[Scribus] cmyk workflow

[Axel Bojer]

jon skrev:
> Am 05.02.2007 um 16:26 schrieb Axel Bojer:
(...)
>> 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.

Yes, i sorted that thing out :-)
The strange thing though is, is that also when all the file is just one 
single rgb tiff file I get the same issue (grayish in kpdf and xpdf, but 
not in acroread). Could someone on wondows (or mac perhaps) please take 
a look at
http://www.bojer.no/Ariadne2006/ariadnes_aarbok2006-omslag-TilTrykking-BareEttBilde.pdf
and see if it show up grayish? And then what about
http://www.bojer.no/Ariadne2006/ariadnes_aarbok2006-omslag-TilTrykking.pdf
The latter is the one with all the layers and the transparency.
By me they show up just the same. So how am I supposed to know if the 
printer can use them or not? (OK, I know, I should be carefull with 
transparency, but apart from that, I mean ...)

For reference, here is the image file:
http://www.bojer.no/Ariadne2006/ariadnes_aarbok2006-omslag-somBildeGB.tiff

>> 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.
(...)
I  will take a look at your suggestions, especially if someone can tell 
me if the last file is not ok :-/

> 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.

Yes, but grasgreen is almost the only colour (along with some tones of 
yellow), is that a colour especially tricky to convert from rgb to cmyk?

Best regards
Axel Bojer