[comp.lang.postscript] PS->EPS filter

krishna@bucasd.bu.edu (Krishna Govindarajan) (02/19/91)

Does anyone know of a filter that will convert Postscript to
Encapsulated Postscript ?

raymond@math.berkeley.edu (Raymond Chen) (02/19/91)

In article <KRISHNA.91Feb18182501@bucasd.bu.edu>, krishna@bucasd (Krishna Govindarajan) writes:
>Does anyone know of a filter that will convert Postscript to
>Encapsulated Postscript ?

Cannot be done in general.  Consider:

I write a Postscript program that performs several CPU hours of numerical
analysis, and outputs either

[1] nothing, if it failed to find a solution.
[2] one page of output containing the solution it found.

The only way to figure out what value to put in the %%Pages field in
the EPS header is by actually executing the program and seeing what
happens.

(A more mundane example is a PS program that violates one of the contraints
of EPS.  For example, if it redefines macros in midstream, or downloads
a font in the middle of the document, thereby ruining any possibility
of performing page-reversal.  Some dvi-to-Postscript converters are guilty
of the latter.)

Remember, Encapsulated Postscript is a restricted form of Postscript.

My favorite analogy is viewing Postscript as the English language, and
Encapsulated Postscript as a restricted form of the English language
where you are only allowed to use words that appear on a list of 10,000
`permitted' words.

dhosek@freke.claremont.edu (Don Hosek) (02/19/91)

In article <1991Feb19.011453.5797@agate.berkeley.edu>, raymond@math.berkeley.edu (Raymond Chen) writes:
> In article <KRISHNA.91Feb18182501@bucasd.bu.edu>, krishna@bucasd (Krishna Govindarajan) writes:
>>Does anyone know of a filter that will convert Postscript to
>>Encapsulated Postscript ?
 
> Cannot be done in general.  Consider:

..

> (A more mundane example is a PS program that violates one of the contraints
> of EPS.  For example, if it redefines macros in midstream, or downloads
> a font in the middle of the document, thereby ruining any possibility
> of performing page-reversal.  Some dvi-to-Postscript converters are guilty
> of the latter.)

But then again, how often do you want to include dvi to
PostScript output in another PostScript file? (the better
solution, I would say, is to use a dvi to dvi inclusion system).

Proper PostScript also tends to be very large and very slow in
the case of DVI translations. Especially for printers with little
memory and documents with many fonts. By downloading fonts
mid-stream, one can reduce memory requirements for printing a
complicated document. Having the option to create EPS is a nice
option, but I don't really see it as a viable standard for
translated DVI files.

-dh

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