[Scribus] cmyk workflow

[Axel Bojer]

jon skrev:
(...)
>> 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 ...)
> 
> Ok. If you use transparencies and your printer cannot handle it - you 
> will get your frontmost plants black in white box.
> The plants in the background will have some sort of grid lines and their 
> boxes will overlay but not overprint.
> Something like that, depending on the rendering engine.
> This said ...
> 
>> For reference, here is the image file:
>> http://www.bojer.no/Ariadne2006/ariadnes_aarbok2006-omslag-somBildeGB.tiff 
>>
> 
> I see - the tiff is an output from scribus?

As written: Only indirect. Scribus can not save a file as tiff, but I 
used png and then (with Gimp) made a tiff file out of it.

> You can see what applications do when they are not capable of 
> transparency conversion? :-)

How? The image is totally flattende and looks quite as it should be, 
quite the way I made it in Scribus. All my problems would be solved if 
this file could be made cmyk and still be printed the way this file 
looks on the screen. No transparency in this file at all, no layers no 
nothing, just plain png -- made tiff by Gimp. I will try Imagemagick, 
perhaps that will be a help.

> Something strange happend here also, or did you change the colors of 
> some of your typo to hmm.. blue instead of light yellow?

ehm, no, actually blue is also there :-)

>>>> 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 :-/
> 
> No the file is not ok, sorry.

:-( Thanks for testing, though.

> For this time and if you are in a hurry, you might send me a pdf (pdf 
> X-3) with your rgb
> pictures and transparencies and embedded fonts in it and I will try to 
> convert it to something
> more usable , though I am not sure that the results will suffice.
> 
>>> 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?
> 
> With CM on you can turn on gammut warning in scribus (with scribus 
> 1.3.3.7 on OS X 10.3
> it seems broken, but I am still not really sure if I understand how it 
> is intended to work)

I have no idea how to do this in Linux and do not have the time to learn 
this now, so if everything else fail I will have to remake the 
background in Gimp, for now this would be easier ...

> With gammut warning on you should be able to see wich colors will be 
> clipped.
> 
> All "clean" rgb colors are not reproducable in cmyk or at least not 
> printable.
> 
> Above a sample of "generic" 2 dimensional color (omitting luminance) 
> spaces belonging to 1. cmyk and 2. rgb
> If you convert rgb to cmyk these spaces got to be mapped.
> Jon