[scribus] No real CMYK black possible??

[Tino Schwarze]

On Sun, Jun 22, 2008 at 09:36:31PM -0400, Andrew A. Gill wrote:

> > Thanks, I verified that using my testfile and cmyk colors come out as
> > expected. I can't check the images this way, though. Strange: When I run
> > the EPS file through ghostscript[1], my 40/40/40/100 black seems to get
> > converted to 0/0/0/100 black - at least I can only see this kind of
> > black in Cinepaint. :-(
> 
> Two things that I forgot to mention:
> 
> 1.) Use postscript, not encapsulated postscript.  There shouldn't 
> be any difference, but it's better to remove any possibility of 
> error. (print to file using postscript)
> 
> 2.) I'm getting a spot color (SpotRich_Black) in my PS outputs. 
> Looks to be Rich Black.  See below.

Me too. After I unchecked the "registration color" checkbox, the Rich
Black came out as 0.4 0.4 0.4 1 in the EPS as expected. It doesn't come
through to TIFF though.

> And now a third point:
> 
> 3.) I tried printing separations, and I got interesting results.

It looks like ghostscripts eats some colors. 

> The black separation shows everything pure black, except the RGB 
> black image, which is rather lighter than the rest (to be 
> expected).  The cyan separation only shows the RGB black and the 
> stroke around Total Black.  The magenta and yellow separations 
> both show the same as the cyan, though the magenta separation of 
> the RGB image is lighter than the cyan separation, and the yellow 
> is much lighter than all of them.  The stroke around the total 
> black appears to remain the same intensity.
> 
> As to the spot color, it is only present in the stroke around the 
> Rich Black box.  It is not visible in any of the separations, 
> even if I turn on convert spot colors to process colors.

I get the same results. Looks like a Ghostscript problem to me. :-(
Hm, maybe I'll check the latest ghostscrip version.

The overall summary of my experiments: There seems to be no way to
get a CMYK image from a CMYK PDF on Linux, since the only way is through
Ghostscript which doesn't preserve CMYK colors 1:1.

Thanks,

Tino.

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