1Pamtojpeg2k User Manual(0) Pamtojpeg2k User Manual(0)
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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 [-size=bytes] [-ilyrrates=[realnumber[,realnumber, ...]] [-numr‐
15 lvls=number] [-progression={lrcp|rlcp|rpcl|pcrl|cprl}] [-numgbits=num‐
16 ber] [-nomct] [-sop] [-eph] [-lazy] [-termall] [-segsym] [-vcausal]
17 [-pterm] [-resetprob] [-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 separate 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 the RGB inten‐
39 sity values in a JP2 are SRGB values, while pamtojpeg2k produces ITU-R
40 Recommendation 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 li‐
74 brary, also converts between JPEG-2000 and PNM formats. Because it's
75 packaged with the library, it may exploit it better, especially re‐
76 cently added features. However, since it does not use the Netpbm li‐
77 brary to read and write the Netpbm formats, it doesn't do as good a job
78 on that side.
79 Another format with goals similar to those of JPEG-2000 but that allows
81 for faster encoding and decoding, is JPEG-LS. CharLS
82 ⟨http://charls.codeplex.com⟩ is a package of software for using JPEG-
83 LS.
84
88 In addition to the options common to all programs based on libnetpbm
89 (most notably -quiet, see
90 Common Options ⟨index.html#commonoptions⟩ ), pamtojpeg2k recognizes
91 the following command line options:
92 Jasper Library Options
95 These options are identical in name and function to options that the
96 Jasper library JPC encoder subroutine takes. See Jasper documentation
97 ⟨http://www.ece.uvic.ca/~mdadams/jasper/⟩ for details.
98 -imgareatlx=column
102 -imgareatly=row
104 -tilegrdtlx=column
106 -tilegrdtly=row
108 -tilewidth=columns
110 -tileheight=rows
112 -prcwidth=columns
114 -prcheight=rows
116 -cblkwidth=columns
118 -cblkheight=rows
120 -mode={integer|int|real}
122 -ilyrrates=[realnumber[,realnumber, ...]]
124 -numrlvls=number
126 -progression={lrcp|rlcp|rpcl|pcrl|cprl}
128 -numgbits=number
130 -nomct
132 -sop
134 -eph
136 -lazy
138 -termall
140 -segsym
142 -vcausal
144 -pterm
146 -resetprob
148 -ilyrrates ('intermediate layer rates') lets you control
151 the compression at each layer. The compressed image is arranged in
152 layers,
153 so if you transmit it somewhere serially, enough information to make
154 a low
155 quality image arrives soon, then later more information arrives to
156 improve
157 the quality of the image, and so on until the entire image arrives.
158 The
159 value of this option is a list of ascending fractions, such as
160 '.1,.3,.5'. Each fraction says the size of the layers up to and
161 including that layer should add up to that fraction of the size of
162 the input
163 image. If the size of the entire image is limited by -compression
164 or -size, none of these numbers may exceed that limit.
165 Other Options
168 -compression=ratio
169 ratio is a floating point number that specifies the compression
170 ratio. pamtojpeg2k will adjust quality as necessary to ensure
171 that you get this compression ratio. E.g. 4 means the output
172 will be about one fourth the size in bytes of the input file.
173 The ratio concerns just the raster part of the image, with the
175 denominator being what the raster would take if it were encoded
176 the most naive way possible (e.g. 3 bytes per pixel in 8-bit-
177 per-sample RGB). It does, however, include metadata that is
178 part of the compressed raster. Because of that, it may not be
179 possible to give you your requested compression ratio at any
180 quality. If it isn't, pamtojpeg2k fails with a message saying
181 so.
182 If you don't specify this option, pamtojpeg2k gives you the best
184 compression it can without losing any quality. Because of the
185 metadata issue described above, this may mean, for a small im‐
186 age, the image actually expands.
187 This option controls the 'rate' option of the Jasper library.
189 Note that though the Jasper library takes a compression factor,
190 this option specifies a compression ratio. The compression fac‐
191 tor is the multiplicative inverse of (1 divided by) the compres‐
192 sion ratio.
193 You may not specify this with -size.
195 Before Netpbm 10.61 (December 2012), the default was a compres‐
197 sion ratio of 1, and if pamtojpeg2k could not make the output
198 that small, it just made it as small as it could, with zero
199 quality. You know this is happening when you see the warning
200 message, "empty layer generated."
201 -size=bytes
204 This option specifies the maximum size in bytes you want the
205 output image to have. This size is all-in, including headers
206 and trailers and other metadata. pamtojpeg2k will omit as much
207 information as necessary to get under this limit.
208 It is possible to specify a value impossibly small, for example
210 a value that doesn't even leave room for the image header.
211 If you do this, the program fails with an explanatory message.
212 This option controls the 'rate' option of the Jasper library.
214 You may not specify this with -compression.
216 This option was new in Netpbm 11.1 (December 2022).
218 -verbose
222 This option causes pamtojpeg2k to issue informational messages
223 about the conversion process.
224 -debuglevel=number
227 This option controls debug messages from the Jasper library.
228 pamtojpeg2k passes number as the debug level to the Jasper JPC
229 encoder.
230
235 This example compresses losslessly.
236 pamtojpeg2k myimg.ppm >myimg.jpc
238 jpeg2ktopam will recreate myimg.ppm exactly.
241 This example compresses the file to one tenth its original size, throw‐
243 ing away information as necessary.
244 pamtojpeg2k -compression=10 myimg.pgm >myimg.jpc
246
251 JPEG-2000 is a format that compresses a visual image (or a similar set
252 of data) into a minimal number of bytes for storage or transmission.
253 In that, its goal is similar to JPEG. It has two main differences from
254 JPEG.
255 One difference is that it does a much better job on most images of
257 throwing out information in order to achieve a smaller output. That
258 means when you reconstruct the image from the resulting compressed
259 file, it looks a lot closer to the image you started with JPEG-2000
260 than with JPEG, for the same compressed file size. Or, looked at an‐
261 other way, with JPEG-2000 you get a much smaller file than with JPEG
262 for the same image quality.
263 The second difference is that with JPEG-2000, you decide how much com‐
265 pression you want and the compressor adjusts the quality to meet your
266 requirement, whereas with JPEG, you decide how much quality you want
267 and the compressor adjusts the size of the output to meet your require‐
268 ment. I.e. with JPEG-2000, the quality of the result depends on the
269 compressibility of the input, but with JPEG, the size of the result de‐
270 pends on the compressibility of the input.
271 With JPEG-2000, you can specify lossless compression, thus making it
273 compete with GIF and PNG. With standard JPEG, you always lose some‐
274 thing. (There are rumored to be variations of JPEG around that are
275 lossless, though).
276 JPEG is much older than JPEG-2000 and far more popular. JPEG is one of
278 the half dozen most popular graphics formats and virtually all graphics
279 facilities understand it. JPEG-2000 is virtually unknown.
280 There is no compatibility between JPEG and JPEG-2000. Programs that
282 read JPEG do not automatically read JPEG-2000 and vice versa.
283
287 jpeg2ktopam(1), pnmtojpeg(1), ppm(1), pgm(1), pbm(1), pam(1),
288
291 pamtojpeg2k was added to Netpbm in Release 10.12 (November 2002).
292
294 This manual page was generated by the Netpbm tool 'makeman' from HTML
295 source. The master documentation is at
296 http://netpbm.sourceforge.net/doc/pamtojpeg2k.html
298netpbm documentation 1 November 2022 Pamtojpeg2k User Manual(0)