[softwarelist] Re: colour corrections

In message <e54be88d4e.arnold@arnold.>
          Arnold van der Heijden <info@xxxxxxxxx> wrote:

> When I use -for example- 100% magenta in Ovation, print this
> postcript, the file never gives, depending on the jobobtion in
> Distiller, 100% magenta in pdf.

This is not surprising. The RISC OS printer driver is strictly 
RGB-only, so what ends up in the PostScript file is always an RGB 
colour. This is not OP's fault - there simply is no way to tell the 
printer driver that a CMYK colour is desired. So, in the case of the 
standard 100% Magenta CMYK colour definition, the colour setting in 
the PostScript file reads:
  255 0 255 C
which sets 100% Red, 0% Green, 100% Blue, which is the naive 
conversion of 100% Magenta from CMYK to RGB. It is highly unlikely 
that any printing pipeline will render that as plain 100% Magenta.

By the way: It would be almost trivial to enhance the PostScript 
printer driver to allow applications to set CMYK colours. This will 
probably be done as part of the PostScript 3 driver project. Adding 
support for that to OvationPro should be very easy.

As a further aside: OvationPro does have special code to bypass the 
printer driver in order to print CMYK bitmaps to PostScript correctly. 
This has a long tradition: Impression did it already, and ArtWorks 
does it (I added that for ArtWorks 2.4).

> I tried all kind of settings, different joboptions, colour
> correction turned on or off. But I can't get 100% magenta
> as 100% magenta in pdf. It does not matter Ovation Risc Os or
> for Windows.

The only way to get CMYK colour definitions for shapes and text into a 
PDF file under RISC OS is to use a program that generates PDF files 
directly instead of going through the PostScript printer driver, which 
flattens everything to RGB. If you export as PDF from ArtWorks 2 you 
get all your original CMYK colours in the PDF file.

Martin
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Martin Wuerthner          MW Software          martin@xxxxxxxxxxxxxxx
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