Re: Printers using free software only
On Thu, Jul 26, 2012 at 02:39:29PM +0000, Camaleón wrote:
> On Wed, 25 Jul 2012 23:23:14 +0300, Andrei POPESCU wrote:
> >>
> >> No major application on the popular DEs outputs PostScript when
> >> printing.
> >
> > I was trying to point out that a PS printer is also a PDF printer.
>
> And better than PDF, I'd say.
>
> PostScript specification is by far a more professionally-oriented
> language that PDF format (aside comment: last time I checked you could
> embed a 3D video animation on a PDF sheet and all kind of
> "dynamicallities"... geez!).
No, while PDF does perhaps allow such things, it's far far better than
PostScript.
PostScript is difficult to process due to the fact that it's a fully-
featured Turing-complete language. It's difficult to parse to find
page boundaries since you have to process the whole document to be
sure. There are standards to mark up the PostScript to make this
simpler, but they are optional and can be wrong. Processing it can
have unbounded complexity.
PDF is a subset of PostScript and does not have a Turing-complete
grammar. It means it's possible to process it very fast, and it
has structure which PostScript does not. For example, selecting a
subset of pages is very fast, and doesn't require processing all the
pages in the whole file to extract a few pages. So things like page
subsetting, rescaling, n-up printing, etc. become trivial. Also,
take a simple task like copying some text out of a PDF; it's easy,
because it has a higher-level structure than PostScript. Doing it
with PostScript is decidedly non-trivial. Not only do you have to
find the text (which might be printed letter by letter), you also have
to deal with font subsetting and encoding issues. It might even be
bitmaps.
PDF is also a superset in other areas. For example, it has support
for transparency, gradients (including meshes) and other advanced
drawing and rendering which PostScript can't support. If you print
this as PostScript, it has to approximate the transparency, gradients
etc. with thousands of smaller objects, and the file size can balloon
to tens of times its original size (I've had multi-gigabyte PostScript
files generated from tens to hundreds of megabyte PDFs). Being able to
print natively as PDF means you can just transfer the PDF and avoid
such lossy conversion. It also supports colour profiles for accurate
colour reproduction. A native PDF workflow is far, far better and
vastly more flexible than a native PostScript workflow.
PDF/A is normally used for printing--it's the sensible subset without
all the pointless bells and whistles. PDF is the successor to
PostScript, which eliminates the mistakes of the format (being fully
programmable, and lacking in many modern features), while adding a
few of its own (stupid additional features). Ignore those extra
features, and it's a much, much better solution than PostScript.
Regards,
Roger
--
.''`. Roger Leigh
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