[Scribus] some qs about exporting pdfs

[Craig Ringer]

Bosse wrote:
> I have a scribus document and it will be exported as a PDF and send to a
> printing company (they actually prefer pdfs). They also have their own icc
> profiles which I use in Scribus.

Wow. There had to be one of them.

As a side note, today I did some testing on my work's print shop's ICC 
profiles, and found that the profiles supplied by the company my work 
used to use are actually a better match for the new current print shop's 
press than the ones that print shop supplies. Sad, really. When I 
configure Acrobat to treat untagged CMYK data as being in the new print 
shop's colour space, then preview the PDFs (untagged CMYK data) in 
Acrobat, everything looks good and looks how it was designed. Totally 
unlike how it prints. If I then set Acrobat to treat untagged CMYK as 
being in the old print shop's colour space and preview the PDFs, the 
on-screen appearance closely matches how it actually prints.

In other words, the print shop's supplied colour profile is so bad that 
the results from their press are vastly better simulated by the ICC 
profile of a another printing company.

My point? Just because the print shop has a profile, doesn't mean it's 
any good. Print shops sometimes supply generic profiles from the press 
manufacturer or even just a renamed SWOP or Euroscale profile. After 
all, proper press calibration requires expensive gear and some knowledge 
about colour (or the money to pay someone who has it). Sending the user 
a generic profile is OK (but not ideal due to gamut issues) if your RIP 
does a CMYK->CMYK conversion to the press's real colour space ... but my 
work's printer won't be the only one who doesn't do so.

If you're beginning to think you can't win and should just go back to 
demanding dummies from the print shop before approving any work, you're 
probably not wrong. One day maybe most print shops (rather than just the 
_good_ ones) will have a good enough grasp of ICC colour to get it 
right, but knowing the usual rate of progress I give it ten years plus.

> I want to get it as right as possible from the beginning and my question is: 
> 
> How reliable is print preview and the document I see in Acrobate reader when
> it comes to colour accuracy?

What OS are you using?

On Mac OS X and on Windows, if you have profiled your monitor & loaded 
that profile into the OS, it should provide a pretty accurate preview 
for PDFs that contain embedded colour profile information. If the PDF 
doesn't contain colour profiles it can still do a good job, you just 
need to have the profiles used in the PDF and to do a little more setup. 
You have to set Acrobat / Acrobat Reader's colour preferences up so that 
the CMYK and RGB working spaces match those you have used in your PDF. 
For example, if Scribus is set up to use SWOP Uncoated as the CMYK 
working space (which you do not override during PDF export) and you want 
to preview a PDF from Scribus then Adobe Reader should be set to use 
SWOP Uncoated for the working space too.

On Linux, Adobe Reader offers limited or no colour management. It is 
unlikely to provide reliable previews. I've never been happy with the 
results under Linux for PDFs that use anything but the RGB monitor 
colour space .

> I tried all the PDF standards (I don't know yet
> if they accept all of them) and they all look really good on screen and so
> does the printing preview.

Ask your printer what they want.

If they have supplied a colour profile, they probably want pre-converted 
CMYK colour, in which case the usual "Printer" export target in Scribus 
should be fine so long as your CMYK working space is set to their colour 
profile. Ask them to make sure.

Most printers want PDF 1.3 or PDF 1.4 . Your printer can tell you which, 
so ask them instead of guessing.  If they want PDF 1.3 then, due to 
scribus's lack of a transparency flattener, you will have to avoid using 
transparency in your design or use one of several somewhat cumbersome 
workarounds. If they will accept PDF 1.4, that's much nicer.

Few printers accept PDF/X-3 , the only other significant option. As 
Scribus currently handles it, PDF/X-3 quite often (always?) contains 
tagged RGB data. If your images are tagged with correct profiles or are 
in the same space as the working space set up in Scribus, the print 
shop's RIP should be able to convert the PDF to CMYK (or whatever they 
need) as well as or better than you can. Many print shops, however, do 
not accept PDF/X-3, either because their RIPs cannot handle it or 
because they do not know they can. They'll often reject it just because 
it contains RGB data (even though tagged RGB is *perfectly* *fine* for 
print).

> I also wonder about the ?solid colours? option under ?color management?. The
> icc profile from the printing company is not available there, is this how it
> should be?

I'm really not sure about that. I've never been clear on why Scribus 
separate this from the normal working spaces.

> I am also not sure what to do with ?solid colours? when exporting pdfs
> (colour tab).
> 
>  I assume  ?Colour? -->  ?Images:? --> ?Use ICC Profile?,  means that
> Scribus uses the profile I chose in CMYK pictures. Is that correct?

If I recall correctly that option name is very badly misleading. I 
cannot remember exactly what it actually does, only that I was very 
surprised by the results. The tooltips might explain in more detail, so 
try moving your mouse over the option and waiting a few seconds.

(I can't check now since the machine I'm at doesn't have Scribus and 
can't have it quickly & easily added).

> That 
> profile is also embedded in the image from the beginning. If not what is the
> difference here between an image and a picture? 

In general the two words can be treated as equivalent when dealing with 
computer software.

--
Craig Ringer