1Pstopnm User Manual(0) Pstopnm User Manual(0)
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6 pstopnm - convert a PostScript file to a PNM image
7
10 pstopnm
11 [-stdout]
13 [-forceplain]
15 [-help]
17 [-dpi=dpi]
19 [-xsize=pixels] [-ysize=pixels]
21 [-xborder=frac] [-yborder=frac] [-landscape]
23 [-portrait]
25 [-nocrop]
27 [-pbm
29 |-pgm
31 |-ppm]
33 [-llx=s] [-lly=s] [-urx=s] [-ury=s]
35 [-verbose]
37 [-xmax=pixels] [-ymax=pixels]
39 [-textalphabits={1,2,4}]
41 psfile[.ps]
44
47 Minimum unique abbreviation of option is acceptable. You may use dou‐
48 ble hyphens instead of single hyphen to denote options. You may use
49 white space in place of the equals sign to separate an option name from
50 its value.
51
54 This program is part of Netpbm(1).
55 pstopnm reads a PostScript file as input and produces PBM, PGM, or PPM
57 images as output. This program simply uses GhostScript to render a
58 PostScript file with its PNM device drivers. If you don't have Ghost‐
59 Script installed or the version you have installed was not built with
60 the relevant PNM device drivers, pstopnm will fail. You can see if you
61 have the proper environment by issuing the command gs --help . If it
62 responds and lists under "Available Devices" pbm, pbmraw, pgm, pgmraw,
63 pnm, pnmraw, ppm, or ppmraw, you're in business.
64 It's important to understand that pstopnm is a Netpbm image file format
66 converter only in the broadest sense of the word, because Postscript is
67 far from an image file format. What pstopnm really is is a Postscript
68 renderer - an image generator. One place you'll notice the difference
69 is where you expect pstopnm | pnmtops to be idempotent (which is not
70 the case). There are details on this kind of conversion below.
71 pstopnm uses the value of the GHOSTSCRIPT environment variable as the
73 file name for the Ghostscript program. If GHOSTSCRIPT is not set,
74 pstopnm searches your PATH for a regular file named gs. If it doesn't
75 find one, it assumes Ghostscript is in the file /usr/bin/gs.
76 pstopnm does not use the Netpbm libraries to generate the output files,
78 so may not be entirely consistent with most Netpbm programs.
79 psfile[.ps] is the name of the input file. pstopnm will add the ps to
81 the end of the name you specify if no file exists by the exact name you
82 specify, but one with .psadded does. For Standard Input, use - or just
83 don't give any argument.
84 If you use the -stdout option or your input is from Standard Input,
86 pstopnm outputs images of all the pages as a multi-image file to Stan‐
87 dard Output. Otherwise, pstopnm creates one file for each page in the
88 Postscript input. The files are named as follows: If the input file is
89 named psfile.ps, the name of the files will be psfile001.ppm,
90 psfile002.ppm, etc. The filetype suffix is .ppm, .pgm, or .pbm,
91 depending on which kind of output you choose with your invocation
92 options. If the input file name does not end in .ps, the whole file
93 name is used in the output file name. For example, if the input file
94 is named psfile.old, the output file name is psfile.old001.ppm, etc.
95 Note that the output file selection is inconsistent with most Netpbm
97 programs, because it does not default to Standard Output. This is for
98 historical reasons, based on the fact that the Netpbm formats did not
99 always provide for a sequence of images in a single file.
100 When your input is from Standard Input, you may feed multiple Encapsu‐
102 lated Postscript documents, one after another, and pstopnm converts
103 every document and places it in the Standard Output stream as an image.
104 But if your input is from a named file, pstopnm expects the file to be
105 an Encapsulated Postscript file, which means it contains only one Enap‐
106 sulated Postscript document. If the file contains multiple concate‐
107 nated documents, pstopnm ignores every document but the first. This
108 distinction does not exist for non-EPSF Postscript input - pstopnm gen‐
109 erates an output image for each page of the input regardless of whether
110 the input is from Standard Input or from a named file.
111 Note that you can generate both kinds of files - concatenated EPSF and
113 multi-page non-EPSF - with pnmtops, selecting with the -setpage option.
114 Each output image contains a rectangular area of the page to which it
116 pertains. See the Dimensions section ⟨#dimensions⟩ for details on
117 what part of the input image goes into the output image and how big it
118 is in the output and what borders and margins are in the output image.
119 It has been reported that on some Postscript Version 1 input, Ghost‐
121 script, and therefore pstopnm, produces no output. To solve this prob‐
122 lem, you can convert the file to Postscript Version 3 with the program
123 ps2ps. It is reported that the program pstops does not work.
124 Dimensions
127 This section describes what part of the input image gets used in the
128 output and the dimensions of the output, including borders and back‐
129 ground.
130 Note that an output image is associated with a single input page.
132 pstopnm starts by taking a rectangular area from the input page. That
134 is called the subject image.
135 pstopnm may add borders to the subject image to form what is called the
137 bordered subject image.
138 pstopnm places the bordered subject image in the center of the output
140 image and clips the edges as necessary to fit the computed output image
141 size.
142 The location of the subject image in the Postscript input page is
144 defined by four numbers, the lower left corner and the upper right cor‐
145 ner x and y coordinates. These coordinates are usually specified by
146 the BoundingBox DSC statement (a Postscript comment) in the PostScript
147 file, but they can be overridden by the user by specifying one or more
148 of the following options: -llx, -lly, -urx, and -ury.
149 The presence and thickness of a border to be added to the subject image
151 to form the bordered subject image is controlled by the options -xbor‐
152 der and -yborder. If pstopnm does not find a BoundingBox statement in
153 the input, and you don't specify image area coordinates on the command
154 line, pstopnm uses default values. If your input is from Standard
155 Input, pstopnm does not use the BoundingBox values (because of the
156 technical difficulty of extracting that information and still feeding
157 the file to Ghostscript), so you either have to specify the image area
158 coordinates or take the default.
159 The output image size is a confusing thing. In a Postscript file,
161 things have spatial dimensions. For example, a particular line may be
162 3 centimeters long. A Postscript printer is supposed to print the line
163 3 centimeters long, using however many pixels that takes, without
164 regard to how big the sheet of paper on which it is printing is. In a
165 PNM image, by contrast, there is no spatial dimension; there are only
166 pixels. You might have a line that is 100 pixels long, but the PNM
167 image says nothing about how long that line should be on a printed
168 page.
169 pstopnm fills the role of a Postscript printer. The PNM image is a
171 virtual printed page. pstopnm must determine how many pixels it will
172 use in the output image to represent an inch of input image, which is
173 the "output device resolution." Think of it as the number of dots per
174 inch the virtual printer prints on the virtual page.
175 The simplest thing is for you to tell pstopnm exactly what output
177 device resolution to use, using the -dpi option. If you say for exam‐
178 ple -dpi=300 and the bordered subject image is 2 inches by 3 inches,
179 the PNM output will be 600 pixels by 900 pixels. Using this method,
180 the output device resolution has to be the same in both directions.
181 Or you can set the output image dimensions with -xsize and -ysize. For
183 example, if you say -xsize=1200 -ysize=1800 and the bordered subject
184 image is 2 inches wide by 3 inches high, the output image is 1200 by
185 1800 pixels, with each pixel representing 1/600 inch of input image.
186 In the unlikely event that you want different output device resolutions
188 in the two directions, you could use -xsize and -ysize to do that. In
189 the above example, if you change -ysize to 900, a pixel still repre‐
190 sents 1/600 inch horizontally, but 1/300 inch vertically.
191 If you specify one of -xsize and -ysize and not the other, pstopnm
193 defaults the other such that the output device resolution is the same
194 in both directions.
195 The "x" and "y" of -xsize and -ysize refer to the image being printed
197 on the page, not the page. So if pstopnm prints it in landscape orien‐
198 tation, "x" would pertain to the vertical direction on the page, i.e.
199 the vertical direction in the output PNM image.
200 If you specify neither the output size nor the output device resolu‐
202 tion, pstopnm does some weird computation which exists mainly for his‐
203 torical reasons:
204 If you specify -nocrop, pstopnm uses the values of -xmax and -ymax for
206 the output image dimensions. These default to 612 and 792 pixels,
207 respectively.
208 The final case, the default, is where you don't specify any size or
210 resolution options or -nocrop. This is the most complicated case. In
211 this case, pstopnm first chooses an output device resolution that would
212 generate the number of pixels indicated by -xmax and -ymax from the
213 bordered subject image. Then, based on that resolution, it chooses an
214 output image size that is just large enough to accommodate the subject
215 image (no borders). Remember (above) that pstopnm trims the edges of
216 the bordered subject image to fit the computed output size.
217 Ghostscript Limitations
221 Tests done in 2013 with Ghostscript 8.71 indicate that Ghostscript's
222 pgmraw output driver has some kind of rounding error that causes the
223 pixel values to change slightly, and that means pstopnm generates
224 incorrect output when you have monochrome Postscript input. But with
225 color Postscript input, pstopnm uses Ghostscript's ppmraw output driver
226 and generates correct PPM output.
227 Usage Notes
231 There is some good advice on converting to and from Postscript, in the
232 document Postcript File Conversions" (1) by Andrew T. Young.
233 Reversible Conversion
235 If you're trying to do the equivalent of the naive pnmtops | pstopnm,
237 the following steps will do it.
238 $ pnmtops -nocenter -equalpixels -dpi 72 -noturn testimg.ppm > testimg.ps
240 $ pstopnm -xborder=0 -yborder=0 -xsize=XSIZE -ysize=YSIZE \
241 -portrait -stdout -quiet testimg.ps >testimg2.ppm
242 XSIZE and YSIZE above are the image dimensions, which you can get from
244 testimg.ps like in the following example (the grep, awk and echo com‐
245 mands are just to help demonstrate how the other commands work - you
246 wouldn't use those in a program).
247 $ grep "BoundingBox" testimg.ps
249 %%BoundingBox: 0 0 227 149
250 $ awk '/%%BoundingBox/ {print $4,$5}' testimg.ps
252 227 149
253 $ xysize=$(awk '/%%BoundingBox/ {print "-xsize="$4,"-ysize="$5}' testimg.ps)
255 $ echo $xysize
256 -xsize=227 -ysize=149
258 $ pstopnm -xborder=0 -yborder=0 $xysize -portrait ... testimg.ps
260 Note that Ghostscript bugs can keep this from doing a perfect
262 reversible conversion.
263
267 In addition to the options common to all programs based on libnetpbm
268 (most notably -quiet, see
269 Common Options ⟨index.html#commonoptions⟩ ), pstopnm recognizes the
270 following command line options:
271 -forceplain
275 forces the output file to be in plain (text) format. Other‐
276 wise, it is in raw (binary) format. See pbm(1), etc. Use this
277 instead of the -plain common option if you need plain format
278 output.
279 -llx=bx
282 selects bx as the lower left corner x coordinate (in inches) on
283 the Postscript input page of the subject image. See the
284 Dimensions section ⟨#dimensions⟩ .
285 -lly=by
288 selects by as the lower left corner y coordinate (in inches) on
289 the Postscript input page of the subject image. See the
290 Dimensions section ⟨#dimensions⟩ .
291 -landscape
294 renders the image in landscape orientation.
295 If you specify neither -portrait nor -landscape, pstopnm chooses
297 the orientation that best fits the image on the output page.
298 Landscape means printed sideways on the page, not printed the
300 long way. Those are different things if the long edge of the
301 page is the top one.
302 -portrait
305 renders the image in portrait orientation.
306 See -landscape.
308 -nocrop
311 This option causes pstopnm to make the output image exactly the
312 dimensions of the bordered subject image. By default, pstopnm
313 makes the output image the dimensions specified by -xmax and
314 -ymax. See the Dimensions section ⟨#dimensions⟩ .
315 -pbm
318 -pgm
320 -ppm selects the format of the output file. By default, all files
322 are rendered as PPM.
323 -stdout
326 causes output to go to Standard Output instead of to regular
327 files, one per page (see description of output files above).
328 Use pnmsplit to extract individual pages from Standard Output.
329 -urx=tx
332 selects tx as the upper right corner x coordinate (in inches) on
333 the Postscript input page of the subject image. See the
334 Dimensions section ⟨#dimensions⟩ .
335 -ury=ty
338 selects ty as the upper right corner y coordinate (in inches) on
339 the Postscript input page of the subject image. See the
340 Dimensions section ⟨#dimensions⟩ .
341 -verbose
345 prints processing information to stdout.
346 -xborder=frac
349 specifies that the left and right borders added to the subject
350 image are to be frac times the subject image width. The default
351 value is 0.1. See the Dimensions section ⟨#dimensions⟩ .
352 -xmax=xmax
356 specifies that the output image is to be xmax pixels wide. The
357 default is 612. See the Dimensions section ⟨#dimensions⟩ .
358 -xsize=xsize
362 specifies that the output image is to be xsize pixels wide. See
363 the Dimensions section ⟨#dimensions⟩ .
364 -yborder=frac
367 specifies that the top and bottom borders added to the subject
368 image are to be frac times the subject image height. The
369 default value is 0.1. See the Dimensions section ⟨#dimensions⟩
370 .
371 -ymax=ymax
375 specifies that the output image is to be ymax pixels high. The
376 default is 792. See the Dimensions section ⟨#dimensions⟩ .
377 -ysize=ysize
380 specifies that the output image is to be ymax pixels high. See
381 the Dimensions section ⟨#dimensions⟩ .
382 -dpi=dpi
385 specifies the output device resolution, in dots per inch, of the
386 Postscript printer that pstopnm simulates. This is the number
387 of PNM pixels pstopnm generates for each inch of image. See the
388 Dimensions section ⟨#dimensions⟩ .
389 This option was new in Netpbm 10.21 (March 2004).
391 -textalphabits={1,2,4}
394 This controls subsample antialiasing of text. Antialiasing is a
395 form of smoothing that eliminates jagged edges on characters.
396 Subsample antialiasing is a kind of antialiasing that uses sub‐
397 pixels in a box, and the value of this option is the size of
398 that box. 4 gives you the best looking output, while 1 causes
399 no antialiasing. Smaller numbers make pnmtops use less CPU
400 time.
401 Pstopnm uses Ghostscript's TextAlphaBits parameter for this.
403 The default is 4.
405 This option was new in Netpbm 10.53 (December 2010). Older ver‐
407 sions of pstopnm do no antialiasing.
408
414 The program will produce incorrect results with PostScript files that
415 initialize the current transformation matrix. In these cases, page
416 translation and rotation will not have any effect. To render these
417 files, probably the best bet is to use the following options:
418 pstopnm -xborder 0 -yborder 0 -portrait -nocrop file.ps
420 Additional options may be needed if the document is supposed to be ren‐
422 dered on a medium different from letter-size paper.
423
426 gs, pnmtops(1), psidtopgm(1), pbmtolps(1), pbmtoepsi(1), pnmsplit(1),
427 pstofits
428
433 Copyright (c) 1992 Smithsonian Astrophysical Observatory
434 PostScript is a Trademark of Adobe Systems Incorporated.
436
440 Alberto Accomazzi, WIPL, Center for Astrophysics.
441
443 This manual page was generated by the Netpbm tool 'makeman' from HTML
444 source. The master documentation is at
445 http://netpbm.sourceforge.net/doc/pstopnm.html
447netpbm documentation 06 December 2013 Pstopnm User Manual(0)