Re: Printers using free software only

[Roger Leigh <rleigh@codelibre.net>]

On Tue, Jul 31, 2012 at 02:06:07PM +0000, Camaleón wrote:
> On Tue, 31 Jul 2012 19:43:13 +1200, Chris Bannister wrote:
> 
> > On Mon, Jul 30, 2012 at 04:51:11PM +0000, Camaleón wrote:
> >> I just wanted to point a scenario where the jump to a PDF filter as the
> >> default backend can have its troubles and not be nor as good nor as
> >> simple nor as easy as the white papers say. Companies have always
> >> showed different needs than users and these "jumps" are seen
> >> differently when you have to hold them as user or as admin.
> > 
> > The understanding I got from reading Roger's post was that if you are
> > using CUPS, *THEN* you are automatically using "a PDF filter paradigm"
> > because it **is considered superior/"more robust"**.
> 
> That's what CUPS developers seem to claim (?) but having used PS printers 
> and PS backend as default for all these years, I'm a bit reluctant about 
> grandiloquent wordings with no more technical proofs on the superiority 
> of one on the proposed systems over the other.

If you want technical proof, please download the specs for both from
Adobe's website and compare them.  Both are freely downloadable.
  http://partners.adobe.com/public/developer/en/ps/PLRM.pdf
  http://www.adobe.com/devnet/acrobat/pdfs/pdf_reference_1-7.pdf
The wikipedia pages for both are also reasonably informative.

The fact is, PDF *is* the continuation of PostScript.  It's just an
evolved form of PostScript in a binary format.  More accurately, both
formats are implementations of the "Adobe imaging model"; until PDF
1.4, both of these formats implemented the same set of primitives.
PDF 1.4 and later implement new additions to the imaging model, while
PostScript will not see any new releases.  If you look at all the
drawing primitives contained within PostScript, they are all right
there in PDF.  If you take any PostScript document, you can execute
it and transform all the drawing commands to their PDF equivalent.
That's why it's trivial to to the conversion.  The converse is not
always true: because PDF is a *superset* of the PostScript drawing
model, and so you potentially lose information going the other way,
because you might have to convert a single PDF primitive into multiple
PostScript primitives which only /approximate/ the PDF.

You can read a nice overview of the history and relationship between
the two here:
  http://www.prepressure.com/postscript/basics/history

I hope from the above you'll understand that is indisputable that
1) PDF has a more technically sophisticated imaging model
2) PDF is the de-facto standard for professional document printing
3) PostScript is no longer being developed, and PDF is its successor
Moving to a PDF based printing workflow is an improvement due to
being technically superior and the logical way to go.


Regards,
Roger

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