Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!oliveb!sun!sears
From: sears@sun.uucp (Daniel Sears)
Newsgroups: comp.lang.postscript
Subject: Re: How to access the VM image in a PostScript printer
Summary: it can be done.
Message-ID: <80342@sun.uucp>
Date: 7 Dec 88 00:41:55 GMT
References: <4337@pbhyf.PacBell.COM> <1657@basser.oz>
Organization: Sun Microsystems, Inc. - Mtn View, CA
Lines: 39

In article <1657@basser.oz>, jaa@basser.oz (James Ashton) writes:
> In article <4337@pbhyf.PacBell.COM> kjk@pbhyf.PacBell.COM (Ken Keirnan) writes:
> >There is a commercial product available for the Macintosh that can
> >send a PostScript file to the printer and capture the bit image from
> >the printer.  Is this capability unique to the Apple LaserWriter or
> >can this be done with any PostScript printer?  I'm not interested in
> >the Mac product but in the mechanism for capturing the bit image.
> >Anyone know?
> 
> I think you'll find that Apple made very sure that this sort of thing
> was extremely difficult to do (read impossible using postscript) and
> that Adobe and indirectly the copyright holders on the fonts used would
> have made sure of this also.  Otherwise any fool could get in and get
> bitmap copies of all the copyrighted fonts at any size.  This would be
> bad for Apple but very good for us.  In this vein, if by some miracle
> you have found a way (read extremely unlikely bug in the PostScript
> implementation) to do this:  please PLEASE tell me now so I can make
> a fortune pirating fonts.
> 
> 					James Ashton.

The issue here is not whether you can read the fonts in a PostScript
printer.  Fonts are encrypted descriptions of the forms of characters.
Being able to read the "bit image from the printer" means being able to
read the contents of the frame buffer in a printer.  There is a PostScript
operator that does just this: renderbands.  LaserTalk (from Emerald City
Software) uses this operator to read back the contents of the frame buffer
in a PostScript printer to preview an image.  It's slow, but it works.  In
response to Ken's original question, this feature is not unique to Apple's
printers.  It is part of the PostScript language design and is available
in every printer that includes a frame buffer (PostScript devices without
frame buffers include the Linotype series and (I think) the Varityper VT-600).

--Dan
-- 
Daniel Sears                Sun Microsystems, Inc.
Technical Publications      MS 5-42
(415) 336-7435              2550 Garcia Avenue
sears@sun.com               Mountain View, CA  94043