[Scribus] cmyk workflow

[jon]

Am 05.02.2007 um 16:26 schrieb Axel Bojer:

> David Eyre skrev:
>> Just looking for some views from other users. At the
>> moment, my workflow for placing images is as follows:
>>
>> 1. Create image box
>> 2. Import unedited image
>> 3. Edit image to open in the GIMP
>> 4. Re-size and crop image
>> 5. Do CMYK-separation of edited image using GIMP
>> Separation plug-in
>> 6. Save separated edited image as tif
>> 7. Back into Scribus to delete unedited image from box
>> contents
>> 8. Import edited image tif
>>
>> Am I wasting time here? Do I really need to do the
>> CMYK separation? Would the images be automatically
>> CMYK-ed when I export the page to PDF?
>
> As far as I have understood other advices on this list, you will not
> have to import images as CMYK, but just RGB and then, yes, Scribus
> should convert it to CMYK if you chose save as pdf *and* intended for  
> Print.
>
> Thus my workflow has been:
>
> 1. Import unedited image
> 2. Scale the image + its frame until it fits as I wish
> 3. Use Gimp to rescale my image to the size I found in 2)
> 4. Import the changed image
> (3 and 4 are meant to save space, I don't think you *have* to do this)
>   And when I am totally finished
> 5) Export the whole document as pdf -- then the image should be
> converted to CMYK by Scribus, or so I thought it was at least ...
>
> But I have a problem concerning this:
> Right now I got a telephone from my printer saying my pdf resulting  
> from
> these steps are not usable, but greyish instead of grasgreen.
>
> See the results yourselves here:
> http://www.bojer.no/Ariadne2006/ariadnes_aarbok2006-omslag- 
> ForSkjerm.pdf
> http://www.bojer.no/Ariadne2006/ariadnes_aarbok2006-omslag- 
> TilTrykking.pdf
>
> ("skjerm" means screen, and is the rgb variant, "Trykk" means print and
> is the one intended to be printed).
>
> When I look at it in XPD or Kpdf it really looks greyish, as he said  
> (he
> used Windows I suppose, at least he said he was using Acrobat), but on
> acrobat on Linux it show as it should, no greyish tone to it as in  
> xpdf.
>   Having repeadedly read in thes thread, that acrobat is to be trusted
> over all the other pdf-programs, I trusted it to be OK, but it seems
> not. Or is he mistaken??
>
> Now, what I have as a pdf-file is made out of many imageframes linking
> to the same picture. This gives a nice effect, and keeps the file  
> pretty
> small. But the printer was in doubt wether his equipment would be able
> to use it, I am not sure, but said I think it ought to be ok (after all
> this function is quite the same as in other DTP programs, so I excpect
> this to be no different). But he wanted me to ?flatten the image?, that
> is merge all my layers into one.

Flatten  here should mean reduce transparencies to real.
As your file looks - you are using transparancies wich are not  
printable as long as
your printer doesn't use sufficient equipment or ripping procedures.
Unauthorized rendering of transparencies sometimes leads to unwanted  
results.

> So the only reasonable way I found
> (without having to redo everything) was to export as png, put this png
> file as the only element in a new file with the same dimensions and  
> then
> export to pdf again.
> I looked at the png-file in Gimp, and it looks ok and is RGB.
> The resulting file though is really greyish. Now I am not quite sure  
> how
> to solve this, I had trusted Scribus to just solve this for me by  
> export
> time ...

You might trust scribus only if you know what you are doing. RGB to  
CMYK conversion is not a simple thing.
The color space of RGB is much wider than CMYK. Colors displayable in  
RGB are not always convertable to CMYK.
e.g. rgb (0,100,0) is by no way reproducable in cmyk it might be  
clipped to, say, cmyk (50-0-100-0).
Everything here depends on colormanagment modules, rendering intents  
and profile settings.

Settings for CMM are made in "Preferences/Colormanagement"
Activate "Colormanagement"

More generic but possibly more sufficient settings:

set profile RGB-Pictures to RGB (ECI-RGB or sRGB or Generic)
set profile CMYK-Pictures to CMYK (ISO-coated or ISO-uncoated or  
Generic)
set monitor to (ECI-RGB or sRGB or Generic)
set printer to (ISO-coated or ISO-uncoated or Generic)

set rendering intents
monitor to relative colormetric
printer to photographic or perceptive

check compensate black

You may obtain the mentionend profiles at www.eci.org, for better  
results you should install them.

Using CMM does not mean you wont run into any problems with colors wich  
cannot be converted.
But it helps a lot.

And, no, I am afraid I cannot help you with installing CMM under Linux  
or Windows.

Another way around is to change the colors in your png (in Gimp) to  
something which in your opinion
might be printable. And reimport these files.

Jon

>
> Am I doing something wrong here?
>
> I ought to have it sent and proofed today, so every help is  
> appreciated :-)
>
> Best regards
> Axel Bojer
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