the library, it may exploit it better, especially
76 recently added features. However, since it does not use the Netpbm
77 library to read and write the Netpbm formats, it doesn't do as good a
78 job on that side.
79
82 Most of the options are identical in name and function to options that
83 the Jasper library JPC encoder subroutine takes. See Jasper
84 documentation ⟨http://www.ece.uvic.ca/~mdadams/jasper/⟩ for details.
85 Here, we document only options that are not direct analogs of Jasper
86 options.
87 -compression=ratio
92 ratio is a floating point number that specifies the compression
93 ratio. pamtojpeg2k will adjust quality as necessary to ensure
94 that you get this compression ratio. E.g. 4 means the output
95 will be about one fourth the size in bytes of the input file.
96 The compression ratio must be at least 1. The default is 1,
98 which means the output has all the quality of the input -- the
99 conversion is lossless.
100 Note that though Jasper library takes a compression factor, this
102 option specifies a compression ratio. The compression factor is
103 the multiplicative inverse of (1 divided by) the compression
104 ratio.
105 -verbose
108 This option causes pamtojpeg2k to issue informational messages
109 about the conversion process.
110 -debuglevel=number
113 This option controls debug messages from the Jasper library.
114 pamtojpeg2k passes number as the debug level to the Jasper JPC
115 encoder.
116
121 This example compresses losslessly.
122 pamtojpeg2k myimg.ppm >myimg.jpc
124 jpeg2ktopam will recreate myimg.ppm exactly.
126 This example compresses the file to one tenth its original size, throw‐
128 ing away information as necessary.
129 pamtojpeg2k -compression=10 myimg.pgm >myimg.jpc
131
135 JPEG-2000 is a format that compresses a visual image (or a similar set
136 of data) into a minimal number of bytes for storage or transmission.
137 In that, its goal is similar to JPEG. It has two main differences from
138 JPEG.
139 One difference is that it does a much better job on most images of
141 throwing out information in order to achieve a smaller output. That
142 means when you reconstruct the image from the resulting compressed
143 file, it looks a lot closer to the image you started with with
144 JPEG-2000 than with JPEG, for the same compressed file size. Or,
145 looked at another way, with JPEG-2000 you get a much smaller file than
146 with JPEG for the same image quality.
147 The second difference is that with JPEG-2000, you decide how much com‐
149 pression you want and the compressor adjusts the quality to meet your
150 requirement, whereas with JPEG, you decide how much quality you want
151 and the compressor adjusts the size of the output to meet your require‐
152 ment. I.e. with JPEG-2000, the quality of the result depends on the
153 compressibility of the input, but with JPEG, the size of the result
154 depends on the compressibility of the input.
155 With JPEG-2000, you can specify lossless compression, thus making it
157 compete with GIF and PNG. With standard JPEG, you always lose some‐
158 thing. (There are rumored to be variations of JPEG around that are
159 lossless, though).
160 JPEG is much older than JPEG-2000 and far more popular. JPEG is one of
162 the half dozen most popular graphics formats and virtually all graphics
163 facilities understand it. JPEG-2000 is virtually unknown.
164 There is no compatibility between JPEG and JPEG-2000. Programs that
166 read JPEG do not automatically read JPEG-2000 and vice versa.
167
171 jpeg2ktopam(1), pnmtopeg(1), ppm(1), pgm(1), pbm(1), pam(1),
172
175 pamtojpeg2k was added to Netpbm in Release 10.12 (November 2002).
176netpbm documentation 27 October 2002 Pamtojpeg2k User Manual(0)