[Scribus] The colors from the print are not expected.

Adolfo José Sáez Folgado adosafol
Tue Dec 11 13:52:13 CET 2007

I agree that there is a very good explanation for the color.
Also in the annotation to printer and print shop.
But ...
I do not use plates for the CMYK color, I use laser printers and
inquiring about the specifications in the PDF for export catalog and
whether it should take into account something else so that the color
is the most real.
In my laser print the color

2007/12/5, Craig Ringer <craig at postnewspapers.com.au>:
> > Adolfo Jos? S?ez Folgado wrote:
> >
> >> I must bear in mind that different inks and papers give different
> >> results, but how and when?
> >
> > "it varies". It's rather hard to predict.
> Just to clarify, in the following I meant "print shop" where I said
> "printer". It's common usage but can easily get confusing. I had someone
> point out (correctly) that it's particularly confusing here, so I
> thought I'd clarify just in case it's useful.
> I've applied clarifications in [ brackets ] below, for that issue and
> others.
> > The only way you'll find out for sure is to arrange "real" dummy proofs
> > with your [print shop], where they actually make the plates, run up the
> > press, etc. This is, unsurprisingly, expensive, though not as costly as
> > having to re-print the entire run. It is really the only way, even now,
> > to be truly sure that your job will have the colour you wanted it to.
> >
> > If you can't get dummies, find out if your [print shop] offers any sort of
> > soft-proofing. Some [print shop] can do quite reasonable simulations off
> > high end laser [print shop], where they run the job through the same RIP
> > they run the press off. Others might offer on-screen proofing in an
> > environment with controlled lighting and a very high end monitor. As far
> > as I know neither of these options can do a complete job of accounting
> > for different inks, media, etc, unless the press has been measured with
> > that particular combination. If the press has been measured with the
> > media you'll be using, etc, then the results should be very similar to
> > what'll print, and with a good soft proofing setup should be pretty
> > trustworthy.
>  >
> > If your [print shop] can't offer any sort of soft proof for you, you can try
> > doing some yourself. You must have a good ICC profile for your press or
> > you are wasting your time with this. Even with a good press profile I
> > would not rely on the results personally. This is rarely as easy as
> > setting a proof mode on a [laser/inkjet] printer. Maybe there are
>  > [laser/inkjet] printers out there
> > that do a decent job of simulating a press out of the box - but I've not
> > seen one yet. Someone PLEASE yell at me if they've had more success,
> > since I'd love to be shown to be wrong. Anyway, as far as I know to get
> > results you can rely on you'd probably have to do some proper
> > calibration on your [laser/inkjet] printer - requiring somewhat
>  > expensive hardware to
> > measure its output.* Assuming you *do* have an accurate profile for your
> > [laser/inkjet] printer and for your press it's possible to simulate the
>  > behaviour of the press on the [laser/inkjet] printer (with some
>  > limitations if the [laser/inkjet] printer's gamut
> > is more limited than the press's). The `tifficc' utility can actually do
> > this to an extent, and there are lots of commercial soft proofing
> > software options too.
> >
> > Of course, if your press profile is good, your display profile is good,
> > and your software is doing its job, in theory your on screen results
> > should look similar to what'll print anyway. This will only be true if
> > your software is set up for colour management and you have told it to
> > simulate the printer on the screen.
> >
> > Since right now it seems that you are not actually using a profile that
> > is specific to your press, that is probably the first thing you should
> > fix. Get an ICC profile from your [print shop] that describes their
> > particular press (and preferably media). They might tell you that their
> > RIP expects Euroscale Coated (or uncoated, if you're printing uncoated)
> > input, in which case you're OK with a generic profile since their RIP
> > will compensate. You really do need to check that, though, since some
> > [print shops] expect you to use a generic profile and compensate, others want
> > you to use their profile, and others again just won't know what you're
> > on about with all this "icc colour" stuff.
> >
> >> I can not accept with a red selenium lamp leaves printed in the
> >> catalog as dark orange
> >
> > If I'm not mistaken, you will have used a very intense, saturated red.
> > What kind of press are you going to be printing on? Many print
> > configurations won't handle some really intense reds and some other
> > colours. The use of such colours is called using "out-of-gamut" colours
> > - colours that the press cannot reproduce. Since your screen can
> > probably handle them just fine, they look OK on screen but won't print
> > properly.
> >
> > The problem you describe would be consistent with colour clipping /
> > shifting caused by the use of an out-of-gamut colour.
> >
> > Have you used the "press simulation" mode with gamut warning enabled to
> > check if the colour management engine thinks the problem colours are
>  > out-of-gamut for your press? It's possible to check for such problem
>  > colours (within limits) and warn about them. If you're NOT using press
> > simulation mode then you can use colours on screen that your press won't
>  > be able to handle and you won't have any idea you've done it.
> >
> > Scribus can do on-screen press simulation and gamut warning. See the
> > colour management preferences. Photoshop can also do it for particular
> > images, which is useful when you're working on adjusting an image to
> > print better. I think Krita 2 (coming in KDE 4) will do this too - hooray!
> >
> > If the colour is out of gamut for your press, you have a couple of options:
> >
> > - Make the whole image paler / duller / less saturated to bring the
>  > out-of-gamut colours back into the press's gamut. Playing around
> > with the  image in Photoshop  while press simulation and gamut
>  > warning mode is on is quite handy if you're trying to do this.
> > This is probably your best option, and it's the only one I know of
>  > that won't cost you a bunch of extra money
> > (except ignoring the problem). At the newspaper I work for we either
> > tweak the image to print OK or we find a more suitable image.
> >
> > - Spend more on a more expensive print run with better stock, fancier
> > presses, etc that can handle the difficult colour. For example, if
> > you're using cheap uncoated printing with coarse stock, you might find
> > that a coated press with better stock gets you an improved gamut that
> > can handle the difficult colour. But is it worth the extra cost?
>  >
> > - If you're trying to match a very specific colour sometimes your
> > printer can add it as an extra ink, you might print with (eg) CMYK + Red
> > . This is called spot colour printing. It won't help you if you're
> > trying to improve colour in photos etc, and is mostly useful for logos.
> >
> > - There are very special print processes that use more than four colours
> > for all colours - like HexaChrome for example. They're generally really
> > rather expensive but I mention them for completeness. If you used a
> > printer that used one of these processes you'd probably send them tagged
> > RGB PDF, not CMYK.
> >
> >> or a single PDF file that is so different from
> >> one machine to another, whether it is also not the fault of my work or
> >> the printer.
> >
> > A pdf almost always obviously appear differently on different computers
> > with different screens, OS versions, etc. This is because different
> > screens, video cards, etc display the "same" colour totally differently.
> > The computer cannot see the colour on the screen so it has no way to
> > compensate.
> >
> > The only time there should be any exception to this is when the computer
> > you are viewing the PDF on has a properly calibrated display and you've
> > enabled colour management in Acrobat. To calibrate a display you really
> > must have a hardware calibration device. By eye calibration really
> > doesn't do the job. If you have two computers with properly calibrated
> > displays the same PDF should look very similar when viewed on both, so
> > long as the colour settings in Acrobat are the same.
> >
> > If you're trying to use Acrobat to preview the PDF, make sure to tell
> > Acrobat to use the ICC profile for your press as its CMYK profile.
> > Otherwise you'll be getting wrong results since Acrobat will be assuming
> > untagged CMYK means something other than you intended.
> >
> > Complicated, isn't it?
> >
> > --
> > Craig Ringer
> >
> >
> > *  You might get away with a good scanner and a quality IT8 reference to
> > calibrate the scanner then build your printer profile from that, but (a)
> > there are issues where the printer & scanner gamuts don't overlap, and
> > (b) it's less accurate.
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