[softwarelist] Re: Quercus, PDF problems

  • From: Mike Williams <akalat@xxxxxxxxxxx>
  • To: <davidpilling@xxxxxxxxxxxxx>
  • Date: Sat, 06 Oct 2007 11:16:07 +0100

On 5/10/07 9:06 pm, "John Cartmell" <john@xxxxxxxxxxxxxxxxxxxx> wrote:

> On 05 Oct, David Pilling <flist@xxxxxxxxxxxxxxxxxxx> wrote:
>> In message <4f2d08d299john@xxxxxxxxxxxxxxxxxxxx>, John Cartmell
>> <john@xxxxxxxxxxxxxxxxxxxx> writes
>>> That's the problem. I don't know - and didn't get the feedback needed.
>>> In the past RISC OS pdfs have got the response from printers "Can't resolve
>>> that page".
> 
>> Of course there is always the possibility that the specialist software
>> handling your pdfs makes unwarranted assumptions about them - expecting
>> them to originate from a particular Mac program.
> 
>> I suppose trying your pdfs in Adobe software would be the test of if
>> they were correct.
> 
>> I wonder if GhostScript would be any better - it obviously has a much
>> wider userbase than RiScript.
> 
>> I presume experiments are costly. I wasn't making a comment on the use
>> of Macs, I was purely curious about why there was a problem.
> 
>> To put it another way, if you knew what the problem was it might help
>> others, or someone might be able to fix it.
> 
> Part of the reason for publishing that article was to get feedback - like
> this. Martin has said - elsewhere and recently - that the problem is not with
> producing pdfs but with producing correct PostScript files. I would like to
> understand how the PostScript files that I produce (in RISC OS) can be (they
> are) turned into acceptable pdfs on a Mac.
> 
> I'd like to see a list of do this - and don't do that - that will *guarantee*
> pdfs that you can, with confidence, hand to any commercial printer knowing
> that they will work OK. I'm pretty certain that won't be possible (produced on
> RISC OS or any other platform) because of the changes that those printers will
> be making with their software - but I'd like to see a way of getting as close
> to that as possible - and knowing what action to take when problems arise.

Anyone who has access to a Mac as well as RISC OS should have no problems.
Generate PostScript under RISC OS ensuring that ALL fonts are embedded.
Transfer to Mac and run through Distiller using 'Press' settings to generate
PDF. The only issues I had were with bitmapped images. Because of the
peculiar way in which Acorn handles greyscale images they can appear in the
PDF file with visible artefacts in the form of small rectangles. This is,
apparently, because PostScript works with floating point arithmetic and PDF
works with fixed point arithmetic resulting in occasional small rounding
errors in conversion from PostScript to PDF.

The other issue I had was in trying to provide CMYK format colour images.
This may not be so much of a problem now that more and more printers'
software will itself handle RGB to CMYK conversion.

In both cases the reliable workaround was to transfer each image as a TIFF
file to the Mac, load into Photoshop and resave as a Photoshop EPS file
(converting to CMYK or any other format on the way). The EPS can then be
transferred back to RISC OS and imported into the original (Ovation Pro or
Impression Plus) document with the same image position and scaling as
before. If, when saving the EPS file on the Mac, you select a TIFF preview
then this will be visible in the Ovation Pro frame just like the original
image. I never had any problems with this approach when handling work
originated under RISC OS which needed printing.

I had already started to adopt this approach when John Cartmel took over
Acorn Publisher as it then was.

Mike Williams

Other related posts:

  1. Home
  2. davidpilling
  3. Archive
  4. 10-2007