[scribus] b/w document: PDF greyscale or printer?

[Hal V. Engel]

On Thursday 03 September 2009 07:55:02 am Peter Nermander wrote:
> > now, and in the last few issues experienced problems.  Eventually
> > it turned out that it was all caused by me exporting PDFs for
> > "Printer", not "Greyscale".  PDFs exported for "Printer" are
> > actually RGB, not greyscale - even though the entire document
> > doesn't contain a single element in color.  So a description of
> > what these two options do would be welcome  :-)
>
> It has been mentioned several times on this list.
>
> Printer means PDF is exported as CMYK (the "printer" here means the
> profession, not the device)

I always thought that this means that the output will be converted to the 
"Printer:" color space that is set in the Color Management Preferences dialog.   
That color space could be a CMYK, RGB, Gray or device N color space depending 
on the profile that is set in the Color Management preferences.  And no it does 
mean the "printer" (as in a device) and not the profession since the profile 
set in the CM preferences dialog is for a specific device.

>
> Screen/web means RGB 

I think Screen/Web means that the document will be converted to sRGB.  Saying 
that a document is converted to RGB is colorimetricly meaningless.

> (and is to be used for most desktop and office
> printers, because they are made to accept RGB data and trying to print
> a CMYK PDF to those devices mean that the CMYK will first be converted
> to RGB by the computer and then to CMYK again by the printer driver)

This is true on Windows and OS/X using vendor supplied drivers IF you don't 
have a good profile for the printer/paper/ink/driver and work flow.  Many of the 
drivers used on *nix machines can also accept at a native level CMYK, Gray and 
even in some cases device N input.   For example the GutenPrint drivers 
support RGB, CMYK, Gray and device N input at a native level on many printers 
including the Epson R2400 I have.

>
> Grayscale means (if I understand right) CMYK without CMY (intended for
> when you print with only black ink).

I am not sure about this but I would expect a "Gray" color space document to 
only have one subtractive channel.

Hal