[Scribus] pantone colors

[Christoph Schäfer]

Hi Gustavo,
> >
> > Spot colours aren't "generated" in a PDF, only the inforomation for the
> > printer that colour "xyz" is a spot colour called "Pantone blah". The
> > printer then knows that he has to use an extra plate to print this
> > colour.
>
> What you mean by printer in this context ? Is it the guy behind the desk at
> the print shop? Or the machine that prints?

The guy operating the RIP ;)

>
> Anyway, the question is:
>
> do the above steps enable me to produce a PDF which contains the right
> indications for a "print shop" to produce Pantone colors for me?

Yes.

>
> (even if I had to look them up on a book, and the representation manually I
> picked for them on the screen is not very faithful)
>
> Can I hand over such PDF and expect them to understand it, with no further
> questions asked?

"With no further questions asked" is always a bad idea. Success in printing 
has a lot do with communication between human beings, since there are 
hundreds of uncertainties. It's almost the same as asking a doctor for help 
by describing shortly what you think is wrong with you.

>
> > > If so, the missing bit is an algorithm to display them "correctly" on
> > > screen, right?
> >
> > No ink colour can be displayed "correctly" on screen. It is possible to
> > come cery close, but accuracy is almost impossible.
>
> I am aware of that, that's why I used the "". I suppose "very close" is
> what programs that claim Pantone support do...

They don't even do that. Read the disclaimers!


>
> Can you explain the difference between a spot colour and a non-spot color
> in terms of what is stored on the PDF?

A spot colour is stored as a separate colour (only the name of the colour) in 
the PDF file, whereas a process colour is stored in CMYK/RGB values. The 
developers will be able to explain the technical details better than I ;)

>
> > The only way to handle spot colours effectively is to buy a colour book.
> > colour books generally contain all informations needed for output: Name,
> > RGB, CMYK values, HTML codes etc. You have to choose a colour from that
> > printed book, type in the values (for printing usually CMYK) and the
> > name. When you export to PDF or Postscript you can decide if you want to
> > override the spot colour option and let the colour be composed by process
> > colours instead.
> >
> > > So, how can I know when the PDF really contains Pantone colors?
> >
> > It doesn't. See above.
>
> It must somehow, or else marking it as "spot color" would have no effect. I
> don't mean "containing the colors", the question is more:
>
> How do I know if this foobar.pdf contains the bits which mark my spot
> colors as spot colors with the correct names assigned?
>
> Sorry for not understanding at first :-)

You need special software for this. AFAICT, none of them is available for 
Linux yet :(

>
> Best regards
> Gustavo

Cheers,

Christoph