1Pnmtojbig User Manual(0) Pnmtojbig User Manual(0)
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6 pnmtojbig - PNM to JBIG file converter
7
10 pnmtojbig
11 [options] [input-file [output-file]]
13
16 This program is part of Netpbm(1).
17 pnmtojbig reads a PBM or PGM image, compresses it, and outputs the
19 image as a JBIG bi-level image entity (BIE) file.
20 JBIG is a highly effective lossless compression algorithm for bi-level
22 images (one bit per pixel), which is particularly suitable for scanned
23 document pages.
24 A JBIG encoded image can be stored in several resolutions (progressive
26 mode). These resolution layers can be stored all in one single BIE or
27 they can be stored in several separate BIE files. All resolution lay‐
28 ers except the lowest one are stored merely as differences to the next
29 lower resolution layer, because this requires less space than encoding
30 the full image completely every time. Each resolution layer has twice
31 the number of horizontal and vertical pixels than the next lower layer.
32 JBIG files can also store several bits per pixel as separate bitmap
33 planes, and pnmtojbig can read a PGM file and transform it into a
34 multi-bitplane BIE.
35
38 In addition to the options common to all programs based on libnetpbm
39 (most notably -quiet, see
40 Common Options ⟨index.html#commonoptions⟩ ), pnmtojbig recognizes the
41 following command line options:
42 -q Encode the image in one single resolution layer (sequential
47 mode). This is usually the most efficient compression method. By
48 default, the number of resolution layers is chosen automatically
49 such that the lowest layer image is not larger than 640 × 480
50 pixels.
51 -x number
54 Specify the maximal horizontal size of the lowest resolution
55 layer. The default is 640 pixels.
56 -y number
59 Specify the maximal vertical size of the lowest resolution
60 layer. The default is 480 pixels.
61 -l number
64 Select the lowest resolution layer that will be written to the
65 BIE. It is possible to store the various resolution layers of a
66 JBIG image in progressive mode into different BIEs. Options -l
67 and -h allow you to select the resolution-layer interval that
68 will appear in the created BIE. The lowest resolution layer has
69 number 0 and this is also the default value. By default, pnmto‐
70 jbig writes all layers.
71 -h number
74 Select the highest resolution layer that will be written to the
75 BIE. By default, pnmtojbig writes all layers. See also option
76 -l.
77 -b Use binary values instead of Gray code words in order to encode
80 pixel values in multiple bitplanes. This option has only an
81 effect if the input is a PGM file and if more than one bitplane
82 is produced. Note that the decoder has to make the same selec‐
83 tion but cannot determine from the BIE, whether Gray or binary
84 code words were used by the encoder.
85 -d number
88 Specify the total number of differential resolution layers into
89 which the input image will be split in addition to the lowest
90 layer. Each additional layer reduces the size of layer 0 by 50
91 %. This option overrides options -x and -y, which are usually a
92 more comfortable way of selecting the number of resolution lay‐
93 ers.
94 -s number
97 The JBIG algorithm splits each image into a number of horizontal
98 stripes. This option specifies that each stripe shall have num‐
99 ber lines in layer 0. The default value is selected so that
100 approximately 35 stripes will be used for the whole image.
101 -m number
104 Select the maximum horizontal offset of the adaptive template
105 pixel. The JBIG encoder uses a number of neighbour pixels in
106 order to get statistical a priori knowledge of the probability,
107 whether the next pixel will be black or white. One single pixel
108 out of this template of context neighbor pixels can be moved
109 around. Especially for dithered images it can be a significant
110 advantage to have one neighbor pixel which has a distance large
111 enough to cover the period of a dither function. By default,
112 the adaptive template pixel can be moved up to 8 pixels away.
113 This encoder go up to 23 pixels, however as decoders are only
114 required to handle at least a distance of 16 pixels by the stan‐
115 dard, no higher value than 16 for number is recommended in order
116 to maintain interoperability with other JBIG implementations.
117 The maximal vertical offset of the adaptive template pixel is
118 always zero.
119 -t number
122 Encode only the specified number of most significant bit planes.
123 This option allows to reduce the depth of an input PGM file if
124 not all bits per pixel are needed in the output.
125 -o number
128 JBIG separates an image into several horizontal stripes, resolu‐
129 tion layers and planes, were each plane contains one bit per
130 pixel. One single stripe in one plane and layer is encoded as a
131 data unit called stripe data entity (SDE) inside the BIE. There
132 are 12 different possible orders in which the SDEs can be stored
133 inside the BIE and number selects which one shall be used. The
134 order of the SDEs is only relevant for applications that want to
135 decode a JBIG file which has not yet completely arrived from
136 e.g. a slow network connection. For instance some applications
137 prefer that the outermost of the three loops (stripes, layers,
138 planes) is over all layers so that all data of the lowest reso‐
139 lution layer is transmitted first.
140 The following values for number select these loop arrangements
142 for writing the SDEs (outermost loop first):
143 0 planes, layers, stripes
147 2 layers, planes, stripes
150 3 layers, stripes, planes
153 4 stripes, planes, layers
156 5 planes, stripes, layers
159 6 stripes, layers, planes
162 All loops count starting with zero, however by adding 8 to the
166 above order code, the layer loop can be reversed so that it
167 counts down to zero and then higher resolution layers will be
168 stored before lower layers. Default order is 3 which writes at
169 first all planes of the first stripe and then completes layer 0
170 before continuing with the next layer and so on.
171 -p number
174 This option allows you to activate or deactivate various
175 optional algorithms defined in the JBIG standard. Just add the
176 numbers of the following options which you want to activate in
177 order to get the number value:
178 4 deterministic prediction (DPON)
182 8 typical prediction (TPBON)
185 16 diff. layer typical prediction (TPDON)
188 64 layer 0 two-line template (LRLTWO)
191 Except for special applications (like communication with JBIG
195 subset implementations) and for debugging purposes you will nor‐
196 mally not want to change anything here. The default is 28,
197 which provides the best compression result.
198 -c The adaptive template pixel movement is determined as suggested
201 in annex C of the standard. By default the template change
202 takes place directly in the next line which is most effective.
203 However a few conformance test examples in the standard require
204 the adaptive template change to be delayed until the first line
205 of the next stripe. This option selects this special behavior,
206 which is normally not required except in order to pass some con‐
207 formance test suite.
208 -v After pnmtojbig creates the BIE, it lists a few technical
211 details of the created file (verbose mode).
212
217 Most of the format pnmtojbig creates is defined by the JBIG standard.
218 The standard, however, does not specify which values in the BIE mean
220 white and which mean black. It contains a recommendation that for a
221 single plane image zero mean background and one mean foreground, but
222 the Netpbm formats have no concept of foreground and background. And
223 the standard says nothing about values for multiple plane BIEs.
224 pnmtojbig follows Markus Kuhn's implementation of the standard in the
226 pbmtojbg program that comes with his JBIG library: If the BIE is a
227 single plane BIE, zero means white and one means black. If it is a
228 multiple plane BIE, zero means black and the maximal value is white.
229
232 This program implements the JBIG image coding algorithm as specified in
233 ISO/IEC 11544:1993 and ITU-T T.82(1993).
234
237 pnmtojbig is based on the JBIG library by Markus Kuhn, part of his
238 JBIG-KIT package. The pbmtojbg program is part of the JBIG-KIT pack‐
239 age. The most recent version of that library and tools set is freely
240 available on the Internet from anonymous ftp server ftp.informatik.uni-
241 erlangen.de ⟨ftp://ftp.informatik.uni-erlangen.de⟩ in directory
242 pub/doc/ISO/JBIG/.
243 pnmtojbig is part of the Netpbm package of graphics tools.
245
248 pnm(1), jbigtopnm(1)
249
252 There was at one time concern about the need for patent licenses to use
253 pnmtojbig, but any relevant patents expired by 2012.
254
256 This manual page was generated by the Netpbm tool 'makeman' from HTML
257 source. The master documentation is at
258 http://netpbm.sourceforge.net/doc/pnmtojbig.html
260netpbm documentation 28 July 2020 Pnmtojbig User Manual(0)