[Scribus] CMYK - one last try

[David Purton]

On Tue, Dec 07, 2004 at 07:06:49AM +1100, Owen wrote:
> On Mon, 6 Dec 2004 22:53:58 +1030
> David Purton <dcpurton at chariot.net.au> wrote:
> 
> 
> > > I think if I was to give a printer a pdf, I would give him the one
> > > from Scribus
> > >
> > > If I had to produce my own separations, I woulld be happy with Scribus
> > > output.
> > > 
> > 
> > You mean the "Print Separations" from Scribus? Did you get one black
> > square on each plate? 
> > 
> > I would certainly be happy with these results, but you may not be if you
> > are expecting the output to look like what you see on your screen in
> > Scribus. If you sent those separations to a printer, I know from
> > experience you would get something like the output you see in acroread
> > of the ps2pdf created pdf.
> 
> I have bundled up a scribus document with 4 images, 
> Your original eps
> ImageMagick's tif
> Gimp's tif
> Gimp's png
> 
> 
> http://www.pcug.org.au/~rcook/cmyk.tar.gz   (15284 bytes)
> 
> If I go to the print preview (view cmyk and I am using cvs 3 Dec), I
> get perfect separations for all images though the eps now shows a part
> black border, mind you that black is perfectly separated
> 
> 

Thanks for you reply Owen,

What do you mean by perfect? :) Post a pdf of your seps as well.

You might be interested in the Separations corelDRAW comes up with:

http://marshwiggle.net/owen_seps.pdf

CMYK.tif from image magick is a tif in CMYK colour space. -
Interestingly ImageMagick has made the black square 100C100M100Y100K. I
had not realised this before separating it. I shall have to look for a
better way to go from eps to tif.

CMYK_G.tif is a tif in RGB colour space (obviously - since it's the only
kind gimp can produce).

Use tiffinfo to look at the difference between the two tifs. 

CorelDRAW has separated this assuming that it is using sRGB for the
input profile and Euroscale Coated for the output profile.

CMYK.eps and CMYK.tif, since they do not have profiles attached are
assumed to be already press ready and are just separated based on the
"numbers" that are actually in the files.

The point I'm trying to make in all these ravings is that the RGB tif
and the CMYK tif are *different*. They will look different when printed
and they should look different on screen.

The fifth page of the above pdf is the composite output. The output
profile is again Euroscale Coated - which again only comes into play in
CMYK_G.tif, since the other two images are already in the output CMYK
colour space. (Again make sure you look at this in acroread, not xpdf)

In corelDRAW - my on screen proof looks like this fifth page. If I print
the separations on the first four pages, then  will also get something
like the fifth page.

My problem with scribus is that all three images look much the same on
screen - like CMYK_G.tif does on page five of my pdf. When I print
separations from Scribus (with icc profiles applied) then the CMYK.eps
separates the same as from Corel, but both tifs separate like Corel
separates CMYK_G.tif.

I argue this is all wrong. Scribus is only coming up with correct
separations when all objects are assumed to by incoming in RGB space.


Hope this helps to clarify.

cheers

dc


-- 
David Purton
dcpurton at chariot.net.au
 
For the eyes of the LORD range throughout the earth to
strengthen those whose hearts are fully committed to him.
                                 2 Chronicles 16:9a
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