Incomplete/Clipped Images

or how to determine the right size for ghostscript.

If you have documents that are larger than your ghostscript default (usually A4 or US letter), you have to specify the page dimensions explicitly using the -s option. Otherwise your EPS might be cut off during rasterizing by ghostscript resulting in a wrongly calculated bounding box. You can pass all pre-defined page sizes to -s that ghostscript understands. These are currently: 11x17, ledger, legal, letter, lettersmall, archA, archB, archC, archD, archE a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, isob0, isob1, isob2, isob3, isob4, isob5, isob6, b0, b1, b2, b3, b4, b5, c0, c1, c2, c3, c4, c5, c6, jisb0, jisb1, jisb2, jisb3, jisb4, jisb5, jisb6, flsa, flse, halfletter. Unfortunately, all sizes are currently only available in portrait orientation (not landscape).

By default, ps2eps uses an already given %%BoundingBox from the source file, which often corresponds to the size of the physical page format for which the document was printed. However, you should be aware that this already specified bounding box may be not correct, thus resulting in a wrongly cropped (or even no usable) .eps-file. ps2eps can only do as good as ghostscript does in rendering the original postscript file (though ps2eps even works with negative and fractional values are contained in the original bounding box by using automatic translation). Therefore, if the given bounding box is to small or incorrect anyway, you can ignore the existing bounding box with the -B option, which will cause ghostscript to use its internal default size (or use -s). However, if the BoundingBox has negative coordinates, which is not allowed by the specification, ps2eps will shift the output to positive values.

Hint: to avoid rotating the picture if you have the original drawing in landscape format, you may use the “Encapsulated Postscript” option in the printer driver which should generate an EPS file (but with a bounding box of the sheet size!). But some Windows printer drivers are drawing the image with an offset from the bottom of the portrait page, so that a part of it is drawn outside the landscape oriented page. In this case, you'll have to specify a square size of the page using the maximum length, e.g., 29.7cm x 29.7cm for an A4 page.

Clipping

or why gets some of my text deleted above the included .eps file?

Some postscript drivers draw a white rectangle from the top left corner of the page to the right lower corner of the object. This may erase some or even all text above your imported/included EPS file, which is very annoying. In order to prevent this, most programs have a clipping option for imported .eps files (within LaTeX you can use \includegraphics*{}) for this purpose. If this is unfortunately not the case, you can use the -C option of ps2eps which will (hopefully) do it for you. Unfortunately, PScript.dll 5.2 (Windows XP) introduced new very badly behaving Postscript code (initclip) which will even override the outer clipping! Thus, a new filter had to be installed in ps2eps which will fix it.

However, because most programs clip directly on the bounding box, you still may loose some pixels of your image, because the bounding box is described in the coarse resolution of postscript points, i.e. 72 dpi. In order to prevent this, you can use the -l option or -C option (for the latter, clipping by the importing program should be disabled then) to allow for a 1 point larger bounding box. -C clips around a 1 point enlarged bounding box and -l enlarges the bounding box values by 1 point (you can also combine both options).

Included Filters

Some postscript sequences, e.g., for using specific printer features (featurebegin ...), are not working well within an .eps file, so ps2eps tries to filter them out. But please note that filters for postscript code may not work properly for your printer driver (ps2eps was mainly tested with HP and Adobe printer drivers, although it may work for all printers using the PScript.dll). In this case you can try to turn of filtering by using option -n, or try to find the bad sequence in the postscript code and adapt the filter rule in the ps2eps script (variables $linefilter, $rangefilter_begin, $rangefilter_end; linefilter is an expression for filtering single lines, rangefilter_... are expressions that filter all lines between a pattern matching $rangefilter_begin and $rangefilter_end; drop me an e-mail with your modifications). However, things may change as the printer drivers (e.g., PScript.dll) or postscript language evolve.

Some applications or drivers generate postscript code with leading or trailing binary code, which often confuses older postscript interpreters. ps2eps tries to remove such code, but it may sometimes make a wrong guess about start and end of the real postscript code (drop me an e-mail with a zipped postscript source, see section BUGS).

Comment lines or even blank lines are removed (which is the default to make .eps files smaller), which may corrupt your output. Please check the next section how to fix this. ps2eps removes blank lines and also <CR> (carriage ceturn “\r”) at the end of lines. However, nicely formatted postscript code gives a hint by using “%%BeginBinary” “%%EndBinary” comments. When ps2eps detects these comments it will refrain from any filtering action within the marked binary sections.

ps2eps filters also %%Orientation: comments by default (you can use option -O to turn off filtering), because ghostscript may “automagically” rotate images when generating PDF images, which is not desired in most cases. Hint: you can turn off that feature in ghostscript unconditionally by specifying -dAutoRotatePages=/None.

Corrupted Output

Some postscript code may get corrupted when comment lines or even blank lines are removed (which is the default to make .eps files smaller), because those files may contain encoded images which also have a % as first character in a line or use a special comment as end of image delimiter. If this is the case, use the -c option to prevent filtering comments.

Color and memory

ps2eps supports colored postscript, consequently letting ghostscript consume more resources for drawing its bitmap (roughly 6MBytes for an A4 page). bbox is reading the bitmap line by line so it consumes only minimal memory. If you experience problems with memory consumption of ghostscript, you may use the -m option for using a monochrome image. But this will probably result in wrongly determined bounding boxes with colored images, because ghostscript has to do black/white dithering and may thus suppress objects drawn in light colors.

Another option in case of memory problems and too long run times is to use the much more memory efficient internal ghostscript bbox by using the -g option.

WHY?

Other programs like ps2epsi do not calculate the bounding box always correctly (because the values are put on the postscript stack which may get corrupted by bad postscript code) or rounded it off so that clipping the EPS cut off some part of the image. ps2eps uses a double precision resolution of 144 dpi and appropriate rounding to get a proper bounding box. The internal bbox device of ghostscript generates different values (sometimes even incorrect), so using the provided bbox should be more robust. However, because normal clipping has only a resolution of 1/72dpi (postscript point), the clipping process may still erase parts of your EPS image. In this case please use the -l option to add an additional point of white space around the tight bounding box.

ACKNOWLEDGMENTS

Some people contributed code or suggestions to improve ps2eps. Here are at least some names (sorry if I forgot your name): Christophe Druet, Hans Ecke, Berend Hasselman, Erik Joergensen, Koji Nakamaru, Hans Fredrik Nordhaug, Michael Sharpe. Special thanks goes to Michael Sharpe from UCSD who suggested a lot of useful features for ps2eps and who fixed bbox to become more precise and robust.

An earlier version of this manual page was originally written by Rafael Laboissiere <rafael at debian.org> for the Debian system. Thank you Rafael!

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts.